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  • GEOPHYSICS  (968)
  • 1995-1999
  • 1985-1989  (968)
  • 1950-1954
  • 1985  (968)
  • 1
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    Seismic analysis of the large 70-meter antenna, part 1: Earthquake response spectra versus full transient analysis (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: As a check on structure safety aspects, two approaches in seismic analysis for the large 70-m antennas are presented. The first approach, commonly used by civil engineers, utilizes known recommended design response spectra. The second approach, which is the full transient analysis, is versatile and applicable not only to earthquake loading but also to other dynamic forcing functions. The results obtained at the fundamental structural frequency show that the two approaches are in good agreement with each other and both approaches show a safe design. The results also confirm past 64-m antenna seismic studies done by the Caltech Seismology Staff.
    Keywords: GEOPHYSICS
    Type: The Telecommun. and Data Acquisition Progr. Rept.; p 31-42
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  • 2
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    Theoretical and experimental design studies for the Atmospheric General Circulation Experiment (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: The major criterion for the Atmospheric General Circulation Experiment (AGCE) design is that it be possible to realize strong baroclinic instability in the spherical configuration chosen. A configuration was selected in which a hemispherical shell of fluid is subjected to latitudinal temperature gradients on its spherical boundaries and the latitudinal boundaries are insulators. Work in the laboratory with a cylindrical version of this configuration revealed more instabilities than baroclinic instability. Since researchers fully expect these additional instabilities to appear in the spherical configuration also, they decided to continue the laboratory cylindrical annulus studies. Four flow regimes were identified: an axisymmetric Hadley circulation, boundary layer convection, baroclinic waves and deep thermal convection. Regime diagrams were prepared.
    Keywords: GEOPHYSICS
    Type: NASA(MSFC FY-85 Atmospheric Processes Research Review; 2 p
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  • 3
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    The use of satellite data in understanding and predicting convective and large-scale dynamical processes (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A two-layer truncated baroclinic spectral model was developed to study the long-term evolution of disturbances to a baroclinically unstable mean flow. Topography and crudely-parameterized radiative processes were accounted for. As a result of Robert Schlaak's discovery of the underlying barotropic nature of the index oscillation as well as reviewers suggestions about the original manuscript, the model has been revised to allow for barotropic as well as baroclinic wave-mean flow interactions. The form-drag exerted by the topography on the barotropic part of the mean flow is larger than on the baroclinic part and thus researchers anticipate significant changes from the original calculations on the index oscillation when it is strongly modulated by topography. Researchers believe that since the index oscillation accounts for a significant portion of atmospheric temporal variance, the long term predictability could be improved if reliable forecasts of the index oscillation were available. Two spectral models of the index oscillation, one barotropic and the other baroclinic, have been developed. The latter allows for moisture, radiation, land-sea temperature countrasts, and energy exchanges with the underlying surface.
    Keywords: GEOPHYSICS
    Type: NASA. Marshall Space Flight Center NASA(MSFC FY-85 Atmospheric Processes Research Review; 2 p
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  • 4
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    Age-dating volcanic and alluvial surfaces with multipolarization data (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A false-color multipolarization version of one of the images of Owens Valley area acquired by the JPL Synthetic Aperture Radar (SAR) is given. A geologic map of the alluvial fans there (Gillespie, 1982) is also given for comparison. In general, brightness in the multipolarization images can be seen to be inversely proportional to the age of the surfaces. A more detailed investigation of the relationship between backscatter and age of the surfaces was undertaken with calibrated aircraft SAR data. The quantitative relationship between backscatter coefficient and age for the three polarizations is shown. The straight lines connecting the measured data points imply a steady-state process, although the process or processes leading to this relationship may have operated at rates that varied with climate fluctuations, such as the glacial ages. It is expected that the relationship between radar brightness and age is a consistent one, and that with the wider availability of calibrated radar backscatter data, these relationships can be less well-known areas. The effect of variable such as past climate fluctuations, tectonic disturbance, and rock type must be understood before extension beyond the Mojave Desert region can be attempted.
    Keywords: GEOPHYSICS
    Type: NASA(JPL Aircraft SAR Workshop Proc.; p 31-36
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  • 5
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    Mobile VLBI and GPS measurement of vertical crustal motion (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Mobile Very Long Base Interferometry (VLBI) and Global Positioning System (GPS) geodetic measurements have many error sources in common. Calibration of the effects of water vapor on signal transmission through the atmosphere, however, remains the primary limitation to the accuracy of vertical crustal motion measurements made by either technique. The two primary methods of water vapor calibration currently in use for mobile VLBI baseline measurements were evaluated: radiometric measurements of the sky brightness near the 22 GHz emission line of free water molecules and surface meteorological measurements used as input to an atmospheric model. Based upon a limited set of 9 baselines, it is shown that calibrating VLBI data with water vapor radiometer measurements provides a significantly better fit to the theoretical decay model than calibrating the same data with surface meteorological measurements. The effect of estimating a systematic error in the surface meteorological calibration is shown to improve the consistency of the vertical baseline components obtained by the two calibration methods. A detailed error model for the vertical baseline components obtained indicates current mobile VLBI technology should allow accuracies of order 3 cm with WVR calibration and 10 cm when surface meteorological calibration is used.
    Keywords: GEOPHYSICS
    Type: The Telecommun. and Data Acquisition Progr. Rept.; p 185-198
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  • 6
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    Theoretical and experimental studies in support of the geophysical fluid flow experiment (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Meteorologists and astrophysicists interested in large scale planetary and solar circulations have come to recognize the importance of rotation and stratification in determining the character of these flows. In particular, the effect of latitude-dependent Coriolis force on nonlinear convection is thought to play a crucial role in such phenomena as differential rotation on the Sun, cloud band orientation on Jupiter, and the generation of magnetic fields in thermally driven dynamos. The continuous low-gravity environment of the orbiting space shuttle offers a unique opportunity to make laboratory studies of such large-scale thermally driven flows under the constraint imposed by rotation and sphericity. This is possible because polarization forces in a dielectric liquid, which are linearly dependent on fluid temperature, give rise to an effectively radial buoyancy force when a radial electrostatic field is imposed. The Geophysical Fluid Flow Cell (GFFC) is an implementation of this ideal in which fluid is contained between two rotating hemispheres that are differentially heated and stressed with a large a-c voltage. The experiment, to be flown on Spacelab III (currently set for launch April 29, 1985), will explore non-linear mode selection and high Rayleigh number turbulence in a rotating convecting spherical shell of liquid. Experiments will be carried out in a low driving parameter range where some limited numerical experimentation is currently feasible, as well as in a parameter range significantly beyond numerical computation for many years.
    Keywords: GEOPHYSICS
    Type: NASA. Marshall Space Flight Center NASA(MSFC FY-85 Atmospheric Processes Research Review; 3 p
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  • 7
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    The electron foreshock (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: ISEE particle and wave data are noted to furnish substantial support for the basic features of the velocity dispersed model at the foreshock boundary that was proposed by Filbert and Kellogg (1979). Among many remaining discrepancies between this model and observation, it is noted that unstable reduced velocity distributions have been discovered behind the thin boundary proposed by the model, and that these are at suprathermal energies lying far below those explainable in terms of an oscillating, two-stream instability. Although the long-theorized unstable beam of electrons has been found in the foreshock, there is still no ready explanation of the means by which it could have gotten there.
    Keywords: GEOPHYSICS
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  • 8
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    The relations between the linear and bilinear atmospheric tidal fields in geometric height and in log-pressure coordinates (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Theoretical models of planetary-atmosphere tidal fields are examined analytically, comparing models based on geometric-height coordinates with those employing log-pressure coordinates. The relationship between the linearized meteorological variables in the two systems is explored for classical tidal theory and its reduction to the Laplace tidal equation, and it is shown that identical horizontal and vertical equations are obtained. Also considered are the tidal zonal-mean bilinear flux convergences and their Eliassen-Palm formulations. Numerical results for problems involving the earth and Mars atmospheres are presented in graphs and discussed.
    Keywords: GEOPHYSICS
    Type: Pure and Applied Geophysics (ISSN 0033-4553); 123; 6, 19; 902-920
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  • 9
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    The form of Newtonian cooling in atmospheric tidal theory (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The analytical results of Zurek (1986) are applied to compare the vertical-structure equations obtained by Dickinson and Geller (1968) and Lindzen and McKenzie (1967) in solving the classical tidal equations for planetary atmospheres when Newtonian cooling (NC) is included as part of diabatic tidal forcing. The two diabatic forcings are found to be different when the basic state temperature varies with height, and it is recommended that a log-pressure NC formulation be used whenever temperature is made a function of pressure in the radiative-damping calculation. Scaling arguments are presented to show that the choice of NC formulation has significant effects only in cases where the radiative time constants are short (such as the thin CO2 atmosphere of Mars). Numerical computations for that case indicate a difference of 20 percent in amplitude and 15 deg in phase for the (probably meteorologically significant) 4.1-d wavenumber-one Rossby tidal mode.
    Keywords: GEOPHYSICS
    Type: Pure and Applied Geophysics (ISSN 0033-4553); 123; 6, 19; 921-929
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  • 10
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    SM-ND isotopic studies of proterozoic anorthosites Systematics and implications (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Sm-Nd isotopic studies of anorthosites can be used to provide information on their ages of crystallization and metamorphism, contamination history, and mantle sources. Proterozoic anorthosites in the Grenville and Nain Provinces of eastern North America crystallized between about 1100 and 1600 Ma, and some were metamorphosed at about 1000 Ma. Grenville Province anorthosite massifs were derived from depleted mantle. It is not clear whether massifs and related mafic intrusions throughout the Nain Province of Labrador were derived from enriched mantle, or were contaminated by early Archean (greater than 3500 Ma) silicic crustal materials, heretofore thought to be restricted to coastal Labrador.
