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  • Other Sources  (5,923)
  • NASA Technical Reports  (5,914)
  • Bibliography on Seismology  (9)
  • Earth Resources and Remote Sensing  (2,254)
  • METEOROLOGY AND CLIMATOLOGY  (1,902)
  • Instrumentation and Photography  (1,758)
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  • Other Sources  (5,923)
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  • NASA Technical Reports  (5,914)
  • Bibliography on Seismology  (9)
Keywords
Years
Year
  • 1
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    Starch columns: Analog model for basalt columns (1998)
    In:  J. Geophys. Res., Warszawa, American Geophysical Union, vol. 103, no. B7, pp. 15,239-15,253, pp. L08304, (ISSN: 1340-4202)
    Details
    Publication Date: 1998
    Keywords: Stress ; Rock mechanics ; Fracture ; Physical properties of rocks ; Laboratory measurements ; 5104 ; Fracture ; and ; flow ; 8010 ; Structural ; geology ; Fractures ; and ; faults ; 8168 ; Tectonophysics ; Stresses--general ; 8439 ; Volcanology ; Physics ; and ; chemistry ; of ; magma ; bodies ; Muller ; JGR
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  • 2
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    Dike propagation through an elastic plate (1998)
    In:  J. Geophys. Res., Kalamazoo, Michigan 49001, The Upjohn Company, vol. 103, no. B8, pp. 18,295-18,324, pp. L09603, (ISSN: 1340-4202)
    Details
    Publication Date: 1998
    Keywords: Elasticity ; Volcanology ; 8434 ; Volcanology ; Magma ; migration ; 8145 ; Tectonophysics ; JGR ; Physics ; of ; magma ; and ; magma ; bodies ; 8414 ; Eruption ; mechanisms
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  • 3
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    Focusing of magma in the upper mantle through dike interaction (2002)
    In:  J. Geophys. Res., Amsterdam, Schweizerbart'sche Verlagsbuchhandlung, vol. 107, no. B10, pp. ECV 6-1-ECV 6-17, pp. 2223, (ISSN 0016-8548, ISBN 3-510-50045-8)
    Details
    Publication Date: 2002
    Description: We use laboratory experiments and numerical models to quantify the effects of dike interaction on the focusing of magma as it ascends in the upper mantle. Laboratory experiments involve injecting buoyant fluid into the base of a tank filled with solidified gelatin. When we initiate two dikes parallel to each other, but separated by a horizontal distance x, they tend to merge as they ascend. This behavior is also predicted by numerical models of two-dimensional dikes. The key parameters that control the maximum horizontal separation x c over which dikes will intersect are dike driving pressures, dike head lengths L (i.e., the length over which driving pressure is large), and the difference between the principal stresses of the remote stress field. When the remote differential stress is small compared to the dike driving pressure, two dikes of equal driving pressure and length will intersect over distances of x c ? L. This distance decreases with increasing remote differential stress. We quantify the effects on magma transport from a broad lateral distribution of magma using numerical simulations of multiple-dike interaction. When the average dike spacing prior to interaction is within ?3 L and remote differential stresses are insignificant, dike interaction can focus magma over horizontal distances many times L but at least ?6 L. Dike interaction can focus magma in the asthenosphere beneath mid-ocean ridges for low mantle viscosities (?10 19 Pa s) and if dikes initiate with average separations of a few hundred meters, or less. Such focusing is predicted to grow dikes of increasing magma flux approaching lateral separations of a kilometer.
    Keywords: Fluids ; Plate tectonics ; ascent ; sheeted ; dykes ; Modelling ; JGR ; 8434 ; Volcanology: ; Magma ; migration ; 8145 ; Tectonophysics: ; Physics ; of ; magma ; and ; magma ; bodies ; 8120 ; Dynamics ; of ; lithosphere ; and ; mantle--general ; 3035 ; Marine ; Geology ; and ; Geophysics: ; Midocean ; ridge ; processes
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  • 4
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    Volcanic gas concentration and aquifer permeability estimated from tidal fluctuations in groundwater level: Case of Koshimizu Well in Izu-Oshima, Japan (1998)
    In:  Geophys. Res. Lett., New York, Conseil de l'Europe, vol. 25, no. 12, pp. 2237-2240, pp. B06307, (ISSN: 1340-4202)
    Details
    Publication Date: 1998
    Keywords: Volcanology ; Earthquake precursor: chemical (Rn, water(-level,...) ; TIDES ; Earth tides ; Physical properties of rocks ; 8135 ; Tectonophysics ; GRL ; Hydrothermal ; systems ; (8424) ; 8439 ; Volcanology ; Physics ; and ; chemistry ; of ; magma ; bodies ; 7223 ; Seismology ; Seismic ; hazard ; assessment ; and ; prediction ; 1832 ; Hydrology ; Groundwater ; transport
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  • 5
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    An accurate and efficient method for including the effects of topography in three-dimensional elastic models of ground deformation with applications to radar interferometry (2000)
    In:  J. Geophys. Res., Hannover, Dt. Geophys. Ges. e. V., vol. 105, no. B4, pp. 8103-8120, pp. 1058, (ISSN: 1340-4202)
    Details
    Publication Date: 2000
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; InSAR ; Geodesy ; Modelling ; JGR ; 1243 ; Geodesy ; and ; gravity ; Space ; geodetic ; surveys ; 3210 ; Mathematical ; geophysics ; (new ; field) ; Modeling ; 8145 ; Tectonophysics ; Physics ; of ; magma ; and ; magma ; bodies ; 8499 ; Volcanology
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  • 6
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    In situ ground deformation measurements from the summit of Axial Volcano during the 1998 volcanic episode (1999)
    In:  Geophys. Res. Lett., Kobe, 1, vol. 26, no. 23, pp. 3437-3440, pp. 8010, (ISBN: 0534351875, 2nd edition)
    Details
    Publication Date: 1999
    Description: The formation of ocean crust along the midocean ridge system is volumetrically one of the most important geological processes on the surface of the earth. Volcanic eruptions along the ridge can be catastrophic events during which magma rises to the surface of the sea floor to release heat and gases into turbulent megaplumes that disrupt the overlying water column, initiate and rejuvenate hydrothermal circulation, and trigger an outpouring of microbial debris. Though these events may persist only a few weeks or months at one site, taken together, they may play a major role in the oceanic biogeochemical cycle. Axial Volcano on the Juan de Fuca Ridge has become a laboratory for the study of ephemeral aspects of sea floor volcanism, including results from expeditionary, rapid response, and permanent instrument installations. The geological context and description of the most significant magmatic event on the Juan de Fuca Ridge in the past decade is provided by Embley et al. [3425]. Dziak and Fox [3429], describe a rapid increase in the seismicity remotely monitored by the U.S. Navy hydrophone array. The increase in seismic swarms is the earliest indicator that an eruption has begun. Within hours, volcanic deflation is observed in concert with increases in the bottom water temperature due to venting. Instruments in place for the first time during such a midocean ridge volcanic event measured ground deformation and caldera subsidence resulting from the extraction of magma as described by Fox [3437] and Chadwick et al. [3441], while a coincident outpouring of hot water recorded on moored temperature sensors is described in Baker et al. [3445]. A rapid response cruise in February brought researchers to the site only 14 days after the eruption began and in the midst of winter storms. Sohn et al. [3433] describe local seismicity derived from a network of sea floor hydrophones deployed during the February cruise. Repeated measurements of helium anomalies in the water column before and after the eruption are used by Lupton et al. [3449] to fingerprint the hydrothermal plume associated with the eruption, extending a considerable distance off-axis. Water samples collected during the February 1998 cruise were analyzed for hydrothermal methane and hydrogen by McLaughlin-West et al. [3453]. They find both species to be significantly elevated near the vents and invoke microbial processes to explain the observations.
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Volcanology ; 3035 ; Marine ; geology ; and ; geophysics ; Midocean ; ridge ; processes ; 8145 ; Tectonophysics ; Physics ; of ; magma ; and ; magma ; bodies ; 8419 ; Volcanology ; Eruption ; monitoring ; (7280) ; 8434 ; Magma ; migration ; GRL
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  • 7
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    Stress fields generating ring faults in volcanoes (1997)
    In:  Geophys. Res. Lett., London, Pergamon, vol. 24, no. 13, pp. 1559-1562, pp. B05401, (ISBN: 0534351875, 2nd edition)
    Details
    Publication Date: 1997
    Keywords: Volcanology ; Stress ; Iceland ; 8145 ; Tectonophysics ; Physics ; of ; magma ; and ; magma ; bodies ; 8414 ; Volcanology ; Eruption ; mechanisms ; GRL
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  • 8
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    Readjustment of the Krafla spreading segment to crustal rifting measured by satellite radar interferometry (1997)
    In:  Geophys. Res. Lett., Dordrecht, National Academy of Sciences of the USA, vol. 24, no. 15, pp. 1843-1846, pp. TC5003, (ISSN: 1340-4202)
    Details
    Publication Date: 1997
    Keywords: Iceland ; SAR ; InSAR ; Plate tectonics ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; 1209 ; Geodesy ; Gravimetry, Gravitation ; 8145 ; Tectonophysics ; Physics ; of ; magma ; and ; magma ; bodies ; 8150 ; Plate ; boundary ; general ; Massonet ; (3040) ; 3035 ; Marine ; geology ; and ; geophysics ; Midocean ; ridge ; processes ; Volcanology ; GRL
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  • 9
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    The effects of topography on magma chamber deformation models: Application to Mt. Etna and radar interferometry (1998)
    In:  Geophys. Res. Lett., Hannover, Dt. Geophys. Ges. e. V., vol. 25, no. 10, pp. 1549-1552, pp. 1058, (ISSN: 1340-4202)
    Details
    Publication Date: 1998
    Keywords: Volcanology ; Modelling ; InSAR ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; 1243 ; Geodesy ; and ; gravity ; Space ; geodetic ; surveys ; 3210 ; Mathematical ; geophysics ; (new ; field) ; Modeling ; 8145 ; Tectonophysics ; Physics ; of ; magma ; and ; magma ; bodies ; 8499 ; Volcanology ; General ; or ; miscellaneous ; GRL
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  • 10
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    Holographic Gratings for Optical Processing (2002)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: Investigation of astronomical objects and tracking of man-made space objects lead to generation of huge amount of information for optical processing. Traditional big-size optical elements (such as optical telescopes) have a tendency for increasing aperture size in order to improve sensitivity. This tendency leads to increasing of weight and costs of optical systems and stimulate search for the new, more adequate technologies. One approach to meet these demands is based on developing of holographic optical elements using new polymeric materials. We have investigated possibility to use new material PQ-PMMA (phenantrenequinone-doped PMMA (Polymethyl Methacrylate)) for fabrication of highly selective optical filters and fast spatial-temporal light modulators. This material was originally developed in Russia and later was tested in CalTech as a candidate material for optical storage. Our theoretical investigation predicts the possibility of realization of fast spatial and temporal light modulation, using volume reflection-type spectral filter. We have developed also model of holographic-grating recording in PQ-PMMA material, based on diffusional amplification. This mechanism of recording allow to receive high diffraction efficiency during recording of reflection-type volume holographic grating (holographic mirror). We also investigated recording of dynamic gratings in the photorefractive crystals LiNbO3 (LN) for space-based spectroscopy and for adaptive correction of aberrations in the telescope's mirrors. We have shown, that specific 'photogalvanic' mechanism of holographic grating recording in LN allow to realize recording of blazed gratings for volume and surface gratings. Possible applications of dynamic gratings in LN for amplification of images, transmitted through an imaging fiber guide was also demonstrated.
    Keywords: Instrumentation and Photography
    Type: Research Reports: 2001 NASA/ASEE Summer Faculty Fellowship Program; XXVII-1 - XXVII-9; NASA/CR-2002-211840
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  • 11
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    Hyperspectral Image Classification using a Self-Organizing Map (2001)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The use of hyperspectral data to determine the abundance of constituents in a certain portion of the Earth's surface relies on the capability of imaging spectrometers to provide a large amount of information at each pixel of a certain scene. Today, hyperspectral imaging sensors are capable of generating unprecedented volumes of radiometric data. The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), for example, routinely produces image cubes with 224 spectral bands. This undoubtedly opens a wide range of new possibilities, but the analysis of such a massive amount of information is not an easy task. In fact, most of the existing algorithms devoted to analyzing multispectral images are not applicable in the hyperspectral domain, because of the size and high dimensionality of the images. The application of neural networks to perform unsupervised classification of hyperspectral data has been tested by several authors and also by us in some previous work. We have also focused on analyzing the intrinsic capability of neural networks to parallelize the whole hyperspectral unmixing process. The results shown in this work indicate that neural network models are able to find clusters of closely related hyperspectral signatures, and thus can be used as a powerful tool to achieve the desired classification. The present work discusses the possibility of using a Self Organizing neural network to perform unsupervised classification of hyperspectral images. In sections 3 and 4, the topology of the proposed neural network and the training algorithm are respectively described. Section 5 provides the results we have obtained after applying the proposed methodology to real hyperspectral data, described in section 2. Different parameters in the learning stage have been modified in order to obtain a detailed description of their influence on the final results. Finally, in section 6 we provide the conclusions at which we have arrived.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the Tenth JPL Airborne Earth Science Workshop; 267-274
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  • 12
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    Spatial/Spectral Identification of Endmembers from AVIRIS Data using Mathematical Morphology (2001)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: During the last several years, a number of airborne and satellite hyperspectral sensors have been developed or improved for remote sensing applications. Imaging spectrometry allows the detection of materials, objects and regions in a particular scene with a high degree of accuracy. Hyperspectral data typically consist of hundreds of thousands of spectra, so the analysis of this information is a key issue. Mathematical morphology theory is a widely used nonlinear technique for image analysis and pattern recognition. Although it is especially well suited to segment binary or grayscale images with irregular and complex shapes, its application in the classification/segmentation of multispectral or hyperspectral images has been quite rare. In this paper, we discuss a new completely automated methodology to find endmembers in the hyperspectral data cube using mathematical morphology. The extension of classic morphology to the hyperspectral domain allows us to integrate spectral and spatial information in the analysis process. In Section 3, some basic concepts about mathematical morphology and the technical details of our algorithm are provided. In Section 4, the accuracy of the proposed method is tested by its application to real hyperspectral data obtained from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imaging spectrometer. Some details about these data and reference results, obtained by well-known endmember extraction techniques, are provided in Section 2. Finally, in Section 5 we expose the main conclusions at which we have arrived.
    Keywords: Earth Resources and Remote Sensing
    Type: Proceedings of the Tenth JPL Airborne Earth Science Workshop; 309-319
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  • 13
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    Ultra-High Density Holographic Memory Module with Solid-State Architecture (2000)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: NASA's terrestrial. space, and deep-space missions require technology that allows storing. retrieving, and processing a large volume of information. Holographic memory offers high-density data storage with parallel access and high throughput. Several methods exist for data multiplexing based on the fundamental principles of volume hologram selectivity. We recently demonstrated that a spatial (amplitude-phase) encoding of the reference wave (SERW) looks promising as a way to increase the storage density. The SERW hologram offers a method other than traditional methods of selectivity, such as spatial de-correlation between recorded and reconstruction fields, In this report we present the experimental results of the SERW-hologram memory module with solid-state architecture, which is of particular interest for space operations.
