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  • GEOPHYSICS  (4,118)
  • 1985-1989  (4,117)
  • 1950-1954  (1)
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  • 1
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    In:  Other Sources
    Publication Date: 2019-01-25
    Description: Following preliminary investigations of the low frequency electric and magnetic fields that may exists in the Earth-ionospheric cavity, measurements were taken with state-of-the art spectrum analyzers. As a follow up to this activity, an investigation was initiated to determine sources and values for possible low frequency signal that would appear in the cavity. The lowest cavity resonance is estimated at about 8 Hz, but lower frequencies may be an important component of our electromagnetic environment. The potential field frequencies produced by the electron were investigated by a classical model that included possible cross coupling of the electric and gravitation fields. During this work, an interesting relationship was found that related the high frequency charge field with the extremely low frequency of the gravitation field. The results of numerical calculations were surprisingly accurate and this area of investigation is continuing. The work toward continued development of a standardized monitoring facility is continuing with the potential of installing the prototype at West Virginia State College early in 1990. This installation would be capable of real time monitoring of ELF signals in the Earth-ionoshpere cavity and would provide some directional information. A high gain, low noise, 1/f frequency corrected preamplifier was designed and tested for the ferrite core magnetic sensor. The potential application of a super conducting sensor for the ELF magnetic field detection is under investigation. It is hoped that a fully operational monitoring network could pinpoint the location of ELF signal sources and provide new information on where these signals originate and what causes them, assuming that they are natural in origin.
    Keywords: GEOPHYSICS
    Type: Maryland Univ., The 1989 NASA-ASEE Summer Faculty Fellowship Program in Aeronautics and Research; p 27
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  • 2
    Publication Date: 2019-01-25
    Description: The response of mesospheric ozone and temperature to short term solar ultraviolet variations related the the 27 day rotation of the Sun has been recently detected from analysis of satellite measurements. A systematic depletion of ozone was detected near 70 km, which is attributed to solar Lyman alpha photodissociation of water vapor with subsequent catalytic destruction of O(x) by HO(x) and temperature feedback effects resulting from the unexpectedly strong temperature/UV response near 70 km. The nature of latitudinal and semiannual variations in the ozone/UV and temperature/UV response were isolated. Observed variations are compared to theoretical models.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 67
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  • 3
    Publication Date: 2019-01-25
    Description: There are given results of the numerical experiments on modelling the influence of solar activity on chemical composition and temperature of the middle atmosphere. The consideration is made for peculiarities of solar activity impact under different values of antropogenic pollution of the atmosphere with chlorofluorocarbons and other stuff.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 117
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  • 4
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    In:  Other Sources
    Publication Date: 2019-01-25
    Description: An inverse Poisson integral technique was used to determine a gravity field on the geoid which, when continued by analytic free space methods to the topographic surface, agrees with the observed field. The computation is performed in three stages, each stage refining the previous solution using data at progressively increasing resolution (1 x 1 deg, 5 x 5', 5/8 x 5/8') from a decreasing area of integration. Reduction corrections are computed at 5/8 x 5/8' granularity by differencing the geoidal and surface values, smoothed by low-pass filtering and sub-sampled at 5' intervals. The 1 x 1 deg averages of the reduction corrections thus obtained for 172 1 x 1 deg squares in western North America are discussed. The 1 x 1 deg mean reduction corrections are predominantly positive, varying from -3 to +15 mgal, with values in excess of 5 mgal for 26 squares. Their mean and rms values are +2.4 and 3.6 mgal respectively and they correlate well with the mean terrain corrections. The mean and rms contributions from the three stages of computation are: 1 x 1 deg stage +0.15 and 0.7 mgal; 5 x 5' stage + 1.0 and 1.6 mgal; and 5/8 x 5/8' stage +1.3 and 1.8 mgal. These results reflect a tendency for the contributions to become larger and more systematically positive as the wavelengths involved become shorter. The results are discussed in terms of two mechanisms; the first is a tendency for the absolute values of both positive and negative anomalies to become larger when continued downwards and, the second, a non-linear rectification, due to the correlation between gravity anomaly and topographic height, which results in the values continued to a level surface being systematically more positive than those on the topography.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 107