    Keywords: GEOPHYSICS
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  • 11
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    The global response of stratospheric ozone to ultraviolet solar flux variations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The relation between rotational modulation of the ultraviolet solar irradiance and variations in atmospheric ozone has been investigated using Fourier transform harmonic analysis and cross-correlations. Ozone variations with the same period and phase as 13.5 day or 27-day solar flux variations occur at tropical and subtropical latitudes over a range of pressure levels centered about 3 mbar. The solar-forced oscillation is stronger in the summer hemisphere; as temperature-related variations would be stronger in winter. Changes in solar irradiance over the 11-year cycle can be estimated by scaling rotational modulation. Using this estimate and the ozone-sun relation obtained for rotational modulation yields solar cycle changes of 3.5 percent in 3 percent mixing ratio comparable to that predicted from halocarbons and 0.7 mbar in total ozone.
    Keywords: GEOPHYSICS
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  • 12
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    Ozone depletion during solar proton events in solar cycle 21 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Ozone profile data from the Solar Backscattered Ultraviolet Instrument on Nimbus 7 from 1979 to the present and clear cases of ozone destruction associated with five sudden proton events (SPEs) on June 7, 1979, August 21, 1979, October 13-14, 1981, July 13, 1982, and December 8, 1982 are found. During the SPE on July 13, 1982, the largest of this solar cycle, no depletion at all at 45 km is observed, but there is a 15 percent ozone depletion at 50 km increasing to 27 percent at 55 km, all at a solar zenith angle of 85 deg. A strong variation of the observed depletion with solar zenith angle is found, with maximum depletion occurring at the largest zenith angles (near 85 deg) decreasing to near zero for angles below about 70 deg. The observed depletion is short lived, disappearing within hours of the end of the SPE.
    Keywords: GEOPHYSICS
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  • 13
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    The ultraviolet cross-sections of ozone. I. The measurements. II - Results and temperature dependence (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Absorption cross-sections of ozone have been measured over the range 230 nm to 350 nm, and for temperatures 200 K to 300 K, with improved photometric accuracy and spectral resolution. These measurements are referred to the cross-section at the 253.65 nm mercury line by the Hearn value (1961), 1147 x 10 to the -20th/sq cm, and show an internal consistency of + or - 1 percent. Tables of ozone absorption cross-section in the ultraviolet have been prepared for intervals of 0.05 nm over the range 245 to 340 nm. at each wavelength entry in the table a set of coefficients has been derived that permits the cross-section to be computed as a function of temperature, between 200 K and 300 K, with an accuracy of 1 percent.
    Keywords: GEOPHYSICS
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  • 14
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    Ozone intercomparisons from the Balloon Intercomparison Campaign (1985)
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    Publication Date: 2011-08-19
    Description: Intercomparisons of remote and in-situ techniques used to measure stratospheric ozone are made using results obtained on the Balloon Intercomparison Campaign of 1982 and 1983. Two in-situ and four remote instruments participated. These included ECC ozonesondes, a UV absorption photometer, and microwave emission, IR emission, and absorption spectrometers. Differences are generally less than 15 percent, and are within the quoted error bars. Flights which involved different sets of instruments were made on four separate days, and results are intercompared in plots of ozone density versus altitude. A careful assessment of errors was made for each instrument, and a plot of absolute errors versus altitude is given.
    Keywords: GEOPHYSICS
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  • 15
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    High resolution infrared spectroscopic studies of atmospheric ozone and related trace constituents (1985)
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
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  • 16
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    Results from the Balloon Ozone Intercomparison Campaign (BOIC) (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In the Balloon Ozone Intercomparison Campaign (BOIC), several in situ UV absorption photometers, two solar UV absorption photometers, electrochemical sondes, and a mass spectrometer were intercompared in three flight missions. Concurrent data from Umkehr and satellite observations are also intercompared. The National Bureau of Standards provided a 'standard' ozone source for intercomparing the in situ instruments and ground pressure. Preliminary findings indicate that the standard deviation of the sensitivities among 17 instruments against the NBS reference was about 11 percent. These differences appear in flight at the lower levels and change at higher altitudes, indicating height-dependent errors. The difference among five in-situ UV photometers flown together ranged by plus or minus 8 percent during ascent to about 41 km. During float at 42 km, the difference nearly doubled. During descent, the difference decreased to about 4 percent, which is much closer to the expected accuracy of these instruments. Results from UV solar radiometers have been systematically higher than those from UV photometers by 15 to 20 percent - a very important disagreement that needs to be resolved.
    Keywords: GEOPHYSICS
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  • 17
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    Ozone-temperature relationships in the stratosphere (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Utilizing independent estimates of ozone and temperature fields from the SBUV (Nimbus 7) and NOAA operational satellites, respectively, for the period 1978-1981, the coefficient of variation between the two parameters is determined. This coefficient is defined as A = Delta-O3 x (T)/Delta T x (O3) wehre Delta is an incremental change in either temperature or ozone and the bracket is a mean state. In practice, A is determined on a daily basis by regression of ozone mixing ratio versus temperature around a latitude circle during the winter season and the bracket value is the daily zonal average. This has the advantage of keeping the solar zenith angle fixed for a daily value while allowing it to change during the season. This is done at 30, 10, 5, 2, and 1 mb from 20 deg to 60 deg latitude in both hemispheres. The results are summarized and compared with those determined from a one-dimensional photochemical model applied to different latitudes.
    Keywords: GEOPHYSICS
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  • 18
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    An evaluation of the performance of Umkehr stations by Solar Backscattered Ultraviolet (SBUV) experiment (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Until recently, Umkehr data taken by 20 Dobson stations around the world have been the principal source of information about the behavior of upper stratospheric ozone. Umkehr results are used also for detecting drifts in satellite instruments and for determining intersatellite biases. However, a systematic evaluation of the quality of Umkehr data taken by the various stations has been lacking. Five years of ozone profile data from the Solar Backscattered Ultraviolet (SBUV) have been used to examine and intercompare the quality of Umkehr stations, and to assess the degradation of their performance after the El Chichon volcano eruption in southern Mexico. In contrast to Umkehr, the SBUV ozone measurments in layers 7 through 9 (1-8 mb) were unaffected by the massive amounts of dust and gases ejected by El Chichon.
    Keywords: GEOPHYSICS
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  • 19
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    Intercomparison of satellite ozone profile measurements (1985)
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    Publication Date: 2011-08-19
    Description: Ozone profile data are intercompared with those from the LIMS and SBUV flown on Nimbus 7, SAGE flown on Atmospheric Explorer Mission 2, and the Ultraviolet and Infrared Spectrometers flown on the SME. Ozone data were derived from the measurements with independently derived processing algorithms. The data cover different time periods and have different spatial and temporal resolutions. The similarities and differences between the individual data sets are determined with effort focused on directly comparing the spacecraft data sets in the form of individual profiles, zonal mean profiles and global analyses. Comparisons with ground data from balloons and Umkehr stations are made.
    Keywords: GEOPHYSICS
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  • 20
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    Standard profiles of ozone from ground to 60 km obtained by combining satellite and ground based measurements (1985)
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    Publication Date: 2011-08-19
    Description: A study is reported based on four years of SBUV data and five years of published ozonesonde data. The Solar Backscatter Ultraviolet Experiment (SBUV), has been operating continuously since November 1978, providing some 1000 profiles per day. The data are of excellent quality from about 50 km down to the tropopause. By combining the satellite-derived data with ozonesonde data, a data base of standard ozone profiles and variance/covariance matrices has been developed, defining the observed variation of the atmospheric ozone around the mean profiles. Highlights of the data base are presented along with parameters of an analytical fit that describes the essential features of the data set. Although the data base was created specifically for use as a priori profiles for SBUV and Umkehr retrievals, it should be useful in other remote sensing applications and in modeling the UV radiation fields in the stratosphere. Another suggested application is in estimating ozone above the peak altitude of the ozone balloons.
    Keywords: GEOPHYSICS
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  • 21
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    The observation of atmospheric structure with TOMS and some potential advancements (1985)
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    Publication Date: 2011-08-19
    Description: An overview is given of the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) which was designed to observe the spatial characteristics of total ozone that were not resolved by the nadir-viewing Nimbus BUV and SBUV instruments. At the wavelengths suitable for total ozone measurements, the radiance is large enough that the entire daytime atmosphere could be surveyed with about 50-km resolution from a polar orbiting satellite. The resulting high spatial resolution TOMS ozone images are found to reflect the internal dynamic structure of the lower atmosphere. Features which can be identified and tracked include: planetary wave scale troughs and ridges, mesoscale cutoff lows and rapidly moving troughs, jet stream confluence and difluence areas, hurricanes, and polar night lows. These features control the ozone above any given location and account for nearly all the variance in the total ozone. The instrument has been used to track the volcanic eruption clouds from El Chichon, Mount St. Helens, Alaid, and smaller eruptions such as Galunggung. It would be feasible to use a similar instrument on a geostationary platform to obtain half-hourly maps. Determination of the vertical ozone distribution in the lower stratosphere using Radon transform principles would be of importance in measuring jet stream folds and the related troposphere-stratosphere exchange.
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  • 22
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    Measurements of atmospheric nitric oxide from Nimbus 7 SBUV ultraviolet spectral scan data (1985)
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    Publication Date: 2011-08-19
    Description: Results are given of SBUV (solar backscattered ultraviolet instrument) measurements from Nimbus 7, when - one day per month - it is operated in a spectral scan mode, scanning from 160 nm to 400 nm in 0.2-nm steps. By measuring the intensity of a series of nitric oxide (NO) gamma band fluorescence features in this wavelength range, it has been possible to estimate the amount of NO in the upper stratosphere and mesosphere. The background of atmospherically scattered sunlight normally masks the much weaker NO gamma band emission, but these emission features are discriminated by subtracting a synthetic spectrum calculated for a model atmosphere that includes only Rayleigh scattering and absorption by ozone and oxygen. The resulting difference plot clearly reveals features resulting from processes not included in the simple model, such as NO gamma band emission. Nitric oxide is inferred by measuring the absolute intensity of various bands relative to the adjacent background and relating this intensity to total NO above an altitude determined by the backscattering contribution function for that band. NO observations near the solstice and at various latitudes are reported.