    Keywords: Instrumentation and Photography
    Type: Non-Volatile Memory Technology Symposium 2000: Proceedings; 106-111; JPL-Publ-00-15
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  • 14
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    Calibration of of Sun Photometers and Sky Radiance Sensors (2001)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: The main source of error in retrieving aerosol optical thicknesses using sun photometry comes from the determination of the TOA voltages. The degradation of interference filters is the most important source of the long-term changes in the cross-calibrations. Although major improvements have been made in the design of the filters (interference filters fabricated using ion-assisted deposition), the filters remain the principal factor limiting performance of the sun photometers. Degradation of filters necessitates frequent calibration of sun photometers and frequent measurements of the filter transmission or the relative system response. The degradation of the filters mounted on the CIMEL sun photometers have been monitored since 1993 by the Aerosol Robotic Network (AERONET) project. The decay reported by Holben et al. for the first two years of a CIMEL#s operation is between 1 and 5%. Nevertheless, the filters mounted on CIMEL instruments are regularly replaced after two years of use. The cross-calibration technique consists of taking measurements concurrently with the uncalibrated and the reference sun photometers. While analyzing measurements, the quality of the calibration has to be checked, using the following considerations: (1) any cirrus clouds suspected to be masking the sun, during the calibration period, need to be reported and the corresponding data set removed; and (2) the stability of the day needs to be checked. This chapter will describe calibration techniques, facilities, and protocols used for calibrating sun photometers and sky radiometers.
    Keywords: Instrumentation and Photography
    Type: In Situ Aerosol Optical Thinkness Collected by the SIMBIOS Program (1997-2000): Protocols, and and Data QC and Analysis; 11-21; NASA/TM-2001-209982
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  • 15
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    Summary Report of the First International Symposium on Strain Gauge Balances and Workshop on AoA/Model Deformation Measurement Techniques (1998)
    In:  CASI
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    Publication Date: 2011-10-14
    Description: The first International Symposium on Strain Gauge Balances was sponsored under the auspices of the NASA Langley Research Center (LaRC), Hampton, Virginia. Held at the LaRC Reid Conference Center, the Symposium provided an open international forum for presentation, discussion, and exchange of technical information among wind tunnel test technique specialists and strain gauge balance designers. The Symposium also served to initiate organized professional activities among the participating and relevant international technical communities. The program included a panel discussion, technical paper sessions, tours of local facilities, and vendor exhibits. Over 130 delegates were in attendance from 15 countries. A steering committee was formed to plan a second international balance symposium tentatively scheduled to be hosted in the United Kingdom in 1998 or 1999. The Balance Symposium was followed bv the half-day, Workshop on Angle of Attack and Model Deformation on the afternoon of October 25. The thrust of the Workshop was to assess the state of the art in angle of attack (AoA) and model deformation measurement techniques and to discuss future developments.
    Keywords: Instrumentation and Photography
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  • 16
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    Rare-Earth Garnets and Perovskites for Space-Based ADR Cooling at High T and Low H (2001)
    In:  CASI
    Details
    Publication Date: 2011-09-13
    Description: Future NASA satellite detector systems must be cooled to the 0.1 K temperature range to meet the stringent energy resolution and sensitivity requirements demanded by mid-term astronomy missions. The development of adiabatic demagnetization refrigeration (ADR) materials that can efficiently cool from the passive radiative cooling limit of approx. 30 K down to sub-Kelvin under low magnetic fields (H less than or equal to 3 T) would represent a significant improvement in space-based cooling technology. Governed by these engineering goals, our efforts have focused on quantifying the change in magnetic entropy of rare-earth garnets and perovskites. Various compositions within the gadolinium gallium iron garnet solid solution series (GGIG, Gd3Ga(5-x)Fe(x)O12, 0.00 less than or equal to X less than or equal to 5.00) and gadolinium aluminum perovskite (GAP, GdAlO3) have been synthesized via an organometallic complex approach and confirmed with powder x-ray diffraction. The magnetization of the GGIG and GAP materials has been measured as a function of composition (0.00 less than or equal to X less than or equal to 5.00), temperature (2 K less than or equal to T less than or equal to 30 K) and applied magnetic field (0 T less than or equal to H less than or equal to 3 T). The magnetic entropy change (DeltaS(sub mag)) between 0 T and 3 T was determined from the magnetization data. In the GGIG system, DeltaS(sub mag) was compositionally dependent; Fe(sup 3+) additions up to X less than or equal to 2.44 increased DeltaS(sub mag) at T 〉 5 K. For GAP, DeltaS(sub mag) was similar to that of GGIG, X = 0.00, both in terms of magnitude and temperature dependence at T 〉 10 K. However, the DeltaS(sub mag) of GAP at T 〈 10 K was less than the endmember GGIG composition, X = 0.00, and exhibited maximum approx. 5 K.
    Keywords: Instrumentation and Photography
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  • 17
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    JPL VLBI Group Report for 1998-1999 (1999)
    In:  CASI
    Details
    Publication Date: 2011-09-13
    Description: This report describes the transitional activities of the JPL Analysis Center.
    Keywords: Earth Resources and Remote Sensing
    Type: International VLBI Service for Geodesy and Astrometry: 1999 Annual Report; 215-216; NASA/TP-1999-209243
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  • 18
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    Overcoats for the Improved Performance of PdCr High Temperature Thin Film Strain Gages (1998)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: Overcoat protection schemes for thin film devices have typically focused on inhibiting the growth of native oxides formed on the sensor surface, rather than on improving the passivating nature of these native oxides. Here, thin sputtered Cr overcoats and heat treatments in varying oxygen partial pressures enhanced the passivating nature of native Cr203 films formed on PdCr thin film strain gages. Results of strain tests using sensors protected using this approach are presented and the implications are discussed. PdCr gages with sputtered Cr overcoats withstood 12,000 dynamic strain cycles of 1100 micro-epsilon during 100 hours of testing at a temperature of 1000 C in air. Gage factors of 1.3 with drift rates as low as 0.1 Omega/hr were achieved for devices having a nominal resistance of approximately 100 Omega's. TCR's ranging from +550 ppm/C to +798 ppm/C were realized depending on the overcoat and thermal history. Possible mechanisms for an anomaly in the electrical characteristics of these films at 800 C and improvements in stability due to the use of overcoats are presented.
    Keywords: Instrumentation and Photography
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  • 19
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    Advanced Measurement Technology at NASA Langley Research Center (1998)
    In:  CASI
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    Publication Date: 2011-10-14
    Description: Instrumentation systems have always been essential components of world class wind tunnels and laboratories. Langley continues to be on the forefront of the development of advanced systems for aerospace applications. This paper will describe recent advances in selected measurement systems which have had significant impact on aerospace testing. To fully understand the aerodynamics and aerothermodynamics influencing aerospace vehicles, highly accurate and repeatable measurements need to be made of critical phenomena. However, to maintain leadership in a highly competitive world market, productivity enhancement and the development of new capabilities must also be addressed aggressively. The accomplishment of these sometimes conflicting requirements has been the challenge of advanced measurement developers. However, several new technologies have recently matured to the point where they have enabled the achievement of these goals. One of the critical areas where advanced measurement systems are required is flow field velocity measurements. These measurements are required to correctly characterize the flowfield under study, to quantify the aerodynamic performance of test articles and to assess the effect of aerodynamic vehicles on their environment. Advanced measurement systems are also making great strides in obtaining planar measurements of other important thermodynamic quantities, including species concentration, temperature, pressure and the speed of sound. Langley has been on the forefront of applying these technologies to practical wind tunnel environments. New capabilities in Projection Moire Interferometry and Acoustics Array Measurement systems have extended our capabilities into the model deformation, vibration and noise measurement arenas. An overview of the status of these techniques and recent applications in practical environments will be presented in this paper.
    Keywords: Instrumentation and Photography
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  • 20
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    TLD efficiency of 7LiF for doses deposited by high-LET particles (2000)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The efficiency of 7 LiF TLDs (TLD-700) in registering dose from high-LET (〉 or = 10 keV/micrometers) charged particles (relative to 137Cs gamma rays) has been measured for a number of accelerated heavy ions at various particle accelerator facilities. These measured efficiency values have been compared with similar results obtained from the open literature and a dose efficiency function has been fitted to the combined data set. While it was found that the dose efficiency is not only a function of LET, but also of the charge of the incident particle, the fitted function can be used to correct the undermeasured value of dose from exposures made in mixed radiation fields where LET information is available. This LET-dependent dose efficiency function is used in our laboratory in determining total absorbed dose and dose equivalent from combined TLD and CR-39 plastic nuclear track detector measurements.
    Keywords: Instrumentation and Photography
    Type: Radiation measurements (ISSN 1350-4487); Volume 32; 3; 211-4
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  • 21
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    Compact CH4 sensor based on difference frequency mixing of diode lasers in quasi-phasematched LiNbO3 (2000)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A compact, portable and robust room temperature CH4 sensor is reported. By difference frequency mixing a 500 mW alpha-DFB diode laser at 1066 nm and an erbium-doped fiber amplified 1574 nm DFB diode laser in periodically poled lithium niobate up to 7 (mu)W of narrowband radiation at 3.3 microns is generated. Real-time monitoring of CH4 over a 7 day period using direct absorption in an open-path multipass cell (L = 36 m) demonstrates a detection precision of +/- 14 ppb.
    Keywords: Instrumentation and Photography
    Type: Optics communications (ISSN 0030-4018); Volume 175; 4-6; 461-8
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  • 22
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    A satellite-based multichannel infrared radiometer to sound the atmosphere (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: This paper describes a 12-channel infrared radiometer with the acronym SABER (Sounding of the Atmosphere using Broadband Emission radiometry) that has been selected by NASA to fly on the TIMED (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics) mission.
    Keywords: Instrumentation and Photography
    Type: ; 130-132
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  • 23
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    Vertical transport by convective clouds: Comparisons of three modeling approaches (1995)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A preliminary comparison of the GEOS-1 (Goddard Earth Observing System) data assimilation system convective cloud mass fluxes with fluxes from a cloud-resolving model (the Goddard Cumulus Ensemble Model, GCE) is reported. A squall line case study (10-11 June 1985 Oklahoma PRESTORM episode) is the basis of the comparison. Regional (central U. S.) monthly total convective mass flux for June 1985 from GEOS-1 compares favorably with estimates from a statistical/dynamical approach using GCE simulations and satellite-derived cloud observations. The GEOS-1 convective mass fluxes produce reasonable estimates of monthly-averaged regional convective venting of CO from the boundary layer at least in an urban-influenced continental region, suggesting that they can be used in tracer transport simulations.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Geophysical Research Letters (ISSN 0094-8276); 22; 9; p. 1089-1092
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    Remote sensing of flooding in the U.S. upper Midwest during the summer of 1993 (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The U.S. upper Midwest was subjected to severe flooding during the summer of 1993. Heavy rainfall in the Mississippi River basin from April through July caused flooding on many Midwest rivers, including the Mississippi, Illinois, Missouri, and Kansas Rivers. The flood crest of 15.1 m at St. Louis, Missouri, on 1 August 1993 was the highest ever measured, surpassing the previous record of 13.2 m set on 28 April 1973. Damage estimates include at least 47 flood-related deaths and a total damage cost of $12 billion. Remotely sensed imagery of severe flooding in the U.S. Midwest was obtained under cloud-free skies on 29 July 1993 by the MODIS (Moderate Resolution Imaging Spectroradiometer) Airborne Simulator (MAS). The MAS is a newly developed scanning spectrometer with 50 spectral bands in the wavelength range 0.55-14.3 micrometers. Estimation of the total flooded area in the MAS scene acquired near St. Louis was accomplished by comparing the MAS scene to a Landsat-5 thematic mapper (TM) scene of the same area acquired on 14 April 1984 in nonflood conditions. For comparison, the MAS band centered at 0.94 micrometers and the TM band centered at 1.65 micrometers were selected because of the high contrast seen in these bands between land and water-covered surfaces. An estimate of the area covered by water in the MAS and TM scenes was obtained by developing land/water brightness thresholds from histograms of the MAS and TM digital image data. Afetr applying the thresholds, the difference between the area covered by water in the MAS and TM scenes, and hence the flooded area in the MAS scene, was found to be about 396 sq km, or about 153 square miles.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 76; 6; p. 933-943
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    First global WCRP shortwave surface radiation budget dataset (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Shortwave radiative fluxes that reach the earth's surface are key factors that influence atmospheric and oceanic circulations as well as surface climate. Yet, information on these fluxes is meager. Surface site data are generally available from only a limited number of observing stations over land. Much less is known about the large-scale variability of the shortwave radiative fluxes over the oceans, which cover most of the globe. Recognizing the need to produce global-scale fields of such fluxes for use in climate research, the World Climate Research Program has initiated activities that led to the establishment of the Surface Radiation Budget Climatology Project with the ultimate goal to determine various components of the surface radiation budget from satellite data. In this paper, the first global products that resulted from this activity are described. Monthly and daily data on a 280-km grid scale are available. Samples of climate parameters obtainable from the dataset are presented. Emphasis is given to validation and limitations of the results. For most of the globe, satellite estimates have bias values between +/- 20 W/sq m and root mean square (rms) values are around 25 W/sq m. There are specific regions with much larger uncertainties however.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 76; 6; p. 905-922
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    Lidar-measured winds from space: A key component for weather and climate prediction (1995)
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    Publication Date: 2011-08-24
    Description: The deployment of a space-based Doppler lidar would provide information that is fundamental to advancing the understanding and prediction of weather and climate. This paper reviews the concepts of wind measurement by Doppler lidar, highlights the results of some observing system simulation experiments with lidar winds, and discusses the important advances in earth system science anticipated with lidar winds. Observing system simulation experiments, conducted using two different general circulation models, have shown (1) that there is a significant improvement in the forecast accuracy over the Southern Hemisphere and tropical oceans resulting from the assimilation of simulated satellite wind data, and (2) that wind data are significantly more effective than temperature or moisture data in controlling analysis error. Because accurate wind observations are currently almost entirely unavailable for the vast majority of tropical cyclones worldwide, lidar winds have the potential to substan- tially improve tropical cyclone forecasts. Similarly, to improve water vapor flux divergence calculations, a direct measure of the ageostrophic wind is needed since the present level of uncer- tainty cannot be reduced with better temperature and moisture soundings alone.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 76; 6; p. 869-888
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    Global precipitation estimates based on a technique for combining satellite-based estimates, rain gauge analysis, and NWP model precipitation information (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The 'satellite-gauge model' (SGM) technique is described for combining precipitation estimates from microwave satellite data, infrared satellite data, rain gauge analyses, and numerical weather prediction models into improved estimates of global precipitation. Throughout, monthly estimates on a 2.5 degrees x 2.5 degrees lat-long grid are employed. First, a multisatellite product is developed using a combination of low-orbit microwave and geosynchronous-orbit infrared data in the latitude range 40 degrees N - 40 degrees S (the adjusted geosynchronous precipitation index) and low-orbit microwave data alone at higher latitudes. Then the rain gauge analysis is brougth in, weighting each field by its inverse relative error variance to produce a nearly global, observationally based precipitation estimate. To produce a complete global estimate, the numerical model results are used to fill data voids in the combined satellite-gauge estimate. Our sequential approach to combining estimates allows a user to select the multisatellite estimate, the satellite-gauge estimate, or the full SGM estimate (observationally based estimates plus the model information). The primary limitation in the method is imperfections in the estimation of relative error for the individual fields. The SGM results for one year of data (July 1987 to June 1988) show important differences from the individual estimates, including model estimates as well as climatological estimates. In general, the SGM results are drier in the subtropics than the model and climatological results, reflecting the relatively dry microwave estimates that dominate the SGM in oceanic regions.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Climate (ISSN 0894-8755); 8; 5, pt; p. 1284-1295
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  • 28
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    Tropical stratospheric water vapor measured by the microwave limb sounder (MLS) (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The lower stratospheric variability of equatorial water vapor, measured by the Microwave Limb Sounder (MLS), follows an annual cycle modulated by the quasi-biennial oscillation. At levels higher in the stratosphere, water vapor measurements exhibit a semi-annual oscillatory signal with the largest amplitudes at 2.2 and 1hPa. Zonal-mean cross sections of MLS water vapor are consistent with previous satellite measurements from the limb infrared monitor of the stratosphere (LIMS) and the stratospheric Aerosol and Gas Experiment 2 (SAGE 2) instruments in that they show water vapor increasing upwards and the polewards from a well defined minimum in the tropics. The minimum values vary in height between the retrieved 46 and 22hPa pressure levels.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Geophysical Research Letters (ISSN 0094-8276); 22; 6; p. 691-694
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  • 29
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    New generation lidar systems for eye safe full time observations (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The traditional lidar over the last thirty years has typically been a big pulse low repetition rate system. Pulse energies are in the 0.1 to 1.0 J range and repetition rates from 0.1 to 10 Hz. While such systems have proven to be good research tools, they have a number of limitations that prevent them from moving beyond lidar research to operational, application oriented instruments. These problems include a lack of eye safety, very low efficiency, poor reliability, lack of ruggedness and high development and operating costs. Recent advances in solid state laser, detectors and data systems have enabled the development of a new generation of lidar technology that meets the need for routine, application oriented instruments. In this paper the new approaches to operational lidar systems will be discussed. Micro pulse lidar (MPL) systems are currently in use, and their technology is highlighted. The basis and current development of continuous wave (CW) lidar and potential of other technical approaches is presented.