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  • 5
    Publication Date: 2019-01-25
    Description: A great variety of physical mechanisms of possibly solar induced variations in the middle atmosphere has been discussed in the literature during the last decades. The views which have been put forward are often controversial in their physical consequences. The reason may be the complexity and non-linearity of the atmospheric response to comparatively weak forcing resulting from solar activity. Therefore this review focuses on aspects which seem to indicate nonlinear processes in the development of solar induced variations. Results from observations and numerical simulations are discussed.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 116
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  • 6
    Publication Date: 2019-01-25
    Description: New algorithms were derived for computing terrain corrections, all components of the attraction of the topography at the topographic surface and the gradients of these attractions. These algoriithms utilize fast Fourier transforms, but, in contrast to methods currently in use, all divergences of the integrals are removed during the analysis. Sequential methods employing a smooth intermediate reference surface were developed to avoid the very large transforms necessary when making computations at high resolution over a wide area. A new method for the numerical solution of Molodensky's problem was developed to mitigate the convergence difficulties that occur at short wavelengths with methods based on a Taylor series expansion. A trial field on a level surface is continued analytically to the topographic surface, and compared with that predicted from gravity observations. The difference is used to compute a correction to the trial field and the process iterated. Special techniques are employed to speed convergence and prevent oscillations. Three different spectral methods for fitting a point-mass set to a gravity field given on a regular grid at constant elevation are described. Two of the methods differ in the way that the spectrum of the point-mass set, which extends to infinite wave number, is matched to that of the gravity field which is band-limited. The third method is essentially a space-domain technique in which Fourier methods are used to solve a set of simultaneous equations.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 104
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  • 7
    Publication Date: 2018-12-01
    Description: A comparison is made between three climatologies of backscatter measurements in the troposphere and lower stratosphere at CO2 wavelengths. These were obtained from several locations using ground-based and airborne lidar systems. All three measurement sets show similar features, specifically, a high frequency of occurrence of low backscatter over a limited range of values in the middle and upper atmosphere (the 'background mode'). This background mode is important for the design and performance simulation of the prospective satellite sensors that rely on atmospheric aerosols as scattering targets.
    Keywords: GEOPHYSICS
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  • 8
    Publication Date: 2013-08-31
    Description: The purpose is to identify major discrepancies between empirical models and theoretical models and to stress the need for additional observations in the atmosphere and for further laboratory work, since these differences suggest either problems associated with observation techniques or errors in chemical kinetics data (or the existence of unknown processes which appear to play an important role). The model used for this investigation extends from the earth's surface to the lower thermosphere. It includes the important chemical and photochemical processes related to the oxygen, hydrogen, carbon, nitrogen and chlorine families. The chemical code is coupled with a radiative scheme which provides the heating rate due to absorption of solar radiation by ozone and the cooling rate due to the emission and absorption of terrestrial radiation by CO2, H2O and O3. The vertical transport of the species is expressed by an eddy diffusion parameterization.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP. Volume 31: Reference Models of Trace Species for the COSPAR International Reference Atmosphere; p 117-125
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  • 9
    Publication Date: 2013-08-31