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  • 23
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    Evidence for a thermospheric source of stratospheric NOx (1985)
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    Publication Date: 2011-08-19
    Description: Analyses of a three-year time series of rocket ozone measurements at Wallops Island, VA, a set of rocket ozone soundings across the Southern Hemisphere, and rocket soundings at Fort Churchill, Manitoba are reported. Evidence is obtained that the NOx budget is not simply explained by oxidation of biospheric nitrous oxide. I 1-D time-dependent photochemical model is used to compute the amount of NO2 required to maintain odd oxygen in a steady state after accounting for Chapman, odd hydrogen, and odd chlorine reactions. At Wallops Island, a mid-latitude station, the inferred seasonal variation of NOx is small with the fall and winter mixing ratios about 20 percent greater than the spring and summer values. The soundings at Fort Churchill require about the same NOx amount as at Wallops Island in the spring and summer months but more than twice this amount in late fall and winter. Results indicate that the nitrous oxide source of NOx is supplemented by a polar source during the fall and winter months. This is consistent with the descent of thermospheric air with its high nitric oxide content during the period of strong cooling in the polar night.
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  • 24
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    Nitric oxide profile from 7 to 32 km (1985)
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    Publication Date: 2011-08-19
    Description: An analysis is given of some results of the LIMS experiment, launched on the Nimbus 7 satellite on October 24, 1978 for the purpose of sounding the middle atmosphere composition and structure. One of the LIMS channels was centered spectrally in the 6 micron region to measure vertical profiles and the global distribution of NO2 mixing ratio. The data reveal that NO2 is highly variable with altitude, latitude, longitude and time. Steep latitudinal gradients are observed in high latitude winter ('the NO2 cliff') when a wave number one pattern exists in the geopotential height field. The daytime gradient under these conditions is less than that for the night. The summer hemisphere column amount is considerably greater (by a factor of about 2) than in the winter hemisphere. The largest mixing ratios occur at 4 mb at night (about 20 ppbv) and 9 mb in the day (about 7 ppbv) and the latitude region of the peak mixing ratio is skewed toward the Southern Hemisphere. The mixing ratio variability is greater at night (by a factor of about 2 to 3) than in the day and there are significant long-term changes revealed by mixing ratio time series analyses on a pressure vs time grid.
    Keywords: GEOPHYSICS
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  • 25
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    Global lower mesospheric water vapor revealed by LIMS observations (1985)
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    Publication Date: 2011-08-19
    Description: The Limb Infrared Monitor of the Stratospheric water vapor channel data analysis has been extended from the 1. mb level (about 48 km) to the .3 mb level (about 60 km) through a radiance averaging procedure and better understanding of systematic errors. The data show H2O mixing ratio peaks near the .5 mb level varying from 4 to 7 ppmv with latitude and season. Above this level the mixing ratio drops off quickly with altitude, but, due to experimental uncertainties, at an uncertain rate. The stratospheric results are virtually the same as determined from the archived LIMS results with a tropical hygropause and enhanced H2O concentration in the lower levels at high winter latitudes.
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  • 26
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    LIMS data - Inferred stratospheric distribution of NOx and HOx trace constituents and the calculated odd nitrogen budget (1985)
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    Publication Date: 2011-08-19
    Description: LIMS, SAMS, SBUV and in-situ data have been used to infer species not measured but which are of photochemical interest, e.g., O(3P), O(1D), NO, N2O5, OH, HO2, ClO and HCl. (LIMS = limb infrared monitor of the stratosphere; SAMS = stratospheric and mesospheric sounder; and SBUV = solar backscattered ultraviolet instrument.) Production and loss of odd nitrogen have been calculated and estimates have been made of the odd nitrogen transport due to adiabatically driven circulation derived from LIMS data. Data used from LIMS include O3, NO2, HNO3, H2O and T. CH4 and N2O were taken from SAMS and the UV solar flux from the SBUV instrument. Species were inferred for periods in October, December, March and May. Results for December are discussed. Results indicate: (1) maximum stratospheric odd nitrogen levels of 25 ppbv; (2) evidence of odd nitrogen transport from the mesosphere appearing at 25 km in the wintertime polar latitudes; (3) the polar night build-up of high levels of N2O5 beginning after the autumnal equinox; and (4) the possibility of large downward fluxes of odd nitrogen into the troposphere during the winter at latitudes poleward of 60 degrees.
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  • 27
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    A study of the ozone photochemistry in the upper stratosphere using LIMS data (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: LIMS data at vernal equinox conditions are used to study the photochemistry of the upper stratosphere. The results indicate, and it has been recently reported, that with the use of recommended reaction rates, current models underestimate ozone mixing ratio by 20-40 percent. For ozone, good agreement with data is realized with the modification of six key reaction rates within the published limits of uncertainty. These modifications also yield better agreement with data for daytime NO2. Model results for other parameters such as the ratio HNO3/NO2, OH mixing ratio, and the temperature sensitivity of O3 are compared with data.
    Keywords: GEOPHYSICS
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  • 28
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    Electron density in the equatorial topside (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Ionospheric electron content studies have revealed severe discrepancies between Faraday measurements and model predictions at low latitudes. In this investigation, satellite data of AE-C and Aeros and incoherent scatter data from Jicamarca, Peru and Arecibo, Puerto Rico are used to examine the latitudinal and diurnal extent of this disagreement. It is found that in the modified dip range -30 deg to +30 deg the present IRI relative layer shape underestimates the thickness of the topside electron density during both, day and night. The Bent model which was used as a source for the IRI description performs somewhat better in this critical dip range, though it does not reach the observed values. Also it does not show the observed diurnal variation. A correction to the IRI formula is proposed that guarantees better agreement with the satellite and incoherent scatter data.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 10, 1; 15-19
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  • 29
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    Implementation of the new electron temperature model in IRI (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Since the first edition of IRI in 1978, considerable efforts have been directed towards an improved and refined electron temperature description. Finally, a new empirical model was presented at the COSPAR meeting at Graz, Austria, in 1984 (Bilitza et al.). Based mainly on satellite data it highlights a more detailed diurnal, seasonal, and altitudinal variation. The implementation of this model into the IRI framework is described. A first comparison with incoherent scatter measurements indicates the improved diurnal and seasonal performance of the model.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 10, 1
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  • 30
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    Comparison of measured and predicted F2 peak altitude (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Different models for the F2 peak altitude hmF2 are compared with mean values determined from incoherent scatter measurements of the radar stations Jicamarca, Peru and Arecibo, Puerto Rico at all local times. The investigation shows that the daytime hmF2 is fairly well represented by the most recent models, whereas at nighttime, higher peak altitudes are measured rather than predicted by either model. The observed diurnal structure is slightly misinterpreted by the models above Jicamarca and is strongly disagreeing above Arecibo.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 10, 1
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  • 31
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    Recent research on magnetospheric wave-particle interactions (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Highlights of recent Stanford University VLF research in the Antarctic include new observations of wave-induced particle precipitation and controlled experiments on nonlinear wave growth phenomena. Higher-than-expected levels of burst precipitation have been discovered inside the plasmasphere, near L = 2, using subionospheric signal perturbations called 'Trimpi events'. Studies of burst precipitation have been extended to the region poleward of the plasmapause using the Siple transmitter signal as a waveguide probe. Experiments on the 'coherent wave instability', using the amplitude and frequency modulation capability of the new Siple transmitter, have produced exciting new results. Examples are: (1) better definition of the power threshold for the stimulation of temporal wave growth, (2) generation of strong sidebands by unamplified 'beat' waves and (3) generation of chorus-like elements within a band of simulated hiss. Using a new digital processing technique developed at Stanford, new features of the phase behavior of growing waves have been found. Opportunities for extending these experiments are discussed.
    Keywords: GEOPHYSICS
    Type: National Institute of Polar Research, Memoirs, Special Issue (ISSN 0386-0744); 38, D; 83-98
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  • 32
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    Microwave limb sounder for stratospheric measurements (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The balloon-borne Microwave Limb Sounder (BMLS) measures atmospheric thermal emission from millimeter wavelength spectral lines to determine vertical profiles of stratospheric species. The instrument flown to data operates at 205 BHz to measure ClO, O3, and H2O2. A 63 GHz radiometer is added to test the technique for determining tangent point pressure from the MLS experiment on the Upper Atmosphere Research Satellite (UARS). Many additional species is also measured by the BLMS. A radiometer at 270 GHz would provide measurements of HO2, NO2, HNO3, N2O, 16O18O16O, and HCN. With this addition the BMLS can test the current theory of O3 heavy ozone photochemical balance in the upper stratosphere.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions Middle Atmosphere Program. Handbook for MAP, Volume 15; p 90-123
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  • 33
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    Free radicals in the stratosphere - A new observational technique (1985)
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    Publication Date: 2011-08-19
    Description: A new approach to in situ observations of trace reactive species in the stratosphere is described. A balloon-borne system, floating 40 kilometers above the earth's surface, successfully lowered and then retracted a cluster of instruments a distance of 12 kilometers on a filament of Kevlar. This instrument cluster is capable of detecting gas-phase free radicals at the part-per-trillion level. The suspended instrument array has excellent stability and has been used to measured atomic oxygen concentrations in the stratosphere.