    Keywords: Instrumentation and Photography
    Type: ; 26-28
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  • 30
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    The reaction O((3)P) + HOBr: Temperature dependence of the rate constant and importance of the reaction as an HOBr stratospheric loss process (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The absolute rate constant for the reaction O((3)P) + HOBr has been measured between T = 233K and 423K using the discharge-flow kinetic technique coupled to mass spectrometric detection. The value of the rate coefficient at room temperature is (2.5 +/- 0.6) x 10(exp -11)cu cm/molecule/s and the derived Arrhenius expression is (1.4 +/- 0.5) x 10(exp -10) exp((-430 +/- 260)/T)cu cm/molecule/s. From these rate data the atmospheric lifetime of HOBr with respect to reaction with O((3)P) is about 0.6h at z = 25 km which is comparable to the photolysis lifetime based on recent measurements of the UV cross section for HOBr. Implications for HOBr loss in the stratosphere have been tested using a 1D photochemical box model. With the inclusion of the rate parameters and products for the O + HOBr reaction, calculated concentration profiles of BrO increase by up to 33% around z = 35 km. This result indicates that the inclusion of the O + HOBr reaction in global atmospheric chemistry models may have an impact on bromine partitioning in the middle atmosphere.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Geophysical Research Letters (ISSN 0094-8276); 22; 7; p. 827-830
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    A diagnostic analysis of the VVP single-doppler retrieval technique (1995)
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    Publication Date: 2011-08-24
    Description: A diagnostic analysis of the VVP (volume velocity processing) retrieval method is presented, with emphasis on understanding the technique as a linear, multivariate regression. Similarities and differences to the velocity-azimuth display and extended velocity-azimuth display retrieval techniques are discussed, using this framework. Conventional regression diagnostics are then employed to quantitatively determine situations in which the VVP technique is likely to fail. An algorithm for preparation and analysis of a robust VVP retrieval is developed and applied to synthetic and actual datasets with high temporal and spatial resolution. A fundamental (but quantifiable) limitation to some forms of VVP analysis is inadequate sampling dispersion in the n space of the multivariate regression, manifest as a collinearity between the basis functions of some fitted parameters. Such collinearity may be present either in the definition of these basis functions or in their realization in a given sampling configuration. This nonorthogonality may cause numerical instability, variance inflation (decrease in robustness), and increased sensitivity to bias from neglected wind components. It is shown that these effects prevent the application of VVP to small azimuthal sectors of data. The behavior of the VVP regression is further diagnosed over a wide range of sampling constraints, and reasonable sector limits are established.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 12; 2; p. 230-248
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    An analysis of the Antarctic Halogen Occultation Experiment trace gas observations (1995)
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    Publication Date: 2011-08-24
    Description: Analysis of the version 16 Halogen Occultation Experiment (HALOE) CH4 data shows that this long-lived trace gas is well correlated with potential vorticity (PV) computed from National Meteorological Center balanced winds. Analyzing late September and October 1992 data, we show that very low CH4 values are confined to the interior of a vortex edge defined by the maximum gradient in PV. The CH4 and HF time tendency is used to estimate the descent rate in the Antarctic vortex. After removing a component of the trend correlated with the HALOE sampling pattern, we compute the lower stratosphere vertical descent rates and net heaing rates in the spring Antarctic vortex. Our computations of the spring Antarctic vortex heating rates give -0.5 to -0.1 K/day. Over the winter season, the overall lower stratospheric descent rate averages about 1.8-1.5 km/month. These computations are in line with radiative transfer estimates of the heating and descent rate. The HALOE data thus appear to be consistent with the picture of an isolated lower stratospheric Antarctic vortex.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 100; D3; p. 5159-5172
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    Partitioning of ocean and land uptake of CO2 as inferred by delta C-13 measurements from the NOAA Climate Monitoring and Diagnostics Laboratory Global Air Sampling Network (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Using delta C-13 measurements in atmospheric CO2 from a cooperative global air sampling network, we determined the partitioning of the net uptake of CO2 between ocean and land as a function of latitude and time. The majority of delta C-13 measurements were made at the Institute of Arctic and Alpine Research (INSTAAR) of the University of Colorado. We perform an inverse deconvolution of both CO2 and delta C-13 observations, using a two-dimensional model of atmospheric transport. Also, the discrimination against C-13 by plant photosynthesis, as a function of latitude and time, is calculated from global runs of the simple biosphere (SiB) model. Uncertainty due to the longitudinal structure of the data, which is not represented by the model, is studied through a bootstrap analysis by adding and omitting measurement sites. The resulting error estimates for our inferred sources and sinks are of the order of 1 GTC (1 GTC = 10(exp 15) gC). Such error bars do not reflect potential systematic errors arising from our estimates of the isotopic disequilibria between the atmosphere and the oceans and biosphere, which are estimated in a separate sensitivity analysis. With respect to global totals for 1992 we found that 3.2 GTC of carbon dissolved into the ocean and that 1.5 GTC were sequestered by land ecosystems. Northern hemisphere ocean gyres north of 15 deg N absorbed 2.7 GTC. The equatorial oceans between 10 deg S and 10 deg N were a net source to the atmosphere of 0.9 GTC. We obtained a sink of 1.6 GTC in southern ocean gyres south of 20 deg S, although the deconvolution is poorly constrained by sparse data coverage at high southern latitudes. The seasonal uptake of CO2 in the northern gyres appears to be correlated with a bloom of phytoplankton in surface waters. On land, northern temperate and boreal ecosystems between 35 deg N and 65 deg N were found to be a major sink of CO2 in 1992, as large as 3.5 GTC. Northern tropical ecosystems (equator-30 deg N) appear to be a net source to the source to the atmosphere of 2 GTC which could reflect biomass burning. A small sink, 0.3 GTC, was inferred for southern tropical ecosystems (30 deg S-equator).
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 100; D3; p. 5051-5070
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    Assessment of the global monthly mean surface insolation estimated from satellite measurements using global energy balance archive data (1995)
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    Publication Date: 2011-08-24
    Description: Global sets of surface radiation budget (SRB) have been obtained from satellite programs. These satellite-based estimates need validation with ground-truth observations. This study validates the estimates of monthly mean surface insolation contained in two satellite-based SRB datasets with the surface measurements made at worldwide radiation stations from the Global Energy Balance Archive (GEBA). One dataset was developed from the Earth Radiation Budget Experiment (ERBE) using the algorithm of Li et al. (ERBE/SRB), and the other from the International Satellite Cloud Climatology Project (ISCCP) using the algorithm of Pinker and Laszlo and that of Staylor (GEWEX/SRB). Since the ERBE/SRB data contain the surface net solar radiation only, the values of surface insolation were derived by making use of the surface albedo data contained GEWEX/SRB product. The resulting surface insolation has a bias error near zero and a root-mean-square error (RMSE) between 8 and 28 W/sq m. The RMSE is mainly associated with poor representation of surface observations within a grid cell. When the number of surface observations are sufficient, the random error is estimated to be about 5 W/sq m with present satellite-based estimates. In addition to demonstrating the strength of the retrieving method, the small random error demonstrates how well the ERBE derives from the monthly mean fluxes at the top of the atmosphere (TOA). A larger scatter is found for the comparison of transmissivity than for that of insolation. Month to month comparison of insolation reveals a weak seasonal trend in bias error with an amplitude of about 3 W/sq m. As for the insolation data from the GEWEX/SRB, larger bias errors of 5-10 W/sq m are evident with stronger seasonal trends and almost identical RMSEs.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Climate (ISSN 0894-8755); 8; 2; p.315-328
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    Workshop on Satellite and In situ Observations for Climate Prediction (1995)
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    Publication Date: 2011-08-24
    Description: Participants in this workshop, which convened in Venice, Italy, 6-8 May 1993, met to consider the current state of climate monitoring programs and instrumentation for the purpose of climatological prediction on short-term (seasonal to interannual) timescales. Data quality and coverage requirements for definition of oceanographic heat and momentum fluxes, scales of inter- and intra-annual variability, and land-ocean-atmosphere exchange processes were examined. Advantages and disadvantages of earth-based and spaceborne monitoring systems were considered, as were the structures for future monitoring networks, research programs, and modeling studies.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 76; 2; p. 241-249
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  • 36
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    Anomalous meridional thermospheric neutral winds in the AE-E NATE data: Effects of the equatorial nighttime pressure bulge (1995)
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    Publication Date: 2011-08-24
    Description: The work described here makes it possible to identify anomalous wind behavior such as the nighttime meridional wind abatements that occur at F-region heights. A new analysis technique uses a simple empirical wind model to simulate measurements of 'normal' winds (as measured by the Neutral Atmosphere and Temperature Experiment (NATE) that flew on the Atmosphere Explorer-E (AE-E)) to highlight anomalous wind measurements made by the satellite while in circular orbits at 270-290 km altitude. Our approach is based on the recognition that the 'in orbit' wind variation must show the combined effects of the diurnal wind variation as seen from the ground with the latitude variation of the satellite orbit. For the data period 77250-78035 examined thus far, the wind abatement always occurred with a corresponding pressure or temperature maximum, and was detected on 12 out of the 36 nights with data. This study has revealed that the wind abatement occur only during or shortly after increases in solar extreme ultraviolet (EUV) flux, as indicated by daily radio flux measurements. In the past, nighttime wind reversals at mid-latitudes have been associated with increased geomagnetic activity. This study indicates that intensified solar EUV heating may be responsible for anomalous thermospheric nighttime winds at mid-latitudes.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Geopysical Research Letters (ISSN 0094-8276); 22; 3; p. 271-274
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    Classification of rain regimes by the three-dimensional properties of reflectivity fields (1995)
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    Publication Date: 2011-08-24
    Description: An automated scheme to characterize precipitation echoes within small windows in the radar field is presented and applied to previously subjectively classified tropical rain cloud systems near Darwin, Australia. The classification parameters are (a) E(sub e), effective efficiency, as determined by cloud-top and cloud-base water vapor saturation mixing ratios; (b) BBF, brightband fraction, as determined by the fraction of the radar echo area in which the maximal reflectivity occurs within +/- 1.5 km of the 0 C isotherm level; and (c) del(sub r) Z, radial reflectivity gradients (dB/km). These classification criteria were applied to tropical rain cloud systems near Darwin, Australia, and to winter convective rain cloud systems in Israel. Both sets of measurements were made with nearly identical networks of C-band radars and rain gauge networks. The results of the application of these objective classification criteria to several independently predetermined rain regimes in Darwin have shown that better organized rain systems have smaller del(sub r) Z and larger BBF. Similarly, smaller del(sub r)Z and larger BBF were also observed from maritime rain cloud systems, as compared to continental rain cloud systems with the same degree of organization. Continental rain cloud system, regardless of their degree of organization, have larger depths, as expressed by E(sub e). The rainfall analyses presented in this study are based exclusively on rain gauge measurements, while radar information was used only to classify the individual gauge measurements.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 34; 1; p. 198-211
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    Near-infrared diode laser based spectroscopic detection of ammonia: a comparative study of photoacoustic and direct optical absorption methods (2002)
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    Publication Date: 2011-08-24
    Description: A photoacoustic spectroscopic (PAS) and a direct optical absorption spectroscopic (OAS) gas sensor, both using continuous-wave room-temperature diode lasers operating at 1531.8 nm, were compared on the basis of ammonia detection. Excellent linear correlation between the detector signals of the two systems was found. Although the physical properties and the mode of operation of both sensors were significantly different, their performances were found to be remarkably similar, with a sub-ppm level minimum detectable concentration of ammonia and a fast response time in the range of a few minutes.
    Keywords: Instrumentation and Photography
    Type: Applied spectroscopy (ISSN 0003-7028); Volume 56; 6; 715-9
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  • 39
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    A quasi-static method for determining the characteristics of a motion capture camera system in a "split-volume" configuration (2002)
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    Publication Date: 2011-08-24
    Description: The purpose of this study was to determine the accuracy, repeatability and resolution of a six-camera Motion Analysis system in a vertical split-volume configuration using a unique quasi-static methodology. The position of a reflective marker was recorded while it was moved quasi-statically over a range of 2.54 mm (0.100 inches) via a linearly-translating table. The table was placed at five different heights to cover both sub-volumes and the overlapping region. Data analysis showed that accuracy, repeatability and resolution values were consistent across all regions of the split-volume, including the overlapping section.
    Keywords: Instrumentation and Photography
    Type: Gait & posture (ISSN 0966-6362); Volume 16; 3; 283-7
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    Marine ecosystem appropriation in the Indo-Pacific: a case study of the live reef fish food trade (2003)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Our ecological footprint analyses of coral reef fish fisheries and, in particular, the live reef fish food trade (FT), indicate many countries' current consumption exceeds estimated sustainable per capita global, regional and local coral reef production levels. Hong Kong appropriates 25% of SE Asia's annual reef fish production of 135 260-286 560 tonnes (t) through its FT demand, exceeding regional biocapacity by 8.3 times; reef fish fisheries demand out-paces sustainable production in the Indo-Pacific and SE Asia by 2.5 and 6 times. In contrast, most Pacific islands live within their own reef fisheries means with local demand at 〈 20% of total capacity in Oceania. The FT annually requisitions up to 40% of SE Asia's estimated reef fish and virtually all of its estimated grouper yields. Our results underscore the unsustainable nature of the FT and the urgent need for regional management and conservation of coral reef fisheries in the Indo-Pacific.