    Description: In this analysis, a reference background stratospheric aerosol optical model is developed based on the nearly global SAGE 1 satellite observations in the non-volcanic period from March 1979 to February 1980. Zonally averaged profiles of the 1.0 micron aerosol extinction for the tropics and the mid- and high-altitudes for both hemispheres are obtained and presented in graphical and tabulated form for the different seasons. In addition, analytic expressions for these seasonal global zonal means, as well as the yearly global mean, are determined according to a third order polynomial fit to the vertical profile data set. This proposed background stratospheric aerosol model can be useful in modeling studies of stratospheric aerosols and for simulations of atmospheric radiative transfer and radiance calculations in atmospheric remote sensing.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP. Volume 31: Reference Models of Trace Species for the COSPAR International Reference Atmosphere; p 109-116
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  • 10
    Publication Date: 2013-08-31
    Description: A nearly global set of data on the nitric acid distribution was obtained for seven months by the Limb Infrared Monitor of the Stratosphere (LIMS) experiment on the Nimbus 7 spacecraft. The evaluation of the accuracy, precision, and resolution of these data is described, and a description of the major features of the nitric acid distributions is presented. The zonal mean for nitric acid is distributed in a stratospheric layer that peaks near 30 mb, with the largest mixing ratios occurring in polar regions, especially in winter.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP. Volume 31: Reference Models of Trace Species for the COSPAR International Reference Atmosphere; p 85-98
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  • 11
    Publication Date: 2013-08-31
    Description: Water vapor is an important minor constituent in the studies of the middle atmosphere for a variety of reasons, including its role as a source for active HO(y) chemicals and its use in analysis of transport processes. A number of in situ and remote techniques were employed in the determination of water vapor distributions. Two of the more complete data sets were used to develop an interim reference profile. First, there are the seven months of Nimbus 7 limb infrared monitor of the stratosphere (LIMS) data obtained during Nov. 1978 to May 1979 over the range 64S to 84N latitude and from about 100 to 1 mb in the mid-mesosphere at several fixed Northern Hemisphere mid-latitude sites. These two data sets were combined to give a mid-lattitude, interim reference water vapor profile for the entire vertical range of the middle atmosphere and with accuracies of better than 25 percent. The daily variability of stratospheric water vapor profiles about the monthly mean was also established from these data sets for selected months. Information is also provided on the longitudinal variability of LIMS water vapor profiles about the daily, weekly, and monthly zonal means. Generally, the interim reference water vapor profile and its variability are consistent with prevailing ideas about chemistry and transport.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP. Volume 31: Reference Models of Trace Species for the COSPAR International Reference Atmosphere; p 50-66
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  • 12
    Publication Date: 2013-08-31
    Description: Improvements are provided for the ozone reference model which is to be incorporated in the COSPAR International Reference Atmosphere (CIRA). The ozone reference model will provide considerable information on the global ozone distribution, including ozone vertical structure as a function of month and latitude from approximately 25 to 90 km, combining data from five recent satellite experiments (Nimbus 7 LIMS, Nimbus 7 SBUV, AE-2 SAGE, Solar Mesosphere Explorer (SME) UVS, and SME IR). The improved models are described and use reprocessed AE-2 SAGE data (sunset) and extend the use of SAGE data from 1981 to the period 1981-1983. Comparisons are shown between the ozone reference model and various nonsatellite measurements at different levels in the middle atmosphere.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP. Volume 31: Reference Models of Trace Species for the COSPAR International Reference Atmosphere; p 37-49
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  • 13
    Publication Date: 2013-08-31