    Keywords: GEOPHYSICS
    Type: Science (ISSN 0036-8075); 228; 1309-131
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  • 34
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    Aircraft measurements of ammonia and nitric acid in the lower troposphere (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The first simultaneous measurements of ammonia and nitric acid in the troposphere have been made from an aircraft using a tungsten oxide denuder system. Vertical profiles of NH3 and HNO3 taken over coastal Virginia and Maryland in March and September, 1983, at altitudes from 150 m to 3000 m, show mixing ratios that decrease with altitude. Ammonia profiles show substantial seasonal variation, while nitric acid profiles do not. Using the measured profiles and a one-dimensional photochemical model, lifetimes due to heterogeneous loss of one day for HNO3 and ten days for NH3 are calculated. In contrast, NH3 profiles up to 5300 m over the North Atlantic Ocean during August 1982 show mixing ratios that increase slightly with altitude. These data represent the first ammonia profiles measured over the ocean. It is suggested that the increase in NH3 with altitude is a result of an ammonia-rich continental air mass advected over the ocean, followed by the dissolution of NH3 in the marine boundary layer on water-covered sea salt particles.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 401-404
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  • 35
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    Auroral zone effects on hydrogen geocorona structure and variability (1985)
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    Publication Date: 2011-08-19
    Description: The effect of diurnal and magnetospheric modulations on the structure of the hydrogen geocorona is analyzed on the basis of recent observations. Particular attention is given to the enhancement of neutral escape by plasma effects, including the recently observed phenomenon of low-altitude ion acceleration. It is found that, while significant fluxes of neutral H should be produced by transverse ion acceleration in the auroral zone, the process is probably insufficient to account for the observed polar depletion of hydrogen atoms. Analysis of recent exospheric temperature measurements from the Dynamics Explorer-2 satellite suggest that neutral heating in and near the high latitude cusp may be the major contributor to depleted atomic hydrogen densities at high latitudes. Altitude profiles of the production rates for escaping neutral hydrogen atoms during periods of maximum, minimum, and typical solar activity are provided.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 33; 499-505
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  • 36
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    Magnetotail energy storage and release during the CDAW 6 substorm analysis intervals (1985)
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    Publication Date: 2011-08-19
    Description: The concept of the Coordinated Data Analysis Workshop (CDAW) grew out of the International Magnetospheric Study (IMS) program. According to this concept, data are to be pooled from a wide variety of spacecraft and ground-based sources for limited time intervals. These data are to provide the basis for the performance of very detailed correlative analyses, usually with fairly limited physical problems in mind. However, in the case of the CDAW 6 truly global goals are involved. The primary goal is to trace the flow of energy from the solar wind through the magnetosphere to its ultimate dissipation by substorm processes. The present investigation has the specific goal to examine the evidence for the storage of solar wind energy in the magnetotail prior to substorm expansion phase onsets. Of particular interest is the determination, in individual substorm cases, of the time delays between the loading of energy into the magnetospheric system and the subsequent unloading of this energy.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 1205-121
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  • 37
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    Heat balance of the ionosphere - Implications for the International Reference Ionosphere (1985)
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    Publication Date: 2011-08-19
    Description: Theoretical considerations can be helpful tools in modeling ionospheric parameters in regions and for times where not enough experimental data are available. This study asks whether results of heat balance calculations should be introduced to supplement the data base for the International Reference Ionosphere. The present status of the theoretical understanding is discussed and the influence of the following unresolved or neglected times are examined: (1) electron heating rate, (2) electron cooling by fine structure excitation of atomic oxygen, and (3) height-dependent Coulomb Logarithm. The ambiguity introduced by these terms leads to up to 30 percent uncertainty in the electron temperature of the lower ionosphere. The electron temperature in the upper ionosphere is largely determined by heat conduction from above and depends critically on the conditions assumed at the boundary between ionosphere and plasmasphere.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 10, 1
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  • 38
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    Earth orientation from lunar laser ranging and an error analysis of polar motion services (1985)
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    Publication Date: 2011-08-19
    Description: Lunar laser ranging (LLR) data are obtained on the basis of the timing of laser pulses travelling from observatories on earth to retroreflectors placed on the moon's surface during the Apollo program. The modeling and analysis of the LLR data can provide valuable insights into earth's dynamics. The feasibility to model accurately the lunar orbit over the full 13-year observation span makes it possible to conduct relatively long-term studies of variations in the earth's rotation. A description is provided of general analysis techniques, and the calculation of universal time (UT1) from LLR is discussed. Attention is also given to a summary of intercomparisons with different techniques, polar motion results and intercomparisons, and a polar motion error analysis.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 9353-936
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  • 39
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    Observing tectonic plate motions and deformations from satellite laser ranging (1985)
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    Publication Date: 2011-08-19
    Description: The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 9249-926
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  • 40
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    Analysis of ozone data (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: NASA, Washington Upper Atmosphere Res. Program; p 193-195
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  • 41
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    Molecular properties and reaction rates (1985)
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: NASA, Washington Upper Atmosphere Res. Program; p 173-174
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  • 42
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    Comparison of mesospheric ozone measurements using the LRIR and UVMCS satellite instruments (1985)
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    Publication Date: 2011-08-19
    Description: A comparison between mesospheric ozone profiles determined by two radically different satellite-borne instruments is presented for the period of July to November, 1975. The Limb Radiance Inversion Radiometer measured 9.6-micron O3 emission, while the Ultraviolet Multiple Channel Spectrometer measured the atmospheric attenuation of solar ultraviolet radiation during passage of the OSO-8 satellite across the terminator. Only nine near coincident measurements were found. The individual instruments have estimated precision errors of + or - 10 to 15 percent. Agreement between ozone values as measured by the two techniques for specific cases varies between 10 and 20 percent. The statistical correlation is positive and significant at all altitudes where both instruments had reasonable signal-to-noise ratio. A maximum correlation of 0.76 occurred at 0.3 mb (about 59 km).
    Keywords: GEOPHYSICS
    Type: Annales Geophysicae (ISSN 0755-0685); 3; 439-443
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  • 43
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    Modelling of ionospheric temperature profiles (1985)
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    Publication Date: 2011-08-19
    Description: Ionosphere electron temperature data gathered by the AE-C, AEROS, Isis-1 and -2 spacecraft are employed to define linear models for the average conditions. Account is taken of evidence for seasonal, altitudinal, solar activity and density-temperature effects. Notably, use is made of the high negative correlations between the electron temperature and density, thereby allowing either to be calculated if data are available on the density.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 7, 19
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  • 44
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    Proposed ozone reference models for the middle atmosphere (1985)
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    Publication Date: 2011-08-19
    Description: Since the publication of the last COSPAR International Reference Atmosphere (CIRA 72), large amounts of ozone data acquired from satellites have become available in addition to increasing quantities of rocketsonde, balloonsonde, Dobson, M83, and Umkehr measurements. From the available archived satellite data, models are developed for the new CIRA using 5 satellite experiments (Nimbus 7 SBUV and LIMS, AEM-2 SAGE, and SME IR and UVS) of the monthly latitudinal and altitudinal variations in the ozone mixing ratio in the middle atmosphere. Standard deviations and interannual variations are also quantified. The satellite models are shown to agree well with a previous reference model based on rocket and balloon measurements.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 7, 19
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  • 45
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    Evidence for ion heat flux in the light ion polar wind (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Cold flowing hydrogen and helium ions have been observed using the retarding ion mass spectrometer on board the Dynamics Explorer 1 spacecraft in the dayside magnetosphere at subauroral latitudes. The ions show a marked flux asymmetry with respect to the relative wind direction. The observed data are fitted by a model of drifting Maxwellian distributions perturbed by a first order-Spritzer-Haerm heat flux distribution function. It is shown that both ion species are supersonic just equatorward of the auroral zone at L = 14, and the shape of asymmetry and direction of the asymmetry are consistent with the presence of an upward heat flux. At L = 6, both species evolve smoothly into warmer subsonic upward flows with downward heat fluxes. In the case of subsonic flows the downward heat flux implies a significant heat source at higher altitudes. Spin curves of the spectrometer count rate versus the spin phase angle are provided.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 8552-855
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  • 46
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    Gravity anomalies and flexure of the Brazilian Shield beneath the Bolivian Andes (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Earth and Planetary Science Letters (ISSN 0012-821X); 75; 1, Se; 81-92
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  • 47
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    Associated middle to late Jurassic volcanism and extension in southern South America (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Tectonophysics (ISSN 0040-1951); 116; 223-253
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  • 48
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    Fine structure and dynamics of the Harang discontinuity - An event study (1985)
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    Publication Date: 2011-08-19
    Description: Two rockets were launched simultaneously from the Andoya Rocket Range in northern Norway into and through a Harang discontinuity region during a small isolated substorm. Each was equipped with an array of instruments for monitoring ionospheric electric fields and auroral particles. Different sized rockets allowed both to traverse a range of 300 km while introducing altitude separations of up to 440 km, and separations between the feet of the magnetic field lines intersecting the payloads of up to 100 km. The data sets, coupled with multi-station ground-based observations, provide information on the structure and dynamics of the Harang discontinuity region. Two boundaries were encountered. The first electric field reversal was observed simultaneously by both payloads in a region of weak precipitation, while the second reversal was associated with an intense auroral band. Since an unambiguous interpretation of these data is not possible, two alternative scenarios are presented. In one the discontinuity becomes realigned during the flight following a decay in the activity. The second involves a triple cell convection system, possibly the result of an eddy in the flow.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics (ISSN 0021-9169); 47; 693-705
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  • 49
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    On the excitation of the earth's polar motion (1985)
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    Publication Date: 2011-08-19
    Description: Reference is made to recent studies by Barnes et al. (1983) and Hide (1984) in which a conclusion is made that atmospheric excitation alone is sufficient to account for the earth's polar motion over the studied periods. It is then shown through a physical 'thought' experiment and a numerical simulation that this conclusion is unjustified since the information about the Chandler wobble presented in these papers is insufficient. Whether the conclusion is true or not, however, remains an open question.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 526-529
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  • 50
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    Constraints on Pacific plate kinematics and dynamics with global positioning system measurements (1985)
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    Publication Date: 2011-08-19
    Description: A measurement program designed to investigate kinematic and dynamic aspects of plate tectonics in the Pacific region by means of satellite observations is proposed. Accuracy studies are summarized showing that for short baselines (less than 100 km), the measuring accuracy of global positioning system (GPS) receivers can be in the centimeter range. For longer baselines, uncertainty in the orbital ephemerides of the GPS satellites could be a major source of error. Simultaneous observations at widely (about 300 km) separated fiducial stations over the Pacific region, should permit an accuracy in the centimeter range for baselines of up to several thousand kilometers. The optimum performance level is based on the assumption of that fiducial baselines are known a priori to the centimeter range. An example fiducial network for a GPS study of the South Pacific region is described.
    Keywords: GEOPHYSICS
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-23; 491-501
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  • 51
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    Utilization of mobile VLBI for geodetic measurements (1985)
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    Publication Date: 2011-08-19
    Description: Three mobile very long base interferometry (VLBI) systems were fabricated for the NASA Crustal Dynamics Project. These systems include the 9-meter-diameter MV-3 telescope. Since 1980, mobile systems operated in conjunction with several fixed base stations in the western United States as part of a geodetic survey program to determine relative motions and regional strain fields near the tectonic plate boundaries in California and Alaska. A description is given of the three mobile systems and the environment in which they must function. The inherent accuracy of mobile VLBI measurements is assessed, based on a consideration of major sources of error. Some recent results are presented which serve to illustrate various aspects of the error model and are of geodetic interest as they span the broad region surrounding the surface trace of the San Andreas Fault. These results indicate that baseline measurements utilizing the current mobile VLBI systems attained an accuracy of 2 cm or better in the horizontal plane. It is likely that crustal motions will be detected within the next few years, provided they are presently occurring at the geological rates.