    Keywords: Earth Resources and Remote Sensing
    Type: Ambio (ISSN 0044-7447); Volume 32; 7; 481-8
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    Effect of stratospheric aerosol on ozone profile from BUV measurements (1995)
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    Publication Date: 2011-08-24
    Description: Results of a simulation study on the effects of optically thick stratospheric sulfate aerosol layers on the backscattered ultraviolet radiation (buv) in the range 256-340 nm are presented. In general, the increased Mie scattering produced by the aerosols results in an enhancement of the buv radiation. The increase is approximately linear with optical depth and strongly depends on solar zenith angle and aerosol layer altitude in relation to the ozone maximum. The effect is greatest at those wavelenghts whose contribution functions peak in the vicinity of the densest part of the aerosol layer. The aerosol induced perturbation of the buv field affects the ozone profile retrieval from space measurements by the Solar Backscatter Ultraviolet Experiment (SBUV) experiment. In the tropical stratosphere, the retrieved ozone between 25 and 45 km is underestimated as a result of increased Mie scattering. On the other hand, an algorithm related effect causes the retrieved ozone below 25 km to be overestimated by an amount similar to the stratospheric deficit.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Geopysical Research Letters (ISSN 0094-8276); 22; 3; p. 235-238
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    Improved accuracy of radar WPMM estimated rainfall upon application of objective classification criteria (1995)
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    Publication Date: 2011-08-24
    Description: Application of the window probability matching method to radar and rain gauge data that have been objectively classified into different rain types resulted in distinctly different Z(sub e)-R relationships for the various classifications. These classification parameters, in addition to the range from the radar, are (a) the horizontal radial reflectivity gradients (dB/km); (b) the cloud depth, as scaled by the effective efficiency; (c) the brightband fraction within the radar field window; and (d) the height of the freezing level. Combining physical parameters to identify the type of precipitation and statistical relations most appropriate to the precipitation types results in considerable improvement of both point and areal rainfall measurements. A limiting factor in the assessment of the improved accuracy is the inherent variance between the true rain intensity at the radar measured volume and the rain intensity at the mouth of the rain guage. Therefore, a very dense rain gauge network is required to validate most of the suggested realized improvement. A rather small sample size is required to achieve a stable Z(sub e)-R relationship (standard deviation of 15% of R for a given Z(sub e)) -- about 200 mm of rainfall accumulated in all guages combined for each classification.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 34; 1; p. 212-223
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    Remote sensing and human health: new sensors and new opportunities (2000)
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    Publication Date: 2011-08-24
    Description: Since the launch of Landsat-1 28 years ago, remotely sensed data have been used to map features on the earth's surface. An increasing number of health studies have used remotely sensed data for monitoring, surveillance, or risk mapping, particularly of vector-borne diseases. Nearly all studies used data from Landsat, the French Systeme Pour l'Observation de la Terre, and the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer. New sensor systems are in orbit, or soon to be launched, whose data may prove useful for characterizing and monitoring the spatial and temporal patterns of infectious diseases. Increased computing power and spatial modeling capabilities of geographic information systems could extend the use of remote sensing beyond the research community into operational disease surveillance and control. This article illustrates how remotely sensed data have been used in health applications and assesses earth-observing satellites that could detect and map environmental variables related to the distribution of vector-borne and other diseases.
    Keywords: Earth Resources and Remote Sensing
    Type: Emerging infectious diseases (ISSN 1080-6040); Volume 6; 3; 217-27
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    Regolith Evolved Gas Analyzer (REGA): An Instrument to Characterize the Martian Soil Mineralogy and Atmosphere Composition (2000)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This abstract describes an instrument and experiment to be proposed for a future Mars surface mission to conduct basic research on environmental characterization. The Regolith Evolved Gas Analyzer (REGA) experiment is designed to provide information on Mars surface material properties in preparation for human missions of exploration. The goals of the investigation are: 1) Define and determine surface mineralogy of soil and dust and their effects on humans and machines; and 2) Conduct in-situ investigations aimed at identifying possible evidence of past or present life on Mars.
    Keywords: Instrumentation and Photography
    Type: Concepts and Approaches for Mars Exploration; Part 1; 148-149; LPI-Contrib-1062-Pt-1
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    Martian Neutron Energy Spectrometer (MANES) (2000)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: High energy charged particles of extragalactic, galactic, and solar origin collide with spacecraft structures and planetary atmospheres. These primaries create a number of secondary particles inside the structures or on the surfaces of planets to produce a significant radiation environment. This radiation is a threat to long term inhabitants and travelers for interplanetary missions and produces an increased risk of carcinogenesis, central nervous system (CNS) and DNA damage. Charged particles are readily detected; but, neutrons, being electrically neutral, are much more difficult to monitor. These secondary neutrons are reported to contribute 30-60% of the dose equivalent in the Shuttle and MIR station. The Martian atmosphere has an areal density of 37 g/sq cm primarily of carbon dioxide molecules. This shallow atmosphere presents fewer mean free paths to the bombarding cosmic rays and solar particles. The secondary neutrons present at the surface of Mars will have undergone fewer generations of collisions and have higher energies than at sea level on Earth. Albedo neutrons produced by collisions with the Martian surface material will also contribute to the radiation environment. The increased threat of radiation damage to humans on Mars occurs when neutrons of higher mean energy traverse the thin, dry Martian atmosphere and encounter water in the astronaut's body. Water, being hydrogeneous, efficiently moderates the high energy neutrons thereby slowing them as they penetrate deeply into the body. Consequently, greater radiation doses can be deposited in or near critical organs such as the liver or spleen than is the case on Earth. A second significant threat is the possibility of a high energy heavy ion or neutron causing a DNA double strand break in a single strike.
    Keywords: Instrumentation and Photography
    Type: Concepts and Approaches for Mars Exploration; Part 2; 213-214; LPI-Contrib-1062-Pt-2
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    Inflight Validation of AVIRIS Calibration in 1996 and 1997 (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) measures spectral radiance in the solar reflected spectrum from 400 to 2500 nm. Spectra are measured through 224 spectral channels with nominally 10-nm sampling and 10-nm full width at half maximum (FWHM). From a NASA ER-2 aircraft flying at 20,000 m altitude, these spectra are acquired as images with an 11-km width by up to 800-km length. The spatial sampling is 17 m, and the instantaneous field of view (IFOV) 20 m. The objective of AVIRIS is to acquire calibrated spectra that are used to derive properties of the Earth's land, water, and atmosphere for scientific research and environmental applications. To achieve this objective, the AVIRIS spectra must be calibrated. The AVIRIS sensor is calibrated in the laboratory before and after each flight season, however, the spectra acquired by AVIRIS for science investigators are acquired in the Q-bay of the ER-2 at 20 km altitude. The objective of the AVIRIS inflight calibration experiment is to validate the calibration of AVIRIS spectral images in the low pressure, low temperature operating environment of the ER-2. Inflight calibration experiments have been orchestrated for AVIRIS in every year of flight operations.
    Keywords: Instrumentation and Photography
    Type: Summaries of the Seventh JPL Airborne Earth Science Workshop January 12-16, 1998; Volume 1; 193-203; JPL-Publ-97-21-Vol-1
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    Minimum High Fire Temperatures Detected in AVIRIS Spectral Measurements from Brazil in 1995 (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: In August and September of 1995 the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) was deployed to Brazil as part of the NASA Smoke Cloud Aerosol and Radiation experiment in Brazil (SCAR-B). AVIRIS measures spectra from 400 to 2500 nm at 10-nm intervals. These spectra are acquired as images with dimensions of 11 by up to 800 km with 20-m spatial resolution. Spectral images measured by AVIRIS are spectrally, radiometrically, and spatially calibrated. During the SCAR-B deployment, AVIRIS measured more than 300 million spectra of regions of Brazil. A portion of these spectra were acquired over areas of actively burning fires. Actively burning fires emit radiance in the AVIRIS spectral range as a function of temperature. This emitted radiance is expressed from the 2500-nm end of the AVIRIS spectrum to shorter wavelengths as a function of intensity and modeled by the Planck function.. The objective of this research and analysis was to use spectroscopic methods to determine the minimum high temperature of the most intense fires measured in the SCAR-B AVIRIS data set. Spectra measured by AVIRIS with hot sources have been previously examined for volcanic lava and fires in Brazil.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Seventh JPL Airborne Earth Science Workshop January 12-16, 1998; Volume 1; 185-192A; JPL-Publ-97-21-Vol-1
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    Calibration Targets of the Southwest: Albedo and Homogeneity Comparisons Using AVIRIS Data (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Various locations in the southwestern U.S. are used to calibrate remote sensing instruments. This study shows how some of these targets compare in terms of albedo and homogeneity, and records the variation of these factors for a single location (Ivanpah Playa) over a period of one year. Results indicate that there is a great deal of variation among these targets in albedo, spectral flatness, and surface uniformity, and that these factors can change throughout the year.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Seventh JPL Airborne Earth Science Workshop January 12-16, 1998; Volume 1; 319-323; JPL-Publ-97-21-Vol-1
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    Thermal Stability of the AVIRIS On-Board Calibrator (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The AVIRIS On-Board Calibrator (OBC) provides essential data for refining the calibration of each AVIRIS data run. Annual improvement to the AVIRIS sensor and laboratory calibration accuracy has resulted in increasingly high demands on the stability of the OBC. Since the 1995 flight season, the OBC could track the stability of the spectrometer alignment to the 2% level, a significant improvement over previous years. The major contributor to this 2% stability was the conversion from a constant-current bulb power supply to an intensity-based active feedback power supply. Given the high sensor signal-to-noise ratio, improving the OBC to track 1% or 0.5% changes was highly desirable. Achieving stability better than 2% required an examination of the mechanisms affecting stability.
    Keywords: Instrumentation and Photography
    Type: Summaries of the Seventh JPL Airborne Earth Science Workshop January 12-16, 1998; Volume 1; 105-110; JPL-Publ-97-21-Vol-1
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    Evaluation of the Hydrodynamic Focusing Bioreactor (HDFB) and the Centrifugal Absorption Cartridge System (CACS) Performance Under Micro G (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The Hydrodynamic Focusing Bioreactor (HDFB) technology is designed to provide a flow field with nearly uniform shear force throughout the vessel, which can provide the desired low shear force spatial environment to suspend three-dimensional cell aggregates while providing optimum mass transfer. The reactor vessel consists of a dome-shaped cell culture vessel, a viscous spinner, an access port, and a rotating base. The domed vessel face has a radius of R(o). and rotates at 0mega(o) rpm, while the internal viscous spinner has a radius of R(i) and rotates at 0mega(i) rpm. The culture vessel is completely filled with cell culture medium into which three-dimensional cellular structures are introduced. The HDFB domed vessel and spinner were driven by two independent step motors,
    Keywords: Instrumentation and Photography
    Type: KC-135 and Other Microgravity Simulations; 62-64; NASA/CR-1999-208922
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    Coherent Doppler Lidar Data Products from Space-Based Platforms (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Coherent Doppler lidar is a promising technique for the global measurements of winds using a space-based platform. Doppler lidar produces estimates of the radial component of the velocity vector averaged over the resolution volume of the measurement. Profiles of the horizontal vector winds are produced by scanning the lidar beam or stepping the lidar beam through a sequence of different angles (step-stare). The first design for space-based measurements proposed a conical scan which requires a high power laser to produce acceptable signal levels for every laser pulse. Performance is improved by fixing the laser beam and accumulating the signal from many lidar pulses for each range-gate. This also improves the spatial averaging of the wind estimates and reduces the threshold signal energy required for a good estimate. Coherent Doppler lidar performance for space-based operation is determined using computer simulations and including the wind variability over the measurement volume as well as the variations of the atmospheric aerosol backscatter.
    Keywords: Instrumentation and Photography
    Type: Tenth Biennial Coherent Laser Radar Technology and Applications Conference; 298-301; NASA/CP-1999-209758
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    High-Efficiency Autonomous Coherent Lidar (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: A useful measure of sensor performance is the transceiver system efficiency n (sub sys). Which consists of the antenna efficiency n (sub a) and optical and electronic losses. Typically, the lidar equation and the antenna efficiency are defined in terms of the telescope aperture area. However, during the assembly of a coherent transceiver, it is important to measure the system efficiency before the installation of the beamexpanding telescope (i.e., the untruncated-beam system efficiency). Therefore, to accommodate both truncated and untruncated beam efficiency measurements, we define the lidar equation and the antenna efficiency in terms of the beam area rather than the commonly used aperture area referenced definition. With a well-designed Gaussian-beam lidar, aperture area referenced system efficiencies of 15 to 20 % (23-31% relative to the beam area) are readily achievable. In this paper we compare the differences between these efficiency definitions. We then describe techniques by which high efficiency can be achieved, followed by a discussion several novel auto alignment techniques developed to maintain high efficiency.
    Keywords: Instrumentation and Photography
    Type: Tenth Biennial Coherent Laser Radar Technology and Applications Conference; 247-250; NASA/CP-1999-209758
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    Stratified Volume Diffractive Optical Elements as Low-Mass Coherent Lidar Scanners (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Transmissive scanning elements for coherent laser radar systems are typically optical wedges, or prisms, which deflect the lidar beam at a specified angle and are then rotated about the instrument optical axis to produce a scan pattern. The wedge is placed in the lidar optical system subsequent to a beam-expanding telescope, implying that it has the largest diameter of any element in the system. The combination of the wedge diameter and asymmetric profile result in the element having very large mass and, consequently, relatively large power consumption required for scanning. These two parameters, mass and power consumption, are among the instrument requirements which need to be minimized when designing a lidar for a space-borne platform. Reducing the scanner contributions in these areas will have a significant effect on the overall instrument specifications, Replacing the optical wedge with a diffraction grating on the surface of a thin substrate is a straight forward approach with potential to reduce the mass of the scanning element significantly. For example, the optical wedge that will be used for the SPAce Readiness Coherent Lidar Experiment (SPARCLE) is approximately 25 cm in diameter and is made from silicon with a wedge angle designed for 30 degree deflection of a beam operating at approx. 2 micrometer wavelength. The mass of this element could be reduced by a factor of four by instead using a fused silica substrate, 1 cm thick, with a grating fabricated on one of the surfaces. For a grating to deflect a beam with a 2 micrometer wavelength by 30 degrees, a period of approximately 4 micrometers is required. This is small enough that fabrication of appropriate high efficiency blazed or multi-phase level diffractive optical gratings is prohibitively difficult. Moreover, bulk or stratified volume holographic approaches appear impractical due to materials limitations at 2 micrometers and the need to maintain adequate wavefront quality. In order to avoid the difficulties encountered in these approaches, we have developed a new type of high-efficiency grating which we call a Stratified Volume Diffractive Optical Element (SVDOE). The features of the gratings in this approach can be easily fabricated using standard photolithography and etching techniques and the materials used in the grating can be chosen specifically for a given application, In this paper we will briefly discuss the SVDOE technique and will present an example design of a lidar scanner using this approach. We will also discuss performance predictions for the example design.