    Description: Models of ozone vertical structure were generated that were based on multiple data sets from satellites. The very good absolute accuracy of the individual data sets allowed the data to be directly combined to generate these models. The data used for generation of these models are from some of the most recent satellite measurements over the period 1978 to 1983. A discussion is provided of validation and error analyses of these data sets. Also, inconsistencies in data sets brought about by temporal variations or other factors are indicated. The models cover the pressure range from from 20 to 0.003 mb (25 to 90 km). The models for pressures less than 0.5 mb represent only the day side and are only provisional since there was limited longitudinal coverage at these levels. The models start near 25 km in accord with previous COSPAR international reference atmosphere (CIRA) models. Models are also provided of ozone mixing ratio as a function of height. The monthly standard deviation and interannual variations relative to zonal means are also provided. In addition to the models of monthly latitudinal variations in vertical structure based on satellite measurements, monthly models of total column ozone and its characteristic variability as a function of latitude based on four years of Nimbus 7 measurements, models of the relationship between vertical structure and total column ozone, and a midlatitude annual mean model are incorporated in this set of ozone reference atmospheres. Various systematic variations are discussed including the annual, semiannual, and quasibiennial oscillations, and diurnal, longitudinal, and response to solar activity variations.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP. Volume 31: Reference Models of Trace Species for the COSPAR International Reference Atmosphere; p 1-36
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  • 14
    Publication Date: 2013-08-31
    Description: Incoherent scatter radar (ISR) has become the most powerful means of studying the ionosphere from the ground. Many of the ideas and methods underlying the troposphere and stratosphere (ST) radars have been taken over from ISR. Whereas the theory of refractive index fluctuations in the lower atmosphere, depending as it does on turbulence, is poorly understood, the theory of the refractivity fluctuations in the ionosphere, which depend on thermal fluctuations, is known in great detail. The underlying theory is one of the most successful theories in plasma physics, and allows for many detailed investigations of a number of parameters such as electron density, electron temperature, ion temperature, electron mean velocity, and ion mean velocity as well as parameters pertaining to composition, neutral density and others. Here, the author reviews the fundamental processes involved in the scattering from a plasma undergoing thermal or near thermal fluctuations in density. The fundamental scattering properties of the plasma to the physical parameters characterizing them from first principles. He does not discuss the observation process itself, as the observational principles are quite similar whether they are applied to a neutral gas or a fluctuating plasma.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Kyoto Middle Atmosphere Program. Handbook for MAP. Volume 30: International School on Atmospheric Radar; p 333-364
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  • 15
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    In:  CASI
    Publication Date: 2013-08-31
    Description: A review of the history of radar techniques which have been applied to atmospheric observation is given. The author starts with ionosphere observation with the ionosonde, symbolizing as it does the earliest history of radar observation, and proceeds to later developments in radar observation such as the use of partial reflection, meteor, and incoherent scatter radars. Mesosphere stratosphere troposphere (MST) radars are discussed in terms of lower atmosphere observation.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Kyoto Middle Atmosphere Program. Handbook for MAP. Volume 30: International School on Atmospheric Radar; p 1-18
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  • 16
    Publication Date: 2013-08-31
    Description: The Global Positioning System (GPS) data collected in southern California from 1986 to 1989 indicate considerable strain accumulation across the Imperial Valley. Displacements are computed at 29 stations in and near the valley from 1986 to 1988, and at 11 sites from 1988 to 1989. The earlier measurements indicate 5.9 +/- 1.0 cm/yr right-lateral differential velocity across the valley, although the data are heavily influenced by the 1987 Superstition Hills earthquake sequence. Some measurements, especially the east-trending displacements, are suspects for large errors. The 1988 to 1989 GPS displacements are best modeled by 5.2 +/- 0.9 cm/yr of valley crossing deformation, but rates calculated from conventional geodetic measurements (3.4 to 4.3 cm/yr) fit the data nearly as well. There is evidence from GPS and Very Long Base Interferometry (VLBI) observations that the present slip rate along the southern San Andreas fault is smaller than the long-term geologic estimate, suggesting a lower earthquake potential than is currently assumed. Correspondingly, a higher earthquake potential is indicated for the San Jacinto fault. The Imperial Valley GPS sites form part of a 183 station network in southern California and northern Baja California, which spans a cross-section of the North American-Pacific plate boundary.