    Keywords: GEOPHYSICS
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-23; 426-437
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  • 52
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    Earth rotation and polar motion - Measurements and implications (1985)
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    Publication Date: 2011-08-19
    Description: Several methods used to measure earth rotation and polar motion are discussed. The development of techniques for combining smoothing, and intercomparing geodetic measurements is described. Emphasis is given to measurements obtained since 1980 using VLBI, lunar laser ranging (LLR) and satellite laser ranging (SLR) techniques. The calculation of atmospheric angular momentum (AAM) excitation functions is outlined, and a comparison of AAM excitation functions with variations in the length of day (LOD) and polar motion data is presented. The geophysical implications of geodetic measurements are addressed.
    Keywords: GEOPHYSICS
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-23; 373-384
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  • 53
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    The role of nonlocalities in magnetosphere-ionosphere coupling processes (1985)
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    Publication Date: 2011-08-19
    Description: Microinstabilities are believed to play a crucial role in the physics of magnetosphere-ionosphere coupling. The current driven ion cyclotron instability is a very important microinstability in this respect. A nonlocal formalism is given for studying the ion cyclotron instability in a more realistic magnetospheric environment than is available in the widely used local theory. This formalism includes the magnetic shear produced self-consistently by the field aligned currents and the finite extent of such currents. Significant departures from the local theory are noted.
    Keywords: GEOPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 4, 19; 19-22
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  • 54
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    The source of midlatitude metallic ions at F-region altitudes (1985)
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    Publication Date: 2011-08-19
    Description: The results of a survey of metallic ions detected by the Bennett Ion Mass Spectrometer flown on the Atmospheric Explorer satellites are presented and discussed. The nighttime distribution of these ions observed in the F-region at middle latitudes can be accounted for by the presence of fast upward Pederson ion drifts that are produced by intense poleward-directed electric fields with magnitudes typical of those defining subauroral drift events. Such fields, which arise in the vicinity of the main electron density trough at night, result in the rapid movement of long-lived meteoric ions upwards out of their source region into the F-region. Neutral wind drag by the equatorially-directed nightside neutral wind component can lift the ions higher along the field lines until the downward drag of major ion diffusion forces them to layer under F-max.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 33; 807-815
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  • 55
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    Particles upstream of the pre-dawn bow shock - ISEE-3 observations (1985)
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    Publication Date: 2011-08-19
    Description: The first observations of energetic ions (equal to or greater than 30 keV) in the region upstream of the pre-dawn bow shock (X between 0 and -60 Re inclusively) are presented. The intensity in this region is controlled by the direction of the interplanetary magnetic field (IMF) and is maximized when the IMF is around the spiral direction. The particle distributions are highly anisotropic with the anisotropy directed perpendicular to the magnetic field. In the E x B frame this perpendicular anisotropy is conserved and it is argued that the distribution is pancake-like. This indicates that the energetic particles in the pre-dawn upstream region have their origin in the near-earth upstream region, from where they are convected by the solar wind perpendicular to the magnetic field. It is therefore concluded that acceleration occurs mainly near the nose of the bow shock, and particle acceleration at the distant bow shock is weak.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 373-376
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  • 56
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    A spectral analysis of the earth's angular momentum budget (1985)
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    Publication Date: 2011-08-19
    Description: The exchange of angular momentum between the solid earth and the atmosphere from January 1976 through March 1982 is investigated using estimates of the earth's rotation from optical astrometry and lunar laser ranging and meteorological estimates of the atmospheric angular momentum M(atm). The physics of the earth's angular momentum budget is described, and earth rotation measurements are related to changes in the angular momentum of the fluid parts of the earth. The availability and reliability of earth rotation and M(atm) data are reported, and the possibility of estimating the exchange of angular momentum with the oceans and with the core is examined. Estimates of the power spectrum, cospectral coherence, and linear transfer functions and an analysis of the unmodeled part of the angular momentum budget are presented and discussed. The amplitude and phase of the semiannual, monthly, and fortnightly tidal variations in the length of day are estimated after removing observed atmospheric excitation.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 5385-540
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    Latitude survey of aerosol optical thickness of the El Chichon eruption cloud in May 1983 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The results of measurements of the latitudinal distribution of the El Chichon eruption cloud in May 1983 for the latitude range between 71 deg N and 56 deg S are presented. Aerosol optical thicknesses are calculated from solar spectral extinction measurements made with a sunphotometer on board the NASA Convair 990 aircraft. It is shown that the thicknesses vary in the range between 0.12 and 0.01, that a maximum of about 0.12 is found at middle latitudes, and that distinct minima of 0.01-0.02 are observed at 25-deg latitude in both hemispheres. The median radius of particles is found to be between 0.16 micron and 0.18 micron in the northern hemisphere and between 0.11 micron and 0.15 micron in the southern hemisphere. Rough estimates of aerosol mass indicate that about 1.5 megatonnes of aerosol still persisted in the stratosphere between the equator and 25-deg N one year after the eruption.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 255-258
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  • 58
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    A simulation of high latitude F-layer instabilities in the presence of magnetosphere-ionosphere coupling (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A simulation of inertial high-latitude ionospheric interchange instabilities, including magnetospheric coupling effects is presented. It is shown that the primary magnetosphere-ionosphere coupling effect is to incorporate the inertia of the magnetospheric plasma in the analysis. The following conclusions are drawn from the simulation: (1) magnetospheric coupling effects reduce the growth rate of the interchange instability, (2) striations produced by the inertial interchange instability develop in a different manner than in the noninertial regime, and (3) striations produced in the inertial regime are more isotropic and spread out, resulting in irregularities oriented perpendicular to those produced in the noninertial case.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 283-286
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  • 59
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    Estimates of the stratospheric distribution of odd nitrogen from the LIMS data (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Reasonable lower-limit estimates of the latitude-altitude distribution of stratospheric NO(x) for December 1978 and March 1979 are presented. The lower-limit estimates are based on nighttime measurements of NO2 and HNO3 taken by the LIMS instrument aboard the NIMBUS 7 satellite. It is shown that the estimates do not depend upon model calculations or a priori knowledge of the nature of the stratospheric photochemical system. The results indicate that the measured sum of nighttime NO2 nd HNO3 is as high as 22.5 + or - ppbv and that atmospheric NO(x) levels may be as high as 26 + or - 4.5 ppbv at 37 km, which is larger than most calculated NO(x) levels.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 259-262
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  • 60
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    The impact of polar stratospheric clouds on the heating rates of the winter polar stratosphere (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The perturbation affecting IR radiative heating rates of the lower stratosphere that are prompted by the occurrence of polar stratospheric clouds (PSCs) during the Arctic and Antarctic winter are presently calculated by means of a multispectral radiative transfer code that allows for scattering, absorption, and thermal emission by particles and gases. Attention is given to perturbations arising from both the particulate opacity of the PSCs and the decrease of H2O vapor accompanying their formation. For plausible values of model parameters, the former, direct effect is always one of increased radiative cooling, while the indirect effect is always one of decreased cooling.
    Keywords: GEOPHYSICS
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 42; 245-262
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  • 61
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    Influence of meteorological conditions on aerosol vertical distribution and composition off the northeast American coastline (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The size distribution and composition of lower tropospheric aerosols were measured off the northeast American coastline under clear air and disturbed meteorological conditions. Under the clear air conditions observed on 5 August 1982, with air flow from west to east, sulfate-rich stratified layers are the dominant feature of aerosol distribution in the lowest 3000 m of the troposphere. The encroachment of a warm frontal system over the study area on 9 August 1982 resulted in dramatic changes in aerosol distribution and composition prior to any precipitation, probably due to increased vertical mixing and dilution of pollutant aerosols. Chloride becomes the dominant water soluble anion in the lower 3000 m, primarily due to a several fold decrease in sulfate. Although these results are limited to only two sets of measurements, the data indicate the variability which can occur in the tropospheric vertical aerosol distributions at remote locations. A knowledge of the structure and stability of these stratified layers is of particular importance to studies of the ocean-troposphere chemistry problem.
    Keywords: GEOPHYSICS
    Type: Atmospheric Environment (ISSN 0004-6981); 19; 423-428
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  • 62
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    Causes of increasing atmospheric methane - Depletion of hydroxyl radicals and the rise of emissions (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A combination of anthropogenic activities and a possible decline of global concentrations for the hydroxyl radicals that formerly removed methane from the atmosphere are cited as potential causes for the 1.3 percent/year rise of atmospheric methane levels. Calculations are presented which show that much of the methane increase over the last 200 years is probably to be divided among the two main sources in the proportions of 70 percent for anthropogenic generation and 30 percent for hydroxyl radical depletion. It is projected that in 20 years, average tropospheric concentrations of methane may be about 20 percent greater than 1980 levels. The current abundance of hydroxyl radicals may be 20 percent less than two centuries ago.