    Keywords: Instrumentation and Photography
    Type: Tenth Biennial Coherent Laser Radar Technology and Applications Conference; 119-122; NASA/CP-1999-209758
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    Improving Scientific Capabilities in Space in the 21st Century: The NASA New Millennium Program (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: NASA's New Millennium Program (NMP) has been chartered to identify and validate in space emerging, revolutionary technologies that will enable less costly, more capable future science missions. The program utilizes a unique blend of science guidance and industry partnering to ferret out technology solutions to enable science capabilities in space which are presently technically infeasible, or unaffordable. Those technologies which present an unacceptably high risk to future science missions (whether small PI-led or operational) are bundled into technology validation missions. These missions seek to validate the technologies in a manner consistent with their future uses, thus reducing the associated risk to the first user, and obtaining meaningful science data as well. The Space Readiness Coherent Lidar Experiment (SPARCLE) was approved as the second NMP Earth Observing mission (EO2) in October 1997, and assigned to Marshall Space Flight Center for implementation. Leading up to mission confirmation, NMP sponsored a community workshop in March 1996 to draft Level-1 requirements for a doppler wind lidar mission, as well as other space-based lidar missions (such as DIAL). Subsequently, a study group was formed and met twice to make recommendations on how to perform a comparison of coherent and direct detection wind lidars in space. These recommendations have guided the science validation plan for the SPARCLE mission, and will ensure that future users will be able to confidently assess the risk profile of future doppler wind missions utilizing EO2 technologies. The primary risks to be retired are: (1) Maintenance of optical alignments through launch and operations on orbit, and (2) Successful velocity estimation compensation for the Doppler shift due to the platform motion, and due to the earth's rotation. This includes the need to account for all sources of error associated with pointing control and knowledge. The validation objectives are: (1) Demonstrate measurement of tropospheric winds from space using a scanning coherent Doppler lidar technique that scales to meet future research (e.g. ESSP) and operational (e.g. NPOESS) mission requirements. Specifically, produce and validate LOS wind data with single shot accuracy of 1-2 m/s in regions of high signal-to-noise ratio (SNR), and low atmospheric wind turbulence and wind shear, (2) Collect the atmospheric and instrument performance data in various scanning modes necessary to validate and improve instrument performance models that will enable the definition of future missions with greater confidence. Such data include aerosol backscatter data over much of the globe, and high SNR data such as that from surface returns, and (3) Produce a set of raw instrument data with which advanced signal processing techniques can be developed. This objective will permit future missions to better understand how to extract wind information from low backscatter regions of the atmosphere.
    Keywords: Instrumentation and Photography
    Type: Tenth Biennial Coherent Laser Radar Technology and Applications Conference; 38-39; NASA/CP-1999-209758
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    Ice Flow in the North East Greenland Ice Stream (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Early observations with ERS-1 SAR image data revealed a large ice stream in North East Greenland (Fahnestock 1993). The ice stream has a number of the characteristics of the more closely studied ice streams in Antarctica, including its large size and gross geometry. The onset of rapid flow close to the ice divide and the evolution of its flow pattern, however, make this ice stream unique. These features can be seen in the balance velocities for the ice stream (Joughin 1997) and its outlets. The ice stream is identifiable for more than 700 km, making it much longer than any other flow feature in Greenland. Our research goals are to gain a greater understanding of the ice flow in the northeast Greenland ice stream and its outlet glaciers in order to assess their impact on the past, present, and future mass balance of the ice sheet. We will accomplish these goals using a combination of remotely sensed data and ice sheet models. We are using satellite radar interferometry data to produce a complete maps of velocity and topography over the entire ice stream. We are in the process of developing methods to use these data in conjunction with existing ice sheet models similar to those that have been used to improve understanding of the mechanics of flow in Antarctic ice streams.
    Keywords: Earth Resources and Remote Sensing
    Type: Program for Arctic Regional Climate Assessment (PARCA); 16-19; NASA/TM-1999-209205
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    Interdisciplinary Determination of Ice Sheet Accumulation Patterns: Combined Atmospheric Modeling and Field and Remote Sensing Studies (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This research is focusing on two related areas that are fundamental to the NASA PARCA (Program for Arctic Regional Climate Assessment) program. The primary research area is the determination of the amount, rate, and timing of accumulation at distributed sites in the dry snow zone of Greenland and evaluation of these results in light of accumulation modeling results. The secondary research area is the calibration of the isotope "thermometer" at these ice sheet sites as well as the determination of long-term temperature trends in Greenland.
    Keywords: Earth Resources and Remote Sensing
    Type: Program for Arctic Regional Climate Assessment (PARCA); 60-62; NASA/TM-1999-209205
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    Strain Gauge Balance Uncertainty Analysis at NASA Langley: A Technical Review (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This paper describes a method to determine the uncertainties of measured forces and moments from multi-component force balances used in wind tunnel tests. A multivariate regression technique is first employed to estimate the uncertainties of the six balance sensitivities and 156 interaction coefficients derived from established balance calibration procedures. These uncertainties are then employed to calculate the uncertainties of force-moment values computed from observed balance output readings obtained during tests. Confidence and prediction intervals are obtained for each computed force and moment as functions of the actual measurands. Techniques are discussed for separate estimation of balance bias and precision uncertainties.
    Keywords: Instrumentation and Photography
    Type: First International Symposium on Strain Gauge Balances; Pt. 1; 279-306; NASA/CP-1999-209101/PT1
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    NASA Langley Research Center Force and Strain Measurement Capabilities (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Direct measurements of forces and moments are some of the most important data acquired during aerodynamic testing. This paper deals with the force and strain measurement capabilities at the Langley Research Center (LaRC). It begins with a progressive history of LaRC force measurement developments beginning in the 1940's and ends with the center's current capabilities. Various types of force and moment transducers used at LaRC are discussed including six-component sting mounted balances, semi-span balances, hinge moment balances, flow-through balances, rotor balances, and many other unique transducers. Also discussed are some unique strain-gage applications, such as those used in extreme environments. The final topics deal with the LaRC's ability to perform custom calibrations and our current levels of effort in the area of force and strain measurement.
    Keywords: Instrumentation and Photography
    Type: First International Symposium on Strain Gauge Balances; Pt. 1; 105-114; NASA/CP-1999-209101/PT1
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    Wind Lidar Edge Technique Shuttle Demonstration Mission: Anemos (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: A NASA mission is planned to demonstrate the technology for a wind lidar. This will implement the direct detection edge technique. The Anemos instrument will fly on the Space Transportation System (STS), or shuttle, aboard a Hitchhiker bridge. The instrument is being managed by the Goddard Space Flight Center as an in-house build, with science leadership from the GSFC Laboratory for Atmospheres, Mesoscale Atmospheric Processes Branch. During a roughly ten-day mission, the instrument will self calibrate and adjust for launch induced mis-alignments, and perform a campaign of measurements of tropospheric winds. The mission is planned for early 2001. The instrument is being developed under the auspices of NASA's New Millennium Program, in parallel with a comparable mission being managed by the Marshall Space Flight Center. That mission, called SPARCLE, will implement the coherent technique. NASA plans to fly the two missions together on the same shuttle flight, to allow synergy of wind measurements and a direct comparison of performance.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 939-942; NASA/CP-1998-207671/PT2
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    Performance Improvements to the Lidar Atmospheric Sensing Experiment (LASE) (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Lidar Atmospheric Sensing Experiment (LASE) is the first fully-engineered, modular, tunable, autonomous Differential Absorption Lidar (DIAL) system for the remote measurement of water vapor, aerosols and clouds across the troposphere. It was designed, built and environmentally tested at LARC. LASE was designed to fly aboard a NASA/Ames ER-2 aircraft (NASA's high altitude aircraft) and operate at altitudes from 58,000 to 70,000 feet. Since its first flight on May 11, 1994, it has flown 28 total missions on board the ER-2. LASE has been validated with results showing an accuracy better than the initial requirement for vertical profiles of water vapor in the troposphere. LASE can also deploy on several other aircraft including the NASA P-3 and will fly aboard the NASA DC-8 during the Convection And Moisture EXperiment (CAMEX) in July-September 1998. The tunable laser system of LASE was designed to operate in a double-pulse mode at 5Hz, with energy outputs of up to 15OmJ per pulse in the 813 to 819nm wavelength region and with 99% of the output energy within a spectral interval of 1.06 pm. Sixteen wavelengths were selected to cover the various water vapor absorption cross sections needed for the DIAL measurement. The Ti:Sapphire laser was constructed using a frequency-doubled Nd:YAG laser as the pump source and a single mode diode laser as a injection seeder for the Ti:Al2O3 laser. We have improved the LASE instrument in several important ways. Improvements to the seed source have demonstrated that DFB laser diodes can be used as reliable seed sources on airborne DIAL instruments. The DFB diode has enabled LASE to gather more data and significantly reduced the maintenance required to insure that the system performance requirements are met. The multiwavelength sequential seeding technique is the current method of data collection for LASE. It has the advantages of providing an entire atmospheric coverage of H2O(v) from the ground to the aircraft altitude along a single ground track. The development of a flight deployable system to measure spectral purity will insure that the LASE instrument or any future flight based DIAL system can meet the performance specifications to insure data accuracy.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 815-817; NASA/CP-1998-207671/PT2
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    Calibration of the Airborne Visible/Infrared Imaging Spectrometer in the Laboratory (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Imaging spectrometry data must be spectrally, radiometrically and geometrically calibrated in order to: 1) derive physical parameters from measured spectral radiance, 2) compare data acquired from different regions and at different times, 3) compare and analyze the imaging spectrometry data with data acquired from other calibrated sensors, and 4) compare and analyze data with results from computer models. The calibration of AVIRIS data is the process by which laboratory characterization data are applied to raw instrument data (digitized number versus spectral channels) to produce quantitative spectra (radiance versus wavelength) for each image pixel in units of spectral radiance. The AVIRIS sensor and calibration process are described by Vane and the application of the calibration data to the raw digital data is described by Green. This calibration process is validated for in-flight performance of the sensor using a rigorous ground-truth campaign. This workshop paper reviews the laboratory characterization data set that is used in the AVIRIS calibration process. The laboratory measurements used to acquire the calibration data are divided into three classes: 1) spectral calibration, 2) radiometric calibration, and 3) spatial calibration.
    Keywords: Instrumentation and Photography
    Type: Summaries of the Sixth Annual JPL Airborne Earth Science Workshop; Volume 1; 39-48; NASA/CR/96-113073
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    Mapping Volcanic Gas Emissions in the Mammoth Mountain Area Using AVIRIS (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The Long Valley Caldera located in the eastern Sierra Nevada (California) shows new signs of volcanic activity. This renewed activity is expressed by gas emissions, hydrothermal activity and frequent earthquakes. Analysis of the gas composition regarding the percentage biogenic carbon and the He-3/He-4 ratio revealed that the gas source is the magma body approximately 7 km beneath the Long Valley Caldera. The gas from the magma body surfaces not only via the fumaroles but also emerges along geological faults. Some of the spots where gas surfaces are marked by dead or stressed trees. Other spots may not yet be identified. It is only recently known, from research at 'Vulcano Island' in southern Italy, that volcanoes release abundant carbon dioxide from their flanks as diffuse soil emanations. Mammoth Mountain seems to behave in a similar manner. The research described in this paper is designed to determine whether AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) can be used to identify areas of volcanic gas emissions.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Sixth Annual JPL Airborne Earth Science Workshop; Volume 1; 75-81; NASA/CR/96-113073
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    Clock Requirements for Gamma-Ray Burst Localization Experiments (1997)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: Precise localization of gamma-ray bursts requires accurate timing information. A feasible space experiment places a number of detectors in the inner solar system with AU separations. To attain arcsecond positions, clock accuracy must be held to 1 millisecond. Mission costs are significantly reduced if the clock drift can be held to 1 millisecond over the entire mission, i.e. for several years.
    Keywords: Instrumentation and Photography
    Type: Proceedings of the Workshop on the Scientific Applications of Clocks in Space; 209-210; NASA/CR-97-112594
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    Ion-Atom Cold Collisions and Atomic Clocks (1997)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Collisions between ultracold neutral atoms have for some time been the subject of investigation, initially with hydrogen and more recently with laser cooled alkali atoms. Advances in laser cooling and trapping of neutral atoms in a Magneto-Optic Trap (MOT) have made cold atoms available as the starting point for many laser cooled atomic physics investigations. The most spectacularly successful of these, the observation of Bose-Einstein Condensation (BEC) in a dilute ultra-cold spin polarized atomic vapor, has accelerated the study of cold collisions. Experimental and theoretical studies of BEC and the long range interaction between cold alkali atoms is at the boundary of atomic and low temperature physics. Such studies have been difficult and would not have been possible without the development and advancement of laser cooling and trapping of neutral atoms. By contrast, ion-atom interactions at low temperature, also very difficult to study prior to modern day laser cooling, have remained largely unexplored. But now, many laboratories worldwide have almost routine access to cold neutral atoms. The combined technologies of ion trapping, together with laser cooling of neutrals has made these studies experimentally feasible and several very important, novel applications might come out of such investigations . This paper is an investigation of ion-atom interactions in the cold and ultra-cold temperature regime. Some of the collisional ion-atom interactions present at room temperature are very much reduced in the low temperature regime. Reaction rates for charge transfer between unlike atoms, A + B(+) approaches A(+) + B, are expected to fall rapidly with temperature, approximately as T(sup 5/2). Thus, cold mixtures of atoms and ions are expected to coexist for very long times, unlike room temperature mixtures of the same ion-atom combination. Thus, it seems feasible to cool ions via collisions with laser cooled atoms. Many of the conventional collisional interactions, exploited as a useful tool at room temperature and higher, are greatly enhanced at low energy. For example, collisional spin transfer from one species of polarized atoms to another has long been a useful method for polarizing a sample of atoms where no other means was available. Because optical pumping cannot be used to polarize the nuclear spin of Xe-129 or He-3 (for use in nmr imaging of the lungs), the nuclear spins are polarized via collisions with an optically pumped Rb vapor in a cell containing both gases. In another case, a spin polarized thermal Cs beam was used to polarize the hyperfine states of trapped He(+)-3 ions in order to measure their hyperfine clock transition frequency. The absence of an x-ray light source to optically pump the ground state of the He(+)-3 ion necessitated this alternative state preparation. Similarly, Cd(+) and Sr(+) ions were spin-oriented via collisions in a cell with optically pumped Rb vapor. Resonant RF spin changing transitions in the ground state of the ions were detected by changes in the Rb resonance light absorption. Because cold collision spin exchange rates scale with temperature as T(sup -1/2) this technique is expected to be a far more powerful tool than the room temperature counterpart. This factor of 100 or more enhancement in spin exchange reaction rates at low temperatures is the basis for a novel trapped ion clock where laser cooled neutrals will cool, state select and monitor the ion clock transition. The advantage over conventional direct laser cooling of trapped ions is that the very expensive and cumbersome UV laser light sources, required to excite the ionic cooling transition, are effectively replaced by simple diode lasers.