    Keywords: GEOPHYSICS
    Type: NASA-CR-187788 , NAS 1.26:187788
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  • 17
    Publication Date: 2013-08-31
    Description: The correlation between lower ionosphere disturbances, geomagnetic variations and radiowave absorption is an important geophysical problem. The correlation is investigated between the electron density profile structure and riometer absorption, and between the absorption and the H-component magnetic field, in order to determine the relation between the (e)-profile parameters and the geomagnetic field variations.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 236-239
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  • 18
    Publication Date: 2013-08-31
    Description: Solar terrestrial researches have revealed substantial meaning of nonsteady events on the Sun, mainly solar flares, for the processes taking place in ionosphere. Solar flares result in the numerous consequences, account and prediction of which become necessary in our days. It is well known, that ionospheric disturbances following solar flares cause strong disturbances in the ionosphere, which severely violate radio systems (communication, navigation, etc.). Possibilities of sudden short wave fadeouts (SWF) prediction are considered.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 219-222
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  • 19
    Publication Date: 2013-08-31
    Description: In order to clarify the question of solar periods in absorption, the pattern was studied of the solar Lyman-alpha radiation (the principal ionizing agent of the lower ionosphere) and of the radio wave absorption at five widely spaced places in Europe. When the solar Lyman-alpha flux variability is very well developed, then it dominates in the lower ionospheric variability. The most pronounced Lyman-alpha variation on time scale day-month is the solar rotation variation (about 27 days). When the Lyman-alpha variability is developed rather poorly, as it is typical for periods dominated by the 13.5 day variability, then the lower ionospheric variability appears to be dominated by variations of meteorological origin. The conclusions hold for all five widely spaced placed in Europe.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 215-218
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  • 20
    Publication Date: 2013-08-31
    Description: As shown by ground-based absorption measurements, the lower ionospheric plasma is markedly controlled by the structure of the IMF. Whereas in high auroral and subauroral latitudes this effect is very pronounced, in midlatitudes its influence is less important. A comparison of these results with satellite data of the IMF and the solar wind speed confirms the important role of these components, not only during special events but also for the normal state of the ionospheric D region plasma.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 196-202
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  • 21
    Publication Date: 2013-08-31
    Description: The variations of solar and geomagnetic activity may affect the thermosphere circulation via plasma heating and electric fields, especially at high latitudes. The possibility exists that the energy involved in auroral and magnetic storms can produce significant changes of mesosphere and lower thermosphere wind systems. A study of global radar measurements of winds at 80 to 100 km region revealed the short term effects (correlation between wind field and geomagnetic storms) and long term variations over a solar cycle. It seems likely that the correlation results from a modification of planetary waves and tides propagated from below, thus altering the dynamical regime of the thermosphere. Sometimes the long term behavior points rather to a climatic variation with the internal atmospheric cause than to a direct solar control.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 156-163
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  • 22
    Publication Date: 2013-08-31
    Description: A new improved model for cosmic rays-middle atmosphere interaction is developed. The ionization q(h)-profile dependence on penetrating high energy particles composition (protons, alpha-particles and heavier nuclei) and energy spectra (solar activity modulation included) are investigated. A computer program, realizing the Gaussian algorithm for solving of multidimensional integrals is created. The corresponding electron density profiles N(h) at solar minimum and maximum are obtained.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 147-150
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  • 23
    Publication Date: 2013-08-31
    Description: It is tempting to speculate on the possibility that solar flares sometimes are the initial cause of and atmospheric disturbance, which cumulative effect may give rise to a correlation at the 11 year timescale. Reasons to reconsider the possible relevance of solar flare response studies are stated. The discovery of the apparently decisive role of the Quasi-Biennial Oscillations (QBO) in establishing the atmospheric response pattern to solar forcing may throw new light on some of the earlier published relations. Reanalysis of old data in some cases may be advisable. Data on solar flares and their effects on the earth's atmosphere might be a promising candidate for reexamination.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 22-26
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  • 24
    Publication Date: 2013-08-31
    Description: The method of empirical orthogonal functions (EOF) was applied to a 10-year data set of outgoing longwave radiation. Spherical harmonic functions are used as a basis set for producing equal area map results. The following findings are noted. The first EOF accounts for 66 percent of the variance. After that, each EOF accounts for only a small variance, forming a slowly converging series. The first two EOF's describe mainly the annual cycle. The third EOF is primarily the semiannual cycle although many other EOF's also contain significant semiannual parts. These results reaffirm those based on a shorter data set. In addition, a much stronger spring/fall mode was found in the central equatorial Pacific Ocean for the second EOF than was found earlier. This difference is attributed to the use of broadband radiometer data which were available for the present study. The earlier study used data from a window channel instrument which is not as sensitive to water vapor variations. The fourth EOF describes much of the 1976 to 1977 and 1982 to 1983 ENSO phenomena. There is typically a gap in the spectrum between a semiannual peak and the annual cycle for all but the first EOF. A semiannual OLR dipole straddles the Asian-Australian monsoon track.