    Keywords: GEOPHYSICS
    Type: Atmospheric Environment (ISSN 0004-6981); 19; 397-407
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  • 63
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    Cusp altitudinal electron temperature gradient - Dynamics Explorer 2 implications for heating mechanisms (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Curtis et al. (1982) have shown that the levels of wave turbulence observed by Dynamics Explorer 2 (DE 2) are too low by several orders of magnitude to explain the high temperatures of the polar cusp ionosphere in terms of local deposition of energy. The low altitude plasma instrument (LAPI) showed high levels of superthermal electron fluxes. The present investigation has the objective to examine the arising questions more quantitatively by using the DE 2 electron temperature and superthermal electron flux measurements. It is shown that on the basis of DE 2 observations in the polar cusp, a consistent picture can be drawn regarding the ionospheric electron heating process. It is pointed out that the heating involves the generation of plasma waves by field-aligned electron beams of magnetosheath origin.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 4415-441
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  • 64
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    A new source of suprathermal O(+) ions near the dayside polar cap boundary (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A large number of data on suprathermal O(+) ions taken during the retarding ion mass spectrometer (RIMS) experiment aboard the DE 1 satellite are surveyed. Examples are found of low-energy, upflowing O(+) which are consistent with one or more of the proposed ionospheric escape mechanisms. These include transversely accelerated O(+) ions, indicating low-altitude transverse acceleration, and O(+) field-aligned flows which indicate low-altitude parallel acceleration by either ambipolar or current-driven electric fields. However, by far the most common pitch angle distribution of escaping O(+) is found to be a new type of O(+) flow event which provides evidence for both perpendicular and parallel ion acceleration below the satellite and is found exclusively in the lower latitudes of the dayside polar cap. All species of ions are observed to move upward during these events, with an upward heat flux.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 4099-411
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  • 65
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    Polar rain - Solar coronal electrons in the earth's magnetosphere (1985)
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    Publication Date: 2011-08-19
    Description: Low energy electron measurements collected by ISEE 1 reveal the frequent presence of field-aligned fluxes of few hundred eV electrons in the geomagnetic tail lobes. In the northern tail lobe these electrons are most prominent when the interplanetary magnetic field is directed away from the sun. This characteristic helps identify the electrons as polar rain electrons. By mapping the tail lobe velocity distribution function into the solar wind, previous suggestions that the polar rain is indeed of solar wind origin and is due to the access of electrons to the magnetotail lobe were confirmed. It was demonstrated that the more energetic component of the polar rain is composed of electrons from the solar wind strahl - a field-aligned component of the solar wind which is difficult to measure but which is thought to be caused by the collisionless transit of hundred eV electrons from the inner solar corona to 1 AU.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 4055-406
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  • 66
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    Predictability of the earth's polar motion (1985)
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    Publication Date: 2011-08-19
    Description: The results of a numerical experiment on the predictability of terrestrial polar motion using a Bureau International de l'Heure data set from 1967-83 are presented. A floating point predictor was defined by decomposing polar motion into secular motion and annual and Chandler wobbles. The secular term was linear and the others periodic, the former due to atmospheric mass transport and the latter to Eulerian nutation. A least squares estimator was employed with the data base to obtain constants for the model, which is given the name 'floating-point'. A fixed-period predictor was also devised and, in comparison with the floating point predictor in 6 yr estimates of the annual wobble period, failed after a given length of time. It is suggested that the failure is due to atmospheric motions.
    Keywords: GEOPHYSICS
    Type: Bulletin Geodesique (ISSN 0007-4632); 59; 1, 19; 81-93
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  • 67
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    The westward thermospheric jet-stream of the evening auroral oval (1985)
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    Publication Date: 2011-08-19
    Description: Ground-based and satellite measurements of the thermospheric wind in jet-streams during the evening auroral oval are analyzed, in order to study the geophysical mechanisms of thermospheric wind generation. Numerical simulations using a global, three-dimensional, time-dependent model of thermospheric dynamics were compared with the satellite data, and the results are discussed in detail. The wind distribution during the storm is shown in a series of color plates.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 33; 425-443
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  • 68
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    Measurements of the E region neutral wind field (1985)
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    Publication Date: 2011-08-19
    Description: The neutral E-region wind field was measured at Calgary, Canada (51 N, 114 N) during 75 nights in 1982. Observations of the Doppler shift of the 5577-A emission line of atomic oxygen using a Fabry-Perot interferometer were converted to horizontal wind vectors. From the analysis of the data, four categories of wind characteristics were identified. In order of increasing magnetic activity these categories are: (1) wind field mostly variable in space and time; (2) predominantly equatorward flow throughout the night, (3) predominantly poleward flow throughout the night and (4) north-westward flow before midnight and southward after midnight. The wind magnitude was also variable and on some disturbed days exceeded 200 m/s.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 33; 373-379
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  • 69
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    Finite field of view effects on inversion of limb thermal emission observations (1985)
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    Publication Date: 2011-08-19
    Description: It is pointed out that the technique of thermal emission spectroscopy provides an effective means for remote sounding of stratospheric temperature structure and constituent distributions. One procedure for measuring the stratospheric infrared spectrum involves the conduction of observations along ray paths tangent to the stratospheric limb. Thermal emission limb tangent observations have certain advantages compared to other types of observations. The techniques for determining temperature and trace gas distributions from limb thermal emission radiances are based on the assumption that the bulk of opacity lies near the tangent point. Ideally, the field of view (FOV) of the observing instrument should be very small. The effect of a finite FOV is to reduce the spatial resolution of the retrieved temperature and constituent profiles. The present investigation is concerned with the effects of the FOV on the inversion of infrared thermal emission measurements for balloon platforms. Attention is given to a convenient method for determining the weighting functions.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 20; 3903-390
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  • 70
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    Stratospheric H2O and HNO3 profiles derived from solar occultation measurements (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Compact two-channel radiometers for solar occultation experiments have been constructed in order to measure stratospheric trace gases. The instruments can be used as filter- or correlation-type radiometers, depending on the trace gas under investigation. Within the LIMS correlative measurement program, balloon flights were performed with a payload of up to four of these two-channel radiometers. From the filter-type measurements, profiles of the trace gases H2O and HNO3 are inferred for the height region between the tropopause and the balloon float level. The data evaluation also includes a comprehensive analysis of the error sources and their effect on the accuracy of the trace gas profiles. The derived H2O and HNO3 profiles are assessed against the observations of other authors and are discussed in the light of the trace gas distributions calcualted from photochemical models.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 20; 3831-384
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  • 71
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    Satellite observations of the nitric oxide dayglow Implications for the behavior of mesospheric and lower-thermospheric odd nitrogen (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The solar backscattered ultraviolet spectral radiometer on the Nimbus 7 satellite routinely measures fluorescence emissions from the nitric oxide (1, 4) gamma band that are imposed on the large Rayleigh-scattered signal in the wavelength range 255-256 nm. The gamma band feature, when isolated from the background radiance, provide information on the seasonal and latitudinal variations in the nitric oxide column abundance over the altitude region from 40 to 45 km upward through the thermosphere. At latitudes from 30 deg to 45 deg in the Northern Hemisphere the measurements show an annual cycle with maximum nitric oxide abundance in summer. The Southern Hemisphere pattern is qualitatively similar to this, although the amplitude of the seasonal variation is substantially smaller. The most prominent feature of the data base is a large maximum in nitric oxide emission that develops poleward of 45 deg latitude in both Hemispheres during late autumn and early winter. These maxima dissipate rapidly as spring approaches and are no longer evident in the data for Northern Hemisphere March and Southern Hemisphere September.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 20; 3821-383
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  • 72
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    Infrared measurements of atmospheric ethane (C2H6) from aircraft and ground-based solar absorption spectra in the 3000/cm region (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A number of prominent Q-branches of the nu-7 band of C2H6 have been identified near 3000/cm in aircraft and ground-based infrared solar absorption spectra. The aircraft spectra provide the column amount above 12 km at various altitudes. The column amount is strongly correlated with tropopause height and can be described by a constant mixing ratio of 0.46 ppbv in the upper troposphere and a mixing ratio scale height of 3.9 km above the tropopause. The ground-based spectra yield a column of 9.0 x 10 to the 15th molecules/sq cm above 2.1 km; combining these results implies a tropospheric mixing ratio of approximately 0.63 ppbv.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 199-202
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  • 73
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    Viscous remanent magnetization model for the Broken Ridge satellite magnetic anomaly (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An equivalent source model solution of the satellite magnetic field over Australia obtained by Mayhew et al. (1980) showed that the satellite anomalies could be related to geological features in Australia. When the processing and selection of the Magsat data over the Australian region had progressed to the point where interpretation procedures could be initiated, it was decided to start by attempting to model the Broken Ridge satellite anomaly, which represents one of the very few relatively isolated anomalies in the Magsat maps, with an unambiguous source region. Attention is given to details concerning the Broken Ridge satellite magnetic anomaly, the modeling method used, the Broken Ridge models, modeling results, and characteristics of magnetization.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2640-264
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  • 74
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    Magsat and POGO magnetic anomalies over the Lord Howe Rise Evidence against a simple continental crustal structure (1985)
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    Publication Date: 2011-08-19
    Description: Magsat average scalar and POGO reduced-to-pole magnetic anomaly data both show prominent positive signatures over the Lord Howe Rise. Although generally assumed to be continental in nature, the Lord Howe Rise cannot simply be submerged ordinary continental crust, which would produce a negative anomaly contrast with respect to the surrounding higher susceptibility oceanic crust. Three-dimensional modeling of the plateau, using the known crustal structure and assuming an induced origin for the satellite elevation anomaly, leads to a model in which the lowest crustal layer in an otherwise 'continental' crustal structure has an unusually high susceptibility in the range cgs 0.008-0.010 (SI 0.10-0.13). Replacement or alteration of the lowest layer by a high-susceptibility rock type may be related to the subsidence of the plateau.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2631-263
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  • 75
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    An estimation of continental crust magnetization and susceptibility from Magsat data for the conterminous United States (1985)
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    Publication Date: 2011-08-19
    Description: The Magsat-derived magnetic anomaly field over the United States was inverted to magnetization in a seismically determined variable-thickness lower crust. The results are quite similar to those obtained from a previous inversion of POGO data. The average magnetization is 3.45 + or - 1.0 A/m, which gives a bulk magnetic susceptibility of 8.7 + or - 2.4 x 10 to the -2nd (SI units) for the lower crustal layer consistent with a mafic composition. These values are also consistent with previous estimates of lower crustal magnetization from aeromagnetic data and with laboratory measurements of mafic rock susceptibilities.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2617-262