    Keywords: Instrumentation and Photography
    Type: Proceedings of the Workshop on the Scientific Applications of Clocks in Space; 153-161; NASA/CR-97-112594
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    Repeat Pass Aircraft Interferometry Results at Portage Lake, Maine and Innisfail, Australia (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The NASA/JPL AIRSAR/TOPSAR instruments have the capability of collecting fully polarimetric radar data at three wavelengths (C, L and P-Bands) and dual antenna interferometry at C-Band, and more recently L-Band. In order to understand frequency and baseline dependent scattering effects in vegetated regions repeat pass interferometry data was collected for two vegetated regions in 1993. Portage Lake, Maine is a primarily coniferous forested region with some clear cutting from logging activities in the region. The second site at Innisfail, Australia borders a tropical rain forest and is situated adjacent to some major clear cut regions and banana plantations. Preliminary analysis of repeat pass data collected in these areas shows that the smaller the wavelength the greater the temporal decorrelation between passes, the longer the wavelength the greater the penetration depth for some types of vegetation canopy, yet for some vegetation canopy types, in particular for a banana plantation there appears to be no frequency dependent penetration into the canopy.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Sixth Annual JPL Airborne Earth Science Workshop; Volume 2; 9-33; NASA/CR-96-112598
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    CERES and the S'COOL Project (1997)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The first Clouds and the Earth's Radiant Energy System (CERES) instrument will be launched on the Tropical Rainfall Measuring Mission (TRMM) spacecraft from a Japanese launch site in November 1997. This instrument is a follow-on to the Earth Radiation Budget Experiment (ERBE) begun in the 1980's. The instrument will measure the radiation budget - incoming and outgoing radiant energy - of the Earth. It will establish a baseline and look for climatic trends. The major feature of interest is clouds, which play a very strong role in regulating our climate. CERES will identify clear and cloudy regions and determine cloud physical and microphysical properties using imager data from a companion instrument. Validation efforts for the remote sensing algorithms will be intensive. As one component of the validation, the S'COOL (Students' Cloud Observations On-Line) project will involve school children from around the globe in making ground truth measurements at the time of a CERES overpass. Their observations will be collected at the NASA Langley Distributed Active Archive Center (DAAC) and made available over the Internet for educational purposes as well as for use by the CERES Science Team in validation efforts. Pilot testing of the S'COOL project began in January 1997 with two local schools in Southeastern Virginia and one remote site in Montana. This experience is helping guide the development of the S'COOL project. National testing is planned for April 1997, international testing for July 1997, and global testing for October 1997. In 1998, when the CERES instrument is operational, a global observer network should be in place providing useful information to the scientists and learning opportunities to the students.
    Keywords: Earth Resources and Remote Sensing
    Type: The Sixth Alumni Conference of the International Space University; 150-157; NASA-CP-3355
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    SIR-C Measurements of Soil Moisture, Vegetation and Surface Roughness and their Hydrological Application (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The objectives of the study are: (1) Analysis of SIR-C/X-SAR response to soil moisture, vegetation and surface roughness and development of an algorithm to retrieve these parameters; (2) Combination of the visible and near-infrared data and the SIR-C/X-SAR data to improve the range and accuracy of vegetation classification; (3) Testing of theoretical models for microwave propagation with SIR-C/X-SAR and microwave radiometric measurements over rough surfaces; and (4) Evaluation of a water balance model using SIR-C/X-SAR derived soil moisture values and other ancillary data. Progress, significant results and future plans are presented.
    Keywords: Earth Resources and Remote Sensing
    Type: Science Results from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR): Progress Report; 215-217; NASA/CR-97-206707
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    Radar Interferometric and Penetration Investigations using SIR-C Data (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Progress, significant results, publications and future plans are discussed in relation to the following objectives: (1) To model, experimentally characterize, and verify penetration phenomena in hyperarid and vegetated regions using the SIR-C/X-SAR multiparameter radar system and groundbased receivers; (2) To invert measured radar backscatter as a function of frequency and polarization in terms of geophysical parameters of the surface, subsurface and vegetation canopy such as surface roughness, subsurface geomorphology, or tree height and density; and (3) To display subsurface and within-canopy features in an image format, thus easing the interpretability of the results.
    Keywords: Earth Resources and Remote Sensing
    Type: Science Results from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR): Progress Report; 228-230; NASA/CR-97-206707
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  • 69
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    SIR-C/X-SAR: Imaging Radar Analyses for Forest Ecosystem Modeling (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Progress, significant results and future plans are discussed relating to the following objectives: (1) Ecosystem characterization using SIR-C/X-SAR and AirSAR data; (2) Improving radar backscatter models for forest canopies; and (3) Using SAR measurements and models with forest ecosystem models to improve inferences of ecosystem attributes and processes.
    Keywords: Earth Resources and Remote Sensing
    Type: Science Results from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR): Progress Report; 153-158; NASA/CR-97-206707
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  • 70
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    Differential Radar Interferometry (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Progress and future plans regarding the following objectives are presented: (1) Test differential radar interferometry as a new monitoring technique for remote sensing of a forest site, a farm site, and a desert site; and (2) Generate topographic maps of test sites from radar data.
    Keywords: Earth Resources and Remote Sensing
    Type: Science Results from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR): Progress Report; 66-67; NASA/CR-97-206707
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    Application of SIR-C SAR to Hydrology (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The progress, results and future plans regarding the following objectives are presented: (1) Determine and compare soil moisture patterns within one or more humid watersheds using SAR data, ground-based measurements, and hydrologic modeling; (2) Use radar data to characterize the hydrologic regime within a catchment and to identify the runoff producing characteristics of humid zone watersheds; and (3) Use radar data as the basis for scaling up from small scale, near-point process models to larger scale water balance models necessary to define and quantify the land phase of GCM's (Global Circulation Models).
    Keywords: Earth Resources and Remote Sensing
    Type: Science Results from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR): Progress Report; 43-47; NASA/CR-97-206707
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  • 72
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    The Galileo Tape Recorder Rewind Operation Anomaly (1997)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: On October 11, 1995, the Galileo spacecraft executed a sequence to record three approach images of Jupiter on the spacecraft's tape recorder, rewind the tape, and play back the images at the appropriate data rate consistent with the downlink performance. The recording of the images was performed and the spacecraft computer commanded the tape recorder to rewind the tape to the beginning of the first image. The rewind command was started at the proper time but the tape never got to the beginning of the image data. The analyses and tests that followed allowed a conclusive determination of the failure mechanism and indicated a strategy that could be used to prevent the untimely demise of the mission.
    Keywords: Instrumentation and Photography
    Type: Thirty-first Aerospace Mechanisms Symposium; 231-248; NASA-CP-3350
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  • 73
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    Facilities for Biological Research Aboard the International Space Station (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: A centrifuge designed as part of an integrated biological facility for installation onboard the International Space Station is presented. The requirements for the 2.5 m diameter centrifuge, which is designed for the support of biological experiments are discussed. The scientific objectives of the facility are to: provide a means of conducting fundamental studies in which gravitational acceleration is a controllable variable; provide a 1g control; determine the threshold acceleration for physiological response, and determine the value of centrifugation as a potential countermeasure for the biomedical problems associated with space flight. The implementation of the facility is reported on, and the following aspects of the facility are described: the host resources systems supply requirements such as power and data control; the habitat holding rack; the life sciences glove box; the centrifuge; the different habitats for cell culture, aquatic studies, plant research and insect research; the egg incubator, and the laboratory support equipment.
    Keywords: Instrumentation and Photography
    Type: ; 297-302
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  • 74
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    Repeat Pass Aircraft Interferometry Results at Portage Lake, Maine and Innisfail, Australia (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The NASA/JPL AIRSAR/TOPSAR instruments have the capability of collecting fully polarimetric radar data at three wavelengths (C, L, and P-bands) and dual antenna interferometry at C-band, and more recently, L-band. In order to understand frequency and baseline dependent scattering effects in vegetated regions, repeat pass interferometry data was collected for two vegetated regions in 1993. Portage Lake, Maine is a primarily coniferous forested region with some clear cutting from logging activities in the region. The second site at Innisfail, Australia borders a tropical rain forest and is situated adjacent to some major clear cut regions and banana plantations. Preliminary analysis of repeat pass data collected in these areas shows that the smaller the wavelength the greater the temporal decorrelation between passes, the longer the wavelength the greater the penetration depth for some types of vegetation canopy, yet for some vegetation canopy types, in particular for a banana plantation, there appears to be no frequency dependent penetration into the canopy.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Sixth Annual JPL Airborne Earth Science Workshop, March 4-8, 1996; Volume 2; 9-33; NASA-CR-203428
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    The Athena Pancam and Color Microscopic Imager (CMI) (2000)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The Athena Mars rover payload includes two primary science-grade imagers: Pancam, a multispectral, stereo, panoramic camera system, and the Color Microscopic Imager (CMI), a multispectral and variable depth-of-field microscope. Both of these instruments will help to achieve the primary Athena science goals by providing information on the geology, mineralogy, and climate history of the landing site. In addition, Pancam provides important support for rover navigation and target selection for Athena in situ investigations. Here we describe the science goals, instrument designs, and instrument performance of the Pancam and CMI investigations.
    Keywords: Instrumentation and Photography
    Type: Concepts and Approaches for Mars Exploration; Part 1; 15-16; LPI-Contrib-1062
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    Diurnal Reflectance Changes in Vegetation Observed with AVIRIS (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Among the most important short-term dynamic biological processes are diurnal changes in canopy water relations. Plant regulation of water transport through stomatal openings affects other gaseous transport processes, often dramatically decreasing photosynthetic fixation of carbon dioxide during periods of water stress. Water stress reduces stomatal conductance of water vapor through the leaf surface and alters the diurnal timing of stomatal opening. Under non-water stressed conditions, stomates typically open soon after dawn and transpire water vapor throughout the daylight period. During stress periods, stomates may close for part of the day, generally near mid-day. Under prolonged stress conditions, stomatal closure shifts to earlier times during the day; stomates may close by mid-morning and remain closed until the following morning - or remain closed entirely. Under these conditions the relationship between canopy greenness (e.g., measured with a vegetation index or by spectral mixture analysis) and photosynthetic fixation of carbon is lost and the remotely sensed vegetation metric is a poor predictor of gas exchange. Prediction of stomatal regulation and exchange of water and trace gases is critical for ecosystem and climate models to correctly estimate budgets of these gases and understand or predict other processes like gross and net ecosystem primary production. Plant gas exchange has been extensively studied by physiologists at the leaf and whole plant level and by biometeorologists at somewhat larger scales. While these energy driven processes follow a predictable if somewhat asymmetric diurnal cycle dependent on soil water availability and the constraints imposed by the solar energy budget, they are nonetheless difficult to measure at the tree and stand levels using conventional methods. Ecologists have long been interested in the potential of remote sensing for monitoring physiological changes using multi-temporal images. Much of this research has focused on day-to-day changes in water use, especially for agricultural applications. Ustin et al. showed seasonal changes in canopy water content in chaparral shrub could be estimated using optical methods. Vanderbilt et al. followed asymmetric diurnal changes in the reflectance of a walnut orchard, but could not attribute specific reflectance changes to specific changes in canopy architecture or physiology. Forests and shrub lands in California experience prolonged periods of drought, sometimes extending six months without precipitation. The conifer and evergreen chaparral communities common to the foothill region around the central valley of California retain their foliage throughout the summer and have low transpiration rates despite high net radiation and temperature conditions. In contrast, grasslands and drought resistant deciduous species in the same habitat are seasonally dormant in summer. Because of differences in the mechanisms of drought tolerance, rooting depth and physiology between different plant communities in the region, it is likely that they display differences in diurnal water relations. The presence of diverse plant communities provides an opportunity to investigate possible diurnal landscape patterns in water relations that could be observed by an airborne hyperspectral scanner. This investigation of AVIRIS data collected over forest and shrub land represents the continuation of a prior investigation involving spectral mixture analysis of diurnal effects in the same AVIRIS data set.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Seventh JPL Airborne Earth Science Workshop January 12-16, 1998; Volume 1; 399-408; JPL-Publ-97-21-Vol-1
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    On-Orbit Calibration of ADEOS OCTS with an AVIRIS Underflight (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The Ocean Color Temperature Scanner (OCTS) onboard the Advanced Earth Observation Satellite (ADEOS) was launched on August 17, 1996. Calibration of OCTS is required for use of the on-orbit measured data for retrieval of physical properties of the ocean. In the solar reflected portion of the electromagnetic spectrum, OCTS measures images with nominally 700-m spatial resolution through eight multispectral bands. The objective of this research was to establish the absolute radiometric calibration of OCTS on orbit through an underflight by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS is a NASA Earth-observing imaging spectrometer designed, built and operated by the Jet Propulsion Laboratory (JPL). AVIRIS acquires data from 20-km altitude on a NASA ER-2 aircraft, above most of the Earth's atmosphere. AVIRIS measures the solar reflected spectrum from 370 nm to 2500 nm through 224 contiguous spectral channels. The full width at half maximum (FWHM) of the spectral channels is nominally 10-nm. AVIRIS spectra are acquired as images of 11 km by up to 800 km extent with 20-m spatial resolution. The high spectral resolution of AVIRIS data allows direct convolution to the spectral response functions of the eight multispectral bands of OCTS. The high spatial resolution of AVIRIS data allows for spatial re-sampling of the data to match the ADEOS sensors spatial resolution. In addition, the AVIRIS high spatial resolution allows assessment of the scaling effects due to environmental factors of thin cirrus clouds, sub-pixel cloud cover, white caps, ocean foam, sun-glint, and bright-target adjacency. The platform navigation information recorded by AVIRIS allows calculation of the position and observation geometry of each spectrum for matching to the OCTS measurement. AVIRIS is rigorously characterized and calibrated in the laboratory prior to and following the flight season. The stability and repeatability of AVIRIS calibration have been validated through an extensive series of inflight calibration experiments. In the OCTS portion of the spectrum, using pre- and post-flight runway calibrations of AVIRIS coupled with the on-board calibrator an absolute calibration accuracy of better than 3% spectral, 2% radiometric, and 5% spatial, has been achieved. An analogous satellite underflight calibration experiment was performed with AVIRIS and the Optical Sensor (OPS) onboard the Japanese Earth Resources Satellite (JERS).