    Keywords: GEOPHYSICS
    Type: NAS 1.15:103465 , NASA-TM-103465
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  • 25
    Publication Date: 2013-08-31
    Description: The Gravity Probe-B Mission will carry the Stanford Gyroscope relativity experiment into orbit in the mid 1990's, as well as a Global Positioning System (GPS) receiver whose tracking data will be used to study the earth gravity field. Estimates of the likely quality of a gravity field model to be derived from the GPS data are presented, and the significance of this experiment to geodesy and geophysics are discussed.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 159-163
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  • 26
    Publication Date: 2013-08-31
    Description: The NASA Ocean Topography Experiment satellite TOPEX will carry a microwave altimeter accurate to a few centimeters for the measurement of ocean height. The capability can be fully exploited only if TOPEX altitude can be independently determined to 15 cm or better. This in turn requires an accurate gravity model. The gravity will be tuned with selected nine 10-day arcs of laser ranging, which will be the baseline tracking data type, collected in the first six months of TOPEX flight. TOPEX will also carry onboard an experimental Global Positioning System (GPS) flight receiver capable of simultaneously observing six GPS satellites above its horizon to demonstrate the capability of GPS carrier phase and P-code pseudorange for precise determination of the TOPEX orbit. It was found that subdecimeter orbit accuracy can be achieved with a mere two-hour arc of GPS tracking data, provided that simultaneous measurements are also made at six of more ground tracking sites. The precision GPS data from TOPEX are also valuable for refining the gravity model. An efficient technique is presented for gravity tuning using GPS measurements. Unlike conventional global gravity tuning, this technique solves for far fewer gravity parameters in each filter run. These gravity parameters yield local gravity anomalies which can later be combined with the solutions over other parts of the earth to generate a global gravity map. No supercomputing power will be needed for such combining. The approaches used in this study are described and preliminary results of a covariance analysis presented.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 155-158
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  • 27
    Publication Date: 2013-08-31
    Description: Model computations show that changes of sampling interval introduce only 0.3 cm changes, whereas zero padding provides an improvement of more than 5 cm in the fast Fourier transformation (FFT) generated geoid. For the Global Positioning System (GPS) survey of Franklin County, Ohio, the parameters selected as a result of model computations, allow large reduction in local data requirements while still retaining the cm accuracy when tapering and padding is applied. The results are shown in tables.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 92-99
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  • 28
    Publication Date: 2013-08-31
    Description: Different types of gravity prediction methods for local and regional gravity evaluation are developed, tested, and compared. Four different test areas were particularly selected in view of different prediction requirements. Also different parts of the spectrum of the gravity field were considered.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 81-84
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  • 29
    Publication Date: 2013-08-31
    Description: The most widely known modern method for estimating gravity field values from observed data is least-squares collocation. Its advantages are that it can make estimates at arbitrary locations based on irregularly spaced observations, and that it makes use of statistical information about errors in the input data while providing corresponding information about the quality of the output estimates. Disadvantages of collocation include the necessity of inverting square matrices of dimension equal to the number of data values and the need to assume covariance models for the gravity field and the data errors. Fourier methods are an important alternative to collocation; having the advantage of greater computational efficiency, but requiring data estimates to be on a regular grid and not using or providing statistical accuracy information. The GEOFAST algorithm is an implementation of collocation that achieves high computational efficiency by transforming the estimation equations into the frequency domain where an accurate approximation may be made to reduce the workload. The forward and inverse Fast Fourier Transforms (FFTs) are utilized. The accuracy and computational efficiency of the GEOFAST algorithm is demonstrated using two sets of synthetic gravity data: marine gravity for an ocean trench region including wavelengths longer than 200 km; and local land gravity containing wavelengths as short as 5 km. These results are discussed along with issues such as the advantages of first removing reference field models before carrying out the estimation algorithm.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 77-80
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  • 30
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    In:  CASI
    Publication Date: 2013-08-31
    Description: The Rapid Geodetic Survey System (RGSS) is a system employing a high-accuracy gimbaled inertial platform. It provides a cost-effective capability for accurate direct measurement of the change in position, elevation, gravity intensity and deflection of the vertical from an initial point. The RGSS is an adaptation of the production version of the U.S. Army Position and Azimuth Determining System (PADS). Several hardware and software enhancements to improve the performance of the system, primarily for gravity vector survey, have occurred over the last few years. The basic principles for the control of error in the survey measurements due to noise and systematic error are discussed below. Actual acceptance test results for the RGSS which indicate an inherent capability of the system to measure change in the deflection of the vertical to a few-tenths of an arcsecond over survey periods of one to two hours using careful survey techniques are also presented. Finally a simple method to extend the capability of the system for longer duration surveys is indicated.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 60-63