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  • 76
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    Crustal structure of the Churchill-Superior boundary zone between 80 and 98 deg W longitude from Magsat anomaly maps and stacked passes (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A modeling technique using spherical shell elements and equivalent dipole sources has been applied to Magsat signatures at the Churchill-Superior boundary in Manitoba, Ontario, and Ungava. A large satellite magnetic anomaly (12 nT amplitude) on POGO and Magsat maps near the Churchill-Superior boundary was found to be related to the Richmond Gulf aulacogen. The averaged crustal magnetization in the source region is 5.2 A/m. Stacking of the magnetic traces from Magsat passes reveals a magnetic signature (10 nT amplitude) at the Churchill-Superior boundary in an area studied between 80 deg W and 98 deg W. Modeling suggests a steplike thickening of the crust on the Churchill side of the boundary in a layer with a magnetization of 5 A/m. Signatures on aeromagnetic maps are also found in the source areas for both of these satellite anomalies.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2621-263
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  • 77
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    Comparison between the recent U.S. composite magnetic anomaly map and Magsat anomaly data (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present investigation is concerned with a comparison of Magsat data with a Composite Magnetic Anomaly Map (CMAM) of the conterminous U.S. reported by Zietz (1982). The investigation was initiated to test the validity of the satellite measurements, and to provide insights into error or problems in either data set. It is found that upward continuation of the digital CMAM data is not in qualitative agreement with the Magsat map. However, if a least squares fit polynomial surface is taken out prior to upward continuation, there is improved quantitative agreement between a residual CMAM and Magsat. Causes for the remaining differences between the residual, upward continued CMAM and the Magsat map are also considered.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2543-254
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  • 78
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    The near-earth magnetic field at 1980 determined from Magsat data (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Data from the Magsat spacecraft for November 1979 through April 1980 and from 91 magnetic observatories for 1978 through 1982 are used to derive a spherical harmonic model of the earth's main magnetic field and its secular variation. Constant coefficients are determined through degree and order 13 and secular variation coefficients through degree and order 10. The first degree external terms and corresponding induced internal terms are given as a function of Dst. Preliminary modeling using separate data sets at dawn and dusk local time showed that the dusk data contains a substantial field contribution from the equatorial electrojet current. The final data set is selected first from dawn data and then augmented by dusk data to achieve a good geographic data distribution for each of three time periods: (1) November/December, 1979; (2) January/February, 1980; (3) March/April, 1980. A correction for the effects of the equatorial electrojet is applied to the dusk data utilized. The solution included calculation of fixed biases, or anomalies, for the observation data.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2495-250
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    Introduction to the special issue - A perspective on Magsat results (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2441-244
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  • 80
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    Large-scale, near-field magnetic fields from external sources and the corresponding induced internal field (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Data from Magsat analyzed as a function of the Dst index to determine the first degree/order spherical harmonic description of the near-earth external field and its corresponding induced field. The analysis was done separately for data from dawn and dusk. The Magsat data was compared with POGO data. A local time variation of the external field persists even during very quiet magnetic conditions; both a diurnal and 8-hour period are present. A crude estimate of Sq current in the 45 deg geomagnetic latitude range is obtained for 1966 to 1970. The current strength, located in the ionosphere and induced in the earth, is typical of earlier determinations from surface data, although its maximum is displaced in local time from previous results.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2487-249
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  • 81
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    Infrared limb-darkening effects for the earth-atmosphere system (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: AIAA Journal (ISSN 0001-1452); 23; 405-409
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  • 82
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    Ram vehicle glow spectrum - Implication of NO2 recombination continuum (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An experiment was operated on several Space Shuttle missions to provide spatial and spectral distributions of a ram glow associated with the Orbiter. The most recent data featured resolved spectrum and imagery of the glow with spectroscopic resolution of 34 A FWHM between 4000 and 8000 A. The spectrum of the glow on the Shuttle tail pod could be clearly separated from spectrum of the reflected light from the Orbiter. Analysis and comparison have been performed which strongly suggest the emission originates from recombination continuum of NO2. Both fast recombination (high temperature) and the spectral dependence in lifetime can describe the spectral difference. If the recombined NO2 retains 25 percent of the kinetic energy of the ram OI, the thickness of the glow layer can be explained by the lifetime of NO2 (2B1) recombination emission.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 97-100
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  • 83
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    A new ozone standard - The vapor pressure of ozone at liquid argon temperatures (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The vapor pressure of ozone has been measured at liquid argon temperatures. At the normal boiling point of argon (-185.9 C) an ozone pressure of 0.0405 torr was obtained with an accuracy of + or - 1.5 percent. Increases and decreases in liquid argon temperatures raised and lowered the ozone vapor pressure, respectively. During the vapor pressure measurements the purity of ozone was monitored with a mass spectrometer. The proposed ozone standard will considerably improve the calibration of experiments for atmospheric research, the determination of absorption cross sections and other laboratory ozone studies.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 89-92
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  • 84
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    Solar-induced oscillations in the stratosphere - A myth or reality? (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Chandra (1984) has provided an assessment of the solar cycle ozone relationship based on seven years of Nimbus 4 BUV (backscattered ultraviolet) data. It was found that the globally averaged ozone in the upper stratosphere, when corrected for the changes in instrument sensitivity, decreased from 1970 to 1976 by 3-4 percent. This decrease is in accordance with the current estimates of solar UV variability over a solar cycle. The present investigation has the objective to determine if measured changes in ozone and temperature in the upper stratosphere on a time scale of a solar rotation are of solar origin, i.e., directly induced by changes in solar irradiance. The conducted study is based on the first two years (1970-1972) of ozone and temperature data obtained from the Nimbus 4 BUV and the Selective Chopper Radiometer (SCR) experiments. Attention is given to the response of the stratosphere to changes in solar activity associated with the 27-day solar rotation.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2331-233
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  • 85
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    An assessment of thermal, wind, and planetary wave changes in the middle and lower atmosphere due to 11-year UV flux variations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Hines (1974) speculated that solar-induced modifications of the middle and upper atmosphere may alter the transmissivity of the stratosphere to upwardly propagating atmospheric waves. It was suggested that subsequent constructive or destructive interference may result in a change of phase or amplitude of these waves in the troposphere leading to weather or climate changes. The present investigation has the objective to bring together both radiative transfer and planetary wave studies in an effort to assess specifically whether Hines mechanism can be initiated by the solar ultraviolet flux variability assumed to be associated with the 11-year solar cycle. The obtained results suggest that the presently studied mechanism, which links solar-induced zonal wind changes in the stratosphere and mesosphere to planetary wave changes in the troposphere, is not strong enough to cause substantive changes in the troposphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2273-228
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  • 86
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    The solar spectral irradiance between 150 and 200 nm (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The absorption of solar photons controls the composition of the middle atmosphere. Concern about the effects of man's industrial activities on his environment has led to a number of long-term programs related to stratospheric photochemistry. An important part of these programs represents studies of the variability of the sun's solar spectral irradiance. A program to measure the solar ultraviolet flux, both within and outside the earth's atmosphere, has been in progress for a number of years. This program has the objective to develop techniques which would provide an absolute accuracy of at least 5 percent. The amount of satellite instrument degradation is determined on the basis of a comparison of data provided by these instruments with data obtained in connection with rocket flights. It was found that a significant decrease in the solar irradiance below 190 nm occurred between 1980 and 1981.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2265-227
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  • 87
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    Delayed production of sulfuric acid condensation nuclei in the polar stratosphere from El Chichon volcanic vapors (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is pointed out that measurements of the vertical profiles of atmospheric condensation nuclei (CN) have been conducted since 1973. Studies with a new instrument revealed that the CN concentration undergoes a remarkable annual variation in the 30-km region characterized by a large increase in the late winter/early spring period with a subsequent decay during the remainder of the year. The event particles are observed to be volatile at 150 C, suggesting a sulfuric acid-water composition similar to that found in the normal 20 km aerosol layer. The development of about 10 to the 7th metric tons of sulfuric acid aerosol following the injection of sulfurous gases by El Chichon in April 1982, prompted Hofmann and Rosen (1983) to predict a very large CN event for 1983. The present investigation is concerned with the actual observation of the predicted event. Attention is given to the observation of a very large increase of what appear to be small sulfuric acid droplets at 30-km altitude in January 1983 over Laramie, WY, in January 1983.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 2341-235
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  • 88
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    Coupling between the solar wind and the magnetosphere - CDAW 6 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is pointed out that an extensive study of the causes and manifestations of geomagnetic activity has been carried out as part of the sixth Coordinated Data Analysis Workshop, CDAW 6. The present investigation has the objective to determine the coupling between the solar wind and the magnetosphere for the two selected analysis intervals, taking into account, as a basis for the study, the interplanetary field and plasma observations from ISEE 3 and IMP 8 and the geomagnetic activity indicators developed by CDAW 6 participants. The method of analysis employed is discussed, giving attention to geomagnetic indices, upstream parameters, and a cross-correlation analysis. In a description of the obtained results, the March 22, 1979 event is considered along with the March 31 to April 1, 1979 event, and an intercomparison of the events. The relationship between interplanetary indices and the resulting geomagnetic activity for the two CDAW 6 intervals is illustrated.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 1191-119
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  • 89
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    Similarities and contrasts in tectonic and volcanic style and history along the Colorado plateaus-to-basin and range transition zone in Western Arizona: Geologic framework for tertiary extensional tectonics (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The overall temporal and spatial relations between middle Tertiary volcanism and tectonism from the Basin and Range province onto the edge of the Colorado Plateaus province suggest that a single magnetic-tectonic episode affected the entire region more or less simultaneously during this period. The episode followed a post-Laramide (late Eocene through Oligocene) period of 25 million years of relative stability. Middle Tertiary volcanism did not migrate gradually eastward in a simple fashion onto the Colorado Plateau. In fact, late Oligocene volcanism appears to be more voluminous near the Aquarius Mountains than throughout the adjacent Basin and Range province westward to the Colorado River. Any model proposed to explain the cause of extension and detachment faulting in the eastern part of the Basin and Range province must consider that the onset of volcanism appears to have been approximately synchronous from the Colorado River region of the Basin and Range across the transition zone and onto the edge of the Colorado Plateaus.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 152 - 155
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  • 90