    Keywords: Instrumentation and Photography
    Type: Summaries of the Seventh JPL Airborne Earth Science Workshop January 12-16, 1998; Volume 1; 205-212G; JPL-Publ-97-21-Vol-1
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    Mapping Agricultural Crops with AVIRIS Spectra in Washington State (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Spectroscopy is used in the laboratory to measure the molecular components and concentrations of plant constituents to answer questions about the plant type, status, and health. Imaging spectrometers measure the upwelling spectral radiance above the Earth's surface as images. Ideally, imaging spectrometer data sets should be used to understand plant type, plant status, and health of plants in an agricultural setting. An Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data set was acquired over agricultural fields near Wallula, Washington on July 23rd, 1997. AVIRIS measures upwelling radiance spectra through 224 spectral channels with contiguous 10-nm sampling from 400 to 2500 nm in the solar-reflected spectrum. The spectra are measured as images of 11 by up to 800 km with 20-m spatial resolution. The spectral images measured by AVIRIS represent the integrated signal resulting from: the solar irradiance; two way transmittance and scattering of the atmosphere; the absorptions and scattering of surface materials; as well as the spectral, radiometric and spatial response functions of AVIRIS. This paper presents initial research to derive properties of the agricultural fields near Wallula from the calibrated spectral images measured by AVIRIS near the top of the atmosphere.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Seventh JPL Airborne Earth Science Workshop January 12-16, 1998; Volume 1; 213-220B; JPL-Publ-97-21-Vol-1
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    A Low Power Cryogenic Shutter Mechanism for Use in Infrared Imagers (2000)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This paper discusses the requirements, design, operation, and testing of the shutter mechanism for the Infrared Array Camera (IRAC). The shutter moves a mirror panel into or out of the incoming light path transitioning IRAC between data acquisition and calibration modes. The mechanism features a torsion flexure suspension system, two low-power rotary actuators, a balanced shaft, and a variable reluctance position sensor. Each of these items is discussed along with problems encountered during development and the implemented solutions.
    Keywords: Instrumentation and Photography
    Type: 34th Aerospace Mechanisms Symposium; 1-14; NASA/CP-2000-209895
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    Miniature Time-of-Flight Mass Spectrometer (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Major advances must occur to protect astronauts from prolonged periods in near-zero gravity and high radiation associated with extended space travel. The dangers of living in space must be thoroughly understood and methods developed to reverse those effects that cannot be avoided. Six of the seven research teams established by the National Space Biomedical Research Institute (NSBRI) are studying biomedical factors for prolonged space travel to deliver effective countermeasures. To develop effective countermeasures, each of these teams require identification of and quantitation of complex pharmacological, hormonal, and growth factor compounds (biomarkers) in humans and in experimental animals to develop an in-depth knowledge of the physiological changes associated with space travel. At present, identification of each biomarker requires a separate protocol. Many of these procedures are complicated and the identification of each biomarker requires a separate protocol and associated laboratory equipment. To carry all of this equipment and chemicals on a spacecraft would require a complex clinical laboratory; and it would occupy much of the astronauts time. What is needed is a small, efficient, broadband medical diagnostic instrument to rapidly identify important biomarkers for human space exploration. The Miniature Time-Of- Flight Mass Spectrometer Project in the Technology Development Team is developing a small, high resolution, time-of-flight mass spectrometer (TOFMS) to quantitatively measure biomarkers for human space exploration. Virtues of the JHU/APL TOFMS technologies reside in the promise for a small (less than one cubic ft), lightweight (less than 5 kg), low-power (less than 50 watts), rugged device that can be used continuously with advanced signal processing diagnostics. To date, the JHU/APL program has demonstrated mass capability from under 100 to beyond 10,000 atomic mass units (amu) in a very small, low power prototype for biological analysis. Further, the electronic nature of the TOFMS output makes it ideal for rapid telemetry to earth for in-depth analysis by ground support teams.
    Keywords: Instrumentation and Photography
    Type: National Space Biomedical Research Institute; B-111 - B-113
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    Pre-Launch End-to-End Testing Plans for the SPAce Readiness Coherent Lidar Experiment (SPARCLE) (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The SPAce Readiness Coherent Lidar Experiment (SPARCLE) mission was proposed as a low cost technology demonstration mission, using a 2-micron, 100-mJ, 6-Hz, 25-cm, coherent lidar system based on demonstrated technology. SPARCLE was selected in late October 1997 to be NASA's New Millennium Program (NMP) second earth-observing (EO-2) mission. To maximize the success probability of SPARCLE, NASA/MSFC desired expert guidance in the areas of coherent laser radar (CLR) theory, CLR wind measurement, fielding of CLR systems, CLR alignment validation, and space lidar experience. This led to the formation of the NASA/MSFC Coherent Lidar Technology Advisory Team (CLTAT) in December 1997. A threefold purpose for the advisory team was identified as: 1) guidance to the SPARCLE mission, 2) advice regarding the roadmap of post-SPARCLE coherent Doppler wind lidar (CDWL) space missions and the desired matching technology development plan 3, and 3) general coherent lidar theory, simulation, hardware, and experiment information exchange. The current membership of the CLTAT is shown. Membership does not result in any NASA or other funding at this time. We envision the business of the CLTAT to be conducted mostly by email, teleconference, and occasional meetings. The three meetings of the CLTAT to date, in Jan. 1998, July 1998, and Jan. 1999, have all been collocated with previously scheduled meetings of the Working Group on Space-Based Lidar Winds. The meetings have been very productive. Topics discussed include the SPARCLE technology validation plan including pre-launch end-to-end testing, the space-based wind mission roadmap beyond SPARCLE and its implications on the resultant technology development, the current values and proposed future advancement in lidar system efficiency, and the difference between using single-mode fiber optical mixing vs. the traditional free space optical mixing. attitude information from lidar and non-lidar sensors, and pointing knowledge algorithms will meet this second requirement. The topic of this paper is the pre-launch demonstration of the first requirement, adequate sensitivity of the SPARCLE lidar.
    Keywords: Instrumentation and Photography
    Type: Tenth Biennial Coherent Laser Radar Technology and Applications Conference; 156-159; NASA/CP-1999-209758
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    Comparison of Continuous Wave CO2 Doppler Lidar Calibration Using Earth Surface Targets in Laboratory and Airborne Measurements (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Routine backscatter, beta, measurements by an airborne or space-based lidar from designated earth surfaces with known and fairly uniform beta properties can potentially offer lidar calibration opportunities. This can in turn be used to obtain accurate atmospheric aerosol and cloud beta measurements on large spatial scales. This is important because achieving a precise calibration factor for large pulsed lidars then need not rest solely on using a standard hard target procedure. Furthermore, calibration from designated earth surfaces would provide an inflight performance evaluation of the lidar. Hence, with active remote sensing using lasers with high resolution data, calibration of a space-based lidar using earth's surfaces will be extremely useful. The calibration methodology using the earth's surface initially requires measuring beta of various earth surfaces simulated in the laboratory using a focused continuous wave (CW) CO2 Doppler lidar and then use these beta measurements as standards for the earth surface signal from airborne or space-based lidars. Since beta from the earth's surface may be retrieved at different angles of incidence, beta would also need to be measured at various angles of incidences of the different surfaces. In general, Earth-surface reflectance measurements have been made in the infrared, but the use of lidars to characterize them and in turn use of the Earth's surface to calibrate lidars has not been made. The feasibility of this calibration methodology is demonstrated through a comparison of these laboratory measurements with actual earth surface beta retrieved from the same lidar during the NASA/Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) mission on NASA's DC8 aircraft from 13 - 26 September, 1995. For the selected earth surface from the airborne lidar data, an average beta for the surface was established and the statistics of lidar efficiency was determined. This was compared with the actual lidar efficiency determined with the standard calibrating hard target.
    Keywords: Instrumentation and Photography
    Type: Tenth Biennial Coherent Laser Radar Technology and Applications Conference; 128-131; NASA/CP-1999-209758
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    CDDIS Data Center Summary (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This report summarizes the current and future plans of the Crustal Dynamics Data Information System (CDDIS) with respect to the International VLBI Service for Geodesy and Astrometry (IVS). Included are background information about the CDDIS, the computer architecture, staffing supporting the system, archive contents, and future plans for the CDDIS within the IVS.
    Keywords: Earth Resources and Remote Sensing
    Type: International VLBI Service for Geodesy and Astrometry: 1999 Annual Report; 173-176; NASA/TP-1999-209243
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    Strain Gages in use at NASA Langley: A Technical Review (1999)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: Surface mounted strain gages and strain gage application techniques are as varied as they are versatile. There is an abundance of technical literature, available throughout the strain gage community, offering techniques for installing strain gages and methods of obtaining useful information from them. This paper, while providing more of the same, will focus its discussions on recent Langley developments for using strain gages reliably and accurately in very harsh environments. With Langley's extensive use of wind tunnel balances, its ongoing effort in materials development, and its currently focused activities in structural testing, the use of strain gages in unusual and demanding environments has led to several innovative improvements in the "how to gage it" department. Several of these innovations will be addressed that hopefully will provide some practical information for the strain gage user who is finding the test environment and (or) the materials to be tested too demanding for previously utilized strain gage application technology. Specifically, this paper will include discussions in the following three areas: (1) technical considerations when gaging cryogenic wind tunnel balances, including areas for improving accuracy and reliability; (2) addressing technical difficulties associated with gaging composite test articles and certain alloys for testing at temperatures approaching -450F, or elevated temperatures up to 350F, or both temperatures inclusive during the same test scenario; (3) gaging innovations for testing metal/matrix and carbon/carbon composites at temperatures above 700F.
    Keywords: Instrumentation and Photography
    Type: First International Symposium on Strain Gauge Balances; Pt. 1; 413-429; NASA/CP-1999-209101/PT1
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    LASE measurements of convective boundary layer development during SGP97 (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The Southern Great Plains 1997 (SGP97) field experiment was conducted in Oklahoma during June-July 1997 to validate the models used for computing remote soil moisture using measurements by microwave radiometers. One of the objectives of SGP97 was to examine the effect of soil moisture on the evolution of the Atmospheric Boundary Layer (ABL) and clouds over the Southern Great Plains (SGP) during the warm season. The LASE (Lidar Atmospheric Sensing Experiment) airborne DIAL (Differential Absorption Lidar) system, which was flown autonomously on the NASA ER-2 aircraft during previous missions, was reconfigured to fly on the NASA P3 research aircraft. During SGP97 LASE was used to study the morning evolution of the ABL, particularly as manifested in the development of the convective boundary layer, and to study the influence of soil moisture variations on the development of ABL. The ABL development is strongly influenced by the surface energy budget, which is in turn influenced by soil moisture, mesoscale meteorology, clouds, and solar insolation. LASE data acquired during this mission are being used to study the ABL water vapor budget, the development of the ABL, spatial and temporal variabilities in the ABL, and the meteorological factors that influence the ABL development. This field experiment also permitted comparisons of LASE water vapor measurements with water vapor profiles acquired by radiosondes launched at the DOE (Department of Energy) Atmospheric Radiation Measurement (ARM) Southern Great Plain (SGP) site and at NASA/Wallops Flight Facility, as well as with measurements from other SGP97 aircraft.
    Keywords: Earth Resources and Remote Sensing
    Type: Nineteenth International Laser Radar Conference; 261-264; NASA/CP-1998-207671/PT1
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    Increased Capabilities for Conventional Lidars using Holographic Optics (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: While the field of holographic optics is relatively new, and numerous applications are still being devised and tested, there are good prospects that the use of holographic optical elements (HOEs) may revolutionize the design and applications of optical systems in various fields. This paper is not a review of HOE developments, but rather an account of a particular application, namely the extension of the scanning capabilities of conventional telescopes-in particular, lidar receivers-by means of special holographic accessories. As originally described and in a patent, and in several subsequent publications the HOE lidar was based on the concept of building into the holographic element (either a transmitting one or a reflecting one) all the optical power needed to focus a lidar return to a detector at the HOE's focal point, as well as subjecting the lidar return to both angular deflection and wavelength selection. Results will be reported on the use of Holographic Transmission Gratings (HTGs) at 532 nm and 770 nm at 45 deg. cone angle, both in the laboratory and in the atmosphere at Utah State University.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 923-924; NASA/CP-1998-207671/PT2
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  • 87
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    Multi-Beam Surface Lidar for Lunar and Planetary Mapping (1998)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: Surface lidar techniques are now being demonstrated in low Earth orbit with a single beam of pulsed laser radiation at 1064 nm that profiles the vertical structure of Earth surface landforms along the nadir track of a spacecraft. In addition, a profiling laser altimeter, called MOLA, is operating in elliptical Martian orbit and returning surface topography data. These instruments form the basis for suggesting an improved lidar instrument that employs multiple beams for extension of sensor capabilities toward the goal of true, 3-dimensional mapping of the Moon or other similar planetary surfaces. In general the lidar waveform acquired with digitization of a laser echo can be used for laser distance measurement (i.e. range-to-the-surface) by time-of-flight measurement and for surface slope and shape measurements by examining the detailed lidar waveform. This is particularly effective when the intended target is the lunar surface or another planetary body free of any atmosphere. The width of the distorted return pulse is a first order measure of the surface incidence angle, a combination of surface slope and laser beam pointing. Assuming an independent and absolute (with respect to inertial space) measurement of laser beam pointing on the spacecraft, it is possible to derive a surface slope with-respect-to the mean planetary surface or its equipotential gravity surface. Higher-order laser pulse distortions can be interpreted in terms of the vertical relief of the surface or reflectivity variations within the area of the laser beam footprint on the surface.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 927-928; NASA/CP-1998-207671/PT2
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  • 88
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    Characterization of an Ozone DIAL Receiver for Operation on an Unpiloted Atmospheric Vehicle (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Laser remote sensing from aircraft has become a very important technique for observing ozone in the environment. NASA Langley has an active aircraft based research program which presently uses Nd:YAG-pumped dye lasers that are then doubled into the UV to probe both the stratosphere and troposphere for ozone using the differential absorption lidar (DIAL) technique. This large system can only fly on large (NASA DC-8, Electra) aircraft and has been deployed on many missions throughout the world. In the future it will be desirable to fly autonomous, lightweight, compact ozone DIAL instruments on unpiloted atmospheric vehicles (UAV) aircraft. Such aircraft could fly at high altitudes for extended times collecting science data without risk to the operator. Cost for such missions may be substantially reduced over present large aircraft based missions. Presently there are no ozone DIAL systems capable of flying on an UAV aircraft. In order to facilitate UAV missions, small more efficient laser transmitters need to be developed that emit approximately 25mJ near 300nm for each of the DIAL 'on' and 'off' line pulses. Also lightweight, compact DIAL receiver systems need to be built and demonstrated. Such receiver systems may incorporate fiber optic coupled telescopes for maximum light gathering capability per unit area, high quantum efficiency gated photomultiplier tubes with reasonable gain and very narrow-band filters for background light rejection with high light throughput. A compact high-performance 16-bit digitizer and a data storage system are also required. A conceptional design of such a UAV DIAL instrument is presented. Here a pulsed UV laser emits pulses into the atmosphere where elastic scattering occurs which results in light being scattered into the receiver telescope. The subject of this paper is the design, construction and testing of a robust, compact ozone DIAL receiver system that would be a prototype for eventual use in a UAV aircraft.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 919-922; NASA/CP-1998-207671/PT2