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  • 31
    Publication Date: 2013-08-31
    Description: One of the six absolute gravity instruments developed and built by the Joint Institute for Laboratory Astrophysics (JILA) between 1982 and 1985 was tested under a variety of environmental conditions between May 1987 and 1988. Of the 30 sites visited during this period, 10 were occupied more than once. These reobservations indicate repeatability between 1 and 4 microgals.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 64-67
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  • 32
    Publication Date: 2013-08-31
    Description: At the turn of the century, only pendulum apparatuses and torsion balances were available for general exploration work. Both of these early techniques were cumbersome and time-consuming. It was no wonder that the development of the gravity meter was welcomed with a universal sigh of relief. By 1935 potential field measurements with gravity meters supplanted gradient measurements with torsion balances. Potential field measurements are generally characterized by three types: absolute - measurements are made in fundamental units, traceable to national standards of length and time at each observation site; relative with absolute scale - differences in gravity are measured in fundamental units traceable to national standards of length and time; and relative - differences in gravity are measured with arbitrary scale. Improvements in the design of gravity meters since their introduction has led to a significant reduction in size and greatly increased precision. As the precision increased, applications expanded to include the measurement of crustal motion, the search for non-Newtonian forces, archeology, and civil engineering. Apart from enhancements to the astatic gravity meter, few developments in hardware were achieved. One of these was the vibrating string gravity meter which was developed in the 1950s and was employed briefly for marine and borehole applications. Another is the cryogenic gravity meter which utilizes the stability of superconducting current to achieve a relative instrument with extremely low drift suitable for tidal and secular gravity measurements. An advance in performing measurements from a moving platform was achieved with the development of the straight-line gravity meter. The latter part of the century also saw the rebirth of gradient measurements which offers advantages for observations from a moving platform. Definitive testing of the Bell gradiometer was recently reported.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 56-59
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  • 33
    Publication Date: 2013-08-31
    Description: An important goal of geodesy is to determine the anomalous potential and its derivatives outside of the earth. Representing the surface anomalies by a series of spherical harmonics is useful since it is then possible to do a term by term solution of Laplace's equation and upward continuation. The problem of finding such a spherical harmonic series for anomaly values given on an equiangular surface grid is addressed. (This is a first step toward the more complicated problem of finding a function such that locally averaged values fit a grid of mean anomalies.) Three approaches to this fitting problem are discussed and compared: the discrete Fourier technique, the discrete integral technique, and a new approach. The peculiar nature of the equiangular grid, with its increasing density of (noisy) data toward the poles, causes each method to exhibit a different type of difficulty. The new method is shown to be practical as well as precise since the numerical conditioning problems which appear can be successfully handled by such well-known techniques as a (simple) Kalman filter.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 35-38
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  • 34
    Publication Date: 2013-08-31
    Description: The GEM-T2 is the latest in a series of Goddard Earth Models of the terrestrial field. It was designed to bring modeling capabilities one step closer towards ultimately determining the TOPEX/Poseidon satellite's radial position to an accuracy of 10-cm RMS (root mean square). It also improves models of the long wavelength geoid to support many oceanographic and geophysical applications. The GEM-T2 extends the spherical harmonic field to include more than 600 coefficients above degree 36 (which was the limit for its predecessor, GEM-T1). Like GEM-T1, it was produced entirely from satellite tracking data, but it now uses nearly twice as many satellites (31 vs. 17), contains four times the number of observations (2.4 million), has twice the number of data arcs (1132), and utilizes precise laser tracking from 11 satellites. The estimation technique for the solution has been augmented to include an optimum data weighting procedure with automatic error calibration for the gravitational parameters. Results for the GEM-T2 error calibration indicate significant improvement over previous satellite-only models. The error of commission in determining the geoid has been reduced from 155 cm in GEM-T1 to 105 cm for GEM-T2 for the 36 x 36 portion of the field, and 141 cm for the entire model. The orbital accuracies achieved using GEM-T2 are likewise improved. Also, the projected radial error on the TOPEX satellite orbit indicates 9.4 cm RMS for GEM-T2, compared to 24.1 cm for GEM-T1.