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    The effects of strain heating in lithospheric stretching models (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The deformation by stretching of a continental type lithosphere has been formulated so that the problem can be solved by a continuum mechanical approach. The deformation, stress state, and temperature distribution are constrained to satisfy the physical laws of conservation of mass, energy, momentum, and an experimentally defined rheological response. The conservation of energy equation including a term of strain energy dissipation is given. The continental lithosphere is assumed to have the rheology of an isotropic, incompressible, nonlinear viscous, two layered solid.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 145 - 146
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  • 91
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    Geometry of miocene extensional deformation, lower Colorado River Region, Southeastern California and Southwestern Arizona: Evidence for the presence of a regional low-angle normal fault (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The geometry of Miocene extensional deformation, which changes along a 120 km-long, northeast-trending transect from the southestern Chocolate Mountains, southeastern California, to the Trigo and southern Dome Rock Mountains, southwestern Arizona is discussed. Based upon regional differences in the structural response to extension and estimated extensional strain, the transet can be divided into three northwesterly-trending structural domains. From southwest to northeast, these domains are: (1) southestern Chocolate-southernmost Trigo Mountains; (2) central to northern Trigo Mountains; and (3) Trigo Peaks-southern Dome Rock Mountains. All structures formed during the deformation are brittle in style; fault rocks are composed of gouge, cohesive gouge, and local microbreccia. In each structural domain, exposed lithologic units are composed of Mesozoic crystalline rocks unconformably overlain by Oligocene to Early Miocene volcanic and minor interbedded sedimentary rocks. Breccia, conglomerate, and sandstone deposited synchronously with regional extension locally overlie the volcanic rocks. Extensional deformation largely postdated the main phase of volcanic activity, but rare rhyolitic tuff and flows interbedded with the syndeformational clastic rocks suggest that deformation began during the waning stages of valcanism. K-Ar isotopic ages indicate that deformation occurred in Miocene time, between about 22 and m.y. ago.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 147 - 151
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  • 92
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    A numerical study of forced lithospheric thinning (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Subsolidus lithospheric thinning by mantle plumes may be involved in the creation of swells, hotspots, and rifts. Among the major questions concerning this process are the timescale on which it occurs and the structure of the plumes. The lithosphere is known to have been substantially thinned in 10 Ma or less. Current studies are focused on the lithospheric thinning by time-dependent plumes hypothesized to have large temperature differences across them.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 133 - 134
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  • 93
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    Kinematics of a large-scale intraplate extending lithosphere: The Basin-Range (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Upper lithospheric structure of the Cordilleran Basin Range (B-R) is characterised by an E-W symmetry of velocity layering. The crust is 25 km thick on its eastern active margin, thickening to 30 km within the central portion and thinning to approx. 25 km on the west. Pn velocities of 7.8 to 7.9 km/s characterize the upper mantle low velocity cushion, 7.4 km/s to 7.5 km/s, occurs at a depth of approx. 25 km in the eastern B-R and underlies the area of active extension. An upper-crustal low-velocity zone in the eastern B-R shows a marked P-wave velocity inversion of 7% at depths of 7 to 10 km also in the area of greatest extension. The seismic velocity models for this region of intraplate extension suggest major differences from that of a normal, thermally underformed continental lithosphere. Interpretations of seismic reflection data demonstrate the presence of extensive low-angle reflections in the upper-crust of the eastern B-R at depths from near-surface to 7 to 10 km. These reflections have been interpreted to represent low-angle normal fault detachments or reactivated thrusts. Seismic profiles across steeply-dipping normal faults in unconsolidated sediments show reflections from both planar to downward flatening (listric) faults that in most cases do not penetrate the low-angle detachments. These faults are interpreted as late Cenozoic and cataclastic mylonitic zones of shear displacement.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 135 - 137
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  • 94
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    Cenozoic extension and magmatism in Arizona (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The Basin and Range Province of Arizona was the site of two episodes of Cenozoic extension that can be distinguished on the basis of timing, direction and style of extension, and associated magmatism. The first episode of extension occurred during Oligocene to mid-Miocene time and resulted in the formation of low-angle detachment faults, ductile shear zones (metamorphic core complexes), and regional domains of tilted fault blocks. Evidence for extreme middle Tertiary crustal extension in a NE to SW to SW to ENE to WSW direction has been recognized in various parts of the Basin and Range of Arizona, especially in the Lake Mead area and along the belf of metamorphic core complexes that crosses southern Arizona from Parker to Tucson. New geologic mapping and scrutiny of published geologic maps indicates that significant middle Tertiary extension is more widely distributed than previously thought. The state can be subdivided into regional tilt-block domains in which middle Tertiary rocks dip consistently in one direction. The dip direction in any tilt-block domain is generally toward the breakaway of a low-angle detachment fault that underlies the tilt-block domain; we interpret this an indicating that normal faults in the upper plate of a detechment fault are generally synthetic, rather than antithetic, with respect to the detachment fault.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 128 - 132
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  • 95
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    Heat flow and thermal processes in the Jornada delMuerto, New Mexico (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Most heat flow data in rifts are uncertain largely because of hydrologic disturbances in regions of extensive fracturing. Estimates of heat flow in deep petroleum tests within a large basin of the Rio Grande rift, which has suffered little syn-rift fracturing, may begin to provide clearer insight into the relationships between high heat flow and crustal thinning processes. The Jornada del Muerto is a large basin located in the Rio Grande rift of south central New Mexico. The region of interest within the Jornada del Muerto is centered about 30 km east of the town of Truth or Consequences, and is approximately 60 km north-south by 30 km east-west. High heat flows are estimated for the region. Values increase from about 90 mWm(-2) in the northern part of the study area to about 125 mWm(-2) in the southern part. These high heat flows are rather enigmatic because in the immediate vicinities of the sites there is little evidence of Cenozoic volcanism or syn-rift extensional tectonics. It is suggested that the geothermal anomaly in the southern Jornada del Muerto (approx. 125 to approx. 95 mWm(-2) results from some type of mass movement-heat transfer mechanism operating in the crust just below the elastic layer. This conclusion is consistent with the geologic and geophysical data which describe a thin crust, apparently devoid of features indicative of extensional-tectonics in the upper part of the lastic crust.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 123 - 127
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  • 96
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    Late Precambrian aulacogens of the North China craton (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: According to tectonic styles, the Precambrian evolution history of the North China craton may be subdivided into four stages: (1) Archean consolidation in 3.5 to 2.5 Ga, (2) Early Proterozoic rifting in 2.5 to 1.8 Ga, (3) Late Precambrian aulacogen in 1.8 to 0.8 Ga and (4) Platform regime after 0.8 Ga. In the Late Precambrian aulacogen stage of the North China craton there were two main aulacogens, Yanliao and Zhongtiao (Y and Z), developed in Middle Proterozoic time with an age 1.8 to 1.0 Ga. Their NE trend caused them to meet together in the central part of the craton and build up one great Y-Z aulacogen throughout the craton.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 115 - 117
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  • 97
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    Radial rift and block tectonics around the Tharsis bulge: Introductional postulation (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Although the Vallis Marineris canyon and radial fossae grabens have been extensively studied, their origin and formation mechanism is still the subject of numerous questions. Possible rift formation is only one point of view and does not explain the rifting mechanism and the radial pattern of these structures around the Tharsis bulge. Both active and passive rifting must be taken into account. According to the active mechanism the building of a colcanic complex like the Tharsis bulge is caused by the rising of a huge mantle plume and adjoining extrusions which tap the generated magma. The surrounding fossae and valley structures are caused by more passive crustal rifting due to tensional failure of the surface layers. The main rising mantle plume activated and regenerated failure patterns radial to the centre of activity. These radial zones of weakness are then most easily utilized by the rising mantle plume. Deep zones of weakness regulate the penetration and distribution of hot mantle rock into upper levels while, contrarily, the effective impingement of the hot mantle plume into the lithosphere opens up new weakness zones.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extention on Continents and Planets; p 118 - 122
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  • 98
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    Low-angle normal faults-low differential stress at mid crustal levels (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A simple model for frictional slip on pre-existing faults that considers the local stress state near the fault and the effect of non-hydrostatic fluid pressures predicts that low-angle normal faulting is restricted to areas of the crust characterized by low differential stress and nearly lithostatic fluid pressures. The model considers frictional slip on a cohesionless low-angle normal fault governed by the failure criterion tau = mu sub f (sigma (*) sub n) =mu sub f (sigma sub n - P sub f) where tau and sigma sub n are the shear and normal stresses across the fault plane, mu sub f is the static coefficient of friction, and P sub f is the pore fluid pressure. As a first approximation, the model considers a vertical greatest principal compressive stress, sigma sub 1. It is apparent that if slip on low-angle normal faults is governed by the avove frictional failure criterion, slip on the low-angle normal fault occurs only if the least effective principal stress, sigma (*) sub 3 = sigma sub 3 - P sub f, is tensile, whenever tan superscrip -1(mu sub f d, where d is the dip of the fault. If detachment faulting occurs at any significant depth in the crust, P sub f sigma sub 3 is required. In light of this conclusion I allow P sub f to vary as necessary to allow slip on the low-angle normal fault.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 113 - 114
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  • 99
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    Low-angle normal faulting and isostatic response in the Gulf of Suez: Evidence from seismic interpretation and geometric reconstruction (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Tectonic extension within continental crust creates a variety of major features best classed as extensional orogens. These features have come under increasing attention in recent years, with the welding of field observation and theoretical concepts. Most recent advances have come from the Basin and Range Province of the southwestern United States and from the North Sea. Application of these geometric and isostatic concepts, in combination with seismic interpretation, to the southern Gulf of Suez, an active extensional orogen, allows generation of detailed structural maps and geometrically balanced sections which suggest a regional structural model. Geometric models which should prove to be a valuable adjunct to numerical and thermal models for the rifting process are discussed.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 106 - 110
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  • 100
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    The relationship of extensional and compressional tectonics to a Precambrian fracture system in the eastern overthrust belt, USA (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The central and southern Appalachians have a long history of interrelated extensional and compressional tectonics. It is proposed that each episode was controlled by a reactivation of a fracture system in the Precambrian basement. Proprietary seismic-reflection profiles show a system of down-to-the-east Precambrian extensional faults. When under renewed extension, these faults produce features such as the western border faults of Mesozoic basins, and when under compression, probably produce tectonic ramps in the overlying sedimentary cover rocks as well as the spatially and genetically related Alleghenian folds. This system, which parallels the Appalachian trend, is cut by a system of cross-strike hinge or scissors faults that have probable strike-slip movements. Reactivation of this cross-strike system appears to have produced lateral ramps that connect decollements at different stratigraphic levels and caused abrupt changes in fold wavelength along strikes. Continued reactivation of this cross-strike system is suggested by east-west border faults and Precambrian highs between Mesozoic basins. The present activity of this system is suggested by the fact that more than 35% of recent earthquakes are coincident with cross-strike faults and lateral ramps.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 111 - 112
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