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    Capacitively Stabilized Etalon Technology for Spaceborne Wind Lidar Application (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Global monitoring by satellites is important for many types of environmental studies. Among these, the wind field is the single most important atmospheric state variable required for understanding atmospheric motion and predicting weather. Studies indicate that a global determination of the tropospheric wind field to an accuracy of 1-5 m/sec is critical for improved numerical weather forecasting. This measurement could be carried out with a spaceborne lidar system sensing the Doppler shift of a laser signal backscattered from the atmosphere. Over the past four years we have developed a ground-based Edge Technique lidar system and demonstrated wind measurements through the troposphere with high accuracy (1-6 m/s) and high spatial resolution. Recently, we began the design of a shuttle based wind measurement system for technology demonstration as part of the Zephyr program. In this paper, we present the characteristics of the high spectral resolution etalon filter technology for lidar wind measurement with the Edge Technique. In conclusion, a spacecraft motion compensation method has been discussed. We demonstrated experimentally that the etalon can be tuned to compensate for any satellite induced Doppler shift to an accuracy of better than 0.6 m/s over a time period of 2.5 ms.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 915-918; NASA/CP-1998-207671/PT2
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    Operation of the Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing (PHASERS) (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This study represents the first successful employment of the Holographic Optical Telescope and Scanner (HOTS) technology to make atmospheric backscattering measurements in a scanning mode. In several independent attempts the system successfully detected the return signal from atmospheric structures as they moved across the field-of-view (FOV) of the rotating Holographic Optical Element (HOE). Future plans include the addition of a narrow band filter and the necessary optics for day-time measurements, along with additional automation of the system and its data handling. In part, due to the success of this demonstration of the HOTS technology a new class of light weight scanning telescopes for lidar remote sensing from air and space craft platforms are under development and being tested for additional applications.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 879-882; NASA/CP-1998-207671/PT2
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    Atmospheric Depolarization Lidar Experimental Receiver: A Space Shuttle Hitchhiker Payload (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Development work is underway at the Goddard Space Flight Center to construct a depolarization measuring atmospheric lidar receiver. The Atmospheric Lidar (AL) is tentatively scheduled to fly on the Space Shuttle in a late-1999 time frame. The AL will fly in conjunction with the Shuttle Laser Altimeter (SLA) and the Infrared Spectral Imaging Radiometer (ISIR) to provide a comprehensive package of atmospheric aerosol and cloud information. The AL operates in conjunction with the SLA laser transmitter and measures profiles of atmospheric backscatter at 532 nm. The receiver system discriminates between the parallel and perpendicular polarizations of the backscattered signal, thus providing depolarization ratios for scattering from clouds. The lidar receiver also provides cloud height and thickness measurements to complement the brightness temperature measurements generated by the ISIR thermal imager. The function of the AL is twofold. The primary function is to provide range-resolved measurements of atmospheric aerosol backscatter and depolarization ratio at 532 nm with 75 m vertical resolution. The scientific purpose of these measurements is to determine composition of clouds based on the depolarization ratio (i.e cloud content is water or ice), to determine cloud height and thickness, and to gain further understanding of the global distribution of aerosols. This information, when coupled with the cloud brightness measured by the ISIR thermal imager will provide a significant amount of information on cloud composition and radiative effects, particularly for cirrus and sub-visual cirrus clouds. A secondary function of the AL is to serve as an in-space test bed for lidar technology advancements, including a fully fiber-coupled receiver and photon counting from space. In addition, the data obtained by the AL will be used to develop software for the Geoscience Laser Altimeter System (GLAS) flight mission.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 875-877; NASA/CP-1998-207671/PT2
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    Characterization of a 16-bit Digitizer System for Lidar Data Acquisition (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: A new 16-bit 6-MHz compact, lightweight waveform digitizer module has been tested using actual 300-nm lidar atmospheric returns. The noise level of this digitizer was tested and found to be substantially below the ozone number density to be measured. The digitizer is inexpensive and compact enough to be deployed in UAV aircraft and spacecraft environments. With 16-bit digitizers a resolution of 0.046 mV/step can be achieved, substantially improving resolution over 12-bit systems. This digitizer will find widespread use in future DIAL receiver systems.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 863-866; NASA/CP-1998-207671/PT2
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    Conversions to the Lidar Atmospheric Sensing Experiment (LASE) Instrument for Nadir and Zenith Measurements (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: LASE now has the advantage of being economically upgraded and customized with COTS hardware and software while using "C" software language. These changes are made so as not to destroy the form, fit and functional characteristics required for flights aboard the ER-2 aircraft. The LASE Instrument can now be quickly adapted to fly onboard ER-2, P-3, C-130 and DC-8 aircraft. The adaptability of the CDS upgraded electronics compliments other modular subsystems like the laser optical bench in that it was designed to be a test bed for new technology lasers.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 819-821; NASA/CP-1998-207671/PT2
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    Design and Operational Characteristics of the Shuttle Coherent Wind Lidar (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: NOAA has identified the measurement of atmospheric wind velocities as one of the key unmet data sets for its next generation of sensing platforms. The merits of coherent lidars for the measurement of atmospheric winds from space platforms have been widely recognized; however, it is only recently that several key technologies have advanced to a point where a compact, high fidelity system could be created. Advances have been made in the areas of the diode-pumped, eye-safe, solid state lasers and room temperature, wide bandwidth, semiconductor detectors operating in the near-infrared region. These new lasers can be integrated into efficient and compact optical systems creating new possibilities for the development of low-cost, reliable, and compact coherent lidar systems for wind measurements. Over the past five years, the University of Alabama in Huntsville (UAH) has been working toward further advancing the solid state coherent lidar technology for the measurement of atmospheric winds from space. As part of this effort, UAH had established the design characteristics and defined the expected performance for three different proposed space-based instruments: a technology demonstrator, an operational prototype, and a 7-year lifetime operational instrument. SPARCLE is an ambitious project that is intended to evaluate the suitability of coherent lidar for wind measurements, demonstrate the maturity of the technology for space application, and provide a useable data set for model development and validation. This paper describes the SPARCLE instrument's major physical and environmental design constraints, optical and mechanical designs, and its operational characteristics.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 703-706; NASA/CP-1998-207671/PT2
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    Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Scanning holographic lidar receivers are currently in use in two operational lidar systems, PHASERS (Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing) and now HARLIE (Holographic Airborne Rotating Lidar Instrument Experiment). These systems are based on volume phase holograms made in dichromated gelatin (DCG) sandwiched between 2 layers of high quality float glass. They have demonstrated the practical application of this technology to compact scanning lidar systems at 532 and 1064 nm wavelengths, the ability to withstand moderately high laser power and energy loading, sufficient optical quality for most direct detection systems, overall efficiencies rivaling conventional receivers, and the stability to last several years under typical lidar system environments. Their size and weight are approximately half of similar performing scanning systems using reflective optics. The cost of holographic systems will eventually be lower than the reflective optical systems depending on their degree of commercialization. There are a number of applications that require or can greatly benefit from a scanning capability. Several of these are airborne systems, which either use focal plane scanning, as in the Laser Vegetation Imaging System or use primary aperture scanning, as in the Airborne Oceanographic Lidar or the Large Aperture Scanning Airborne Lidar. The latter class requires a large clear aperture opening or window in the aircraft. This type of system can greatly benefit from the use of scanning transmission holograms of the HARLIE type because the clear aperture required is only about 25% larger than the collecting aperture as opposed to 200-300% larger for scan angles of 45 degrees off nadir.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 623-626; NASA/CP-1998-207671/PT2
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    First results from the aerosol lidar and backscatter sonde intercomparison campaign STRAIT'1997 at table mountain facility during February-March 1997 (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: First results of an intercomparison measurement campaign between three aerosol lidar instruments and in-situ backscatter sondes performed at Table Mountain Facility (34.4 deg N, 117.7 deg E, 2280 m asl) in February-March 1997 are presented. During the campaign a total of 414 hours of lidar data were acquired by the Aerosol-Temperature-Lidar (ATL, Goddard Space Flight Center) the Mobile-aerosol-Raman-Lidar (MARL, Alfred Wegener Institute), and the TMF-Aerosol-Lidar (TAL, Jet Propulsion Laboratory), and four backscatter sondes were launched. From the data set altitude profiles of backscatter ratio and volume depolarization of stratospheric background aerosols at altitudes between 15 and 25 km and optically thin high-altitude cirrus clouds at altitudes below 13 km are derived. On the basis of a sulfuric acid aerosol model color ratio profiles obtained from two wavelength lidar data are compared to the corresponding profiles derived from the sonde observations. We find an excellent agreement between the in-situ and ATL lidar data with respect to backscatter and color ratio. Cirrus clouds were present on 16 of 26 nights during the campaign. Lidar observations with 17 minute temporal and 120-300 m spatial resolution indicate high spatial and temporal variability of the cirrus layers. Qualitative agreement is found between concurrent lidar measurements of backscatter ratio and volume depolarization.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; 477-480; NASA/CP-1998-207671/PT1
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    Upper tropospheric water vapor: A field campaign of two Raman lidars, Airborne hygrometers, and Radiosondes (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Water vapor in the atmosphere plays an important role in radiative transfer and the process of radiative balance so critical for understanding global change. It is the principal ingredient in cloud formation, one of the most difficult atmospheric processes to model, and the most variable component of the Earth-atmosphere albedo. And as a free molecule, it is the most active infrared absorber and emitter, thus, the most important greenhouse gas. The radiative impact of water vapor is important at all levels of the atmosphere. Even though moisture decreases by several orders-of-magnitude from the Earth's surface to the tropopause, recent research has shown that, from a radiative standpoint, a small percentage change in water vapor at any level is nearly equivalent. Therefore accurate and precise measurements of this important atmospheric constituent are needed at all levels to evaluate the full radiative impact. The need for improved measurements in the upper troposphere is particularly important because of the generally hostile (very dry and cold) conditions encountered. Because of the importance of water vapor to the understanding of radiative transfer, the Department of Energy's Atmospheric Radiation Measurements (ARM) program initiated a series of measurement campaigns at the Cloud And Radiation Testbed (CART) site in Oklahoma, especially focused on atmospheric water vapor. Three water vapor intensive observation period (water vapor IOP) campaigns were planned. Two of the water vapor IOP campaigns have been completed: the first IOP was held during the fall of 1996 with a focus on boundary layer water vapor measurements, and the second was conducted during the fall of 1997 with a focus on both boundary layer moisture e and moisture in the upper troposphere. This paper presents a review of the intercomparisons of water vapor measurements in the upper troposphere aquired during the second water vapor IOP. Data to be presented include water vapor measurements ements from: two Raman Lidars, the NASA Goddard Scanning Raman Lidar (SRL) and the CART Raman Lidar (CARL), a number of Vaisala radiosondes launched during the IOP campaign, and a dew point hygrometer flown on the University of North Dakota Cessna Citation Aircraft.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; 367-370; NASA/CP-1998-207671/PT1
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    Comparison of measurements by the NASA/GSFC scanning raman lidar and the DOE/ARM CART raman lidar (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Latent heat transfer through evaporation and condensation of water vapor is the most important energy transport mechanism in the atmosphere. In addition, water vapor is the most active greenhouse gas. Any global warming scenario must take accurate account of the spatial and temporal variation of water vapor in order to account for both of these effects. Due to the great importance of water vapor in atmospheric radiation studies, specific intensive operations periods (IOPs) have been hosted by the Department of Energy's Atmospheric Radiation Measurements (ARM) program. One of the goals of these IOPs has been to determine the quality of and explain any discrepancies among a wide variety of water vapor measuring instruments. Raman lidar systems developed by NASA/Goddard Space Flight Center and DOE/Sandia National Laboratories have participated in the two Water Vapor IOPs (WVIOPs) held at the Southern Great Plains (SGP) Cloud and Radiation Testbed Site (CART) site during 1996 (WVIOP1) and 1997 (WVIOP2). Detailed comparisons of these two systems is ongoing but this effort has already resulted in numerous improvements in design and data analysis for both lidar systems.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; 285-288; NASA/CP-1998-207671/PT1
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  • 99
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    Examination of Biomass Fire Temperature and Areal Extent from Calibrated AVIRIS Spectra (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Biomass burning is an important process on the Earth at the local, regional and global scales. To investigate issues related to biomass burning, a range of remotely acquired data were measured as part of the NASA Smoke Cloud Aerosol and Radiation experiment in Brazil, 1995. As part of this experiment, images of calibrated spectral radiance from 400 to 2500 nm at 10 nm intervals were acquired by AVIRIS. To investigate the expression of biomass fires in AVIRIS spectra, a model of the upwelling radiance from a burning fire was developed. This spectral model accounts for four components in the 20 by 20 m AVIRIS spatial resolution element. These are: (1) the atmospheric path radiance, (2) the solar reflected radiance from unburnt vegetation and soil, (3) the apparent temperature and area of a primary fire, and (4) the apparent temperature and area of a secondary fire. A nonlinear least squares spectral fitting algorithm was developed to invert this model for the AVIRIS spectra. The derived biomass burning parameters from this algorithm are presented for AVIRIS spectral images acquired over Cuiaba, Brazil on 25 August 1995.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Sixth Annual JPL Airborne Earth Science Workshop; Volume 1; 105-113; NASA/CR/96-113073
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  • 100
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    Surveying Dead Trees and CO2-Induced Stressed Trees Using AVIRIS in the Long Valley Caldera (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Since 1980 the Long Valley Caldera in the eastern Sierra Nevada (California) has shown signs of renewed volcanic activity. Frequent earthquakes, a re-inflation of the caldera, hydrothermal activity and gas emissions are the outer symptoms of this renewed activity. In 1990 and 1991 several areas of dying trees were found around Mammoth Mountain. The cause of the die off of the trees was first sought in the persistent drought in the preceding years. However, the trees died regardless of age and species. Farrar et al. (1995) started a soil-gas survey in 1994 in the dead-tree areas and found carbon dioxide concentrations ranging from 30 to 96% at soil depths between 30 and 60 cm. CO2 concentrations in the atmosphere are usually around 0.03% and in the soil profile CO2 levels do commonly not exceed 4 to 5%. Although not much is known about the effect of high levels of carbon dioxide in the soil profile on roots, it is most likely that the trees are dying due to oxygen deprivation: the CO2 drives the oxygen out of the soil. So far, four sites of dead trees have been mapped around Mammoth Mountain. The two largest dying trees sites are located near Horseshoe Lake and near Mammoth Mountain Main Lodge covering approximately an area of 10 and 8 ha respectively. Analysis of the gas composition regarding the He-3/He-4 ratio and the percentage biogenic carbon reveals the source of the gas: the magma body beneath the Long Valley Caldera. Until recently it was not known that volcanoes release abundant carbon dioxide from their flanks as diffuse soil emanations. As a result of the magma gas emission around Mammoth Mountain there is an excellent sequence of dead trees, stressed trees, healthy trees and bare soil surfaces. This research site provides excellent opportunities to: (1) Study the capabilities of imaging spectrometry to map stressed (and dead) pine and fir species; (2) Study methods to separate the vivid vegetation, stressed vegetation and dead vegetation from the soil background of glacial deposits and crystalline rocks. The dead tree areas are located on the flanks of Mammoth Mountain (N:37 deg 37' 45" and W:119 deg 02' 05") at an elevation between 2600 and 3000 meters. The area is covered by an open type of Montane Forest. The dominant tree species are Lodgepole Pine (Pinus contorta), the Red Fir (Abies magnifica) and the Jeffrey Pine (Pinus jeffreyi). The soil surface near Horseshoe Lake is generally fairly bright. The surface is covered by glacial deposits (till) consisting mainly of weathered granitic rocks.
    Keywords: Earth Resources and Remote Sensing
    Type: Summaries of the Sixth Annual JPL Airborne Earth Science Workshop; Volume 1; 67-73; NASA/CR/96-113073
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