    Keywords: GEOPHYSICS
    Type: NASA-TM-100746 , NAS 1.15:100746 , REPT-89B00244
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  • 35
    facet.materialart.
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    In:  CASI
    Publication Date: 2013-08-31
    Description: The focus of this effort is the development of a global-scale model of aerosol backscatter for laser atmospheric wind sounder (LAWS) design and performance studies. Background parameters are derived from aerosol data sets with global-scale spatial and/or temporal coverage, using objective statistical decomposition and/or a priori stratification based on supplementary data. Backscatter coefficients at the LAWS design wavelength are derived from background aerosol physical, chemical, and optical data, or from direct backscatter measurements at other wavelengths, using background conversion factors. Direct measurements of aerosol backscatter at 10.6 microns from the Royal Signals and Radar Establishment (RSRE) and the Wave Propagation Laboratory (WPL) were selected. The RSRE backscatter data processing code were optimized under low backscatter conditions, performed detailed analyses of collocated intercomparisons between the two lidars, and assisted in the analysis of the long-term backscatter climatologies from the two lidars. Timely presentation of global backscattering experiment (GLOBE) research results to the global geophysical community is required.
    Keywords: GEOPHYSICS
    Type: NASA, Marshall Space Flight Center, NASA(MSFC FY88 Global Scale Atmospheric Processes Research Program Review; p 75-78
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  • 36
    Publication Date: 2013-08-31
    Description: The research is comprised of the following tasks: use of simple analytical and numerical models of a coupled troposphere-stratosphere system to examine the effects of radiation and ozone on planetary wave dynamics and the tropospheric circulation; use of satellite data obtained from the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) instrument and Solar Backscattered Ultraviolet (SBUV) experiment, in conjunction with National Meteorological Center (NMC) data, to determine the planetary wave vertical structures, dominant wave spectra, ozone spectra, and time variations in diabatic heating rate; and synthesis of the modeling and observational results to provide a better understanding of the effects that stratospheric processes have on tropospheric dynamics.
    Keywords: GEOPHYSICS
    Type: NASA, Marshall Space Flight Center, NASA(MSFC FY88 Global Scale Atmospheric Processes Research Program Review; p 55-58
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  • 37
    Publication Date: 2013-08-31
    Description: The modeling groups are listed along with a brief description of the respective models.
    Keywords: GEOPHYSICS
    Type: Two-Dimensional Intercomparison of Stratospheric Models; P 111-140
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  • 38
    Publication Date: 2013-08-31
    Description: Atmospheric sounding of the middle atmosphere by Rayleigh scattering has been performed in France for several years, from two stations with different orographic situations: one in the Alps, the Observatoire de Haute Provence, one on the Atlantic coast at Biscarosse. The vertical profiles of density and temperature are obtained with a temporal and spatial resolution of, respectively, 15 mn and 300 m between 30 and 80 km. A statistical study of the atmospheric fluctuations due to gravity waves was performed and the main results are presented: climatology of the gravity wave activity, distribution of energy versus vertical wave number and altitude, and comparison of the observations at the two sites. Conclusions are presented on the saturation of the wave field, the filtering by the mean wind, the transfer of energy and momentum into the atmosphere.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 488-496
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  • 39
    Publication Date: 2013-08-31
    Description: Wind motions were observed at 60 to 90 km altitudes with the MU radar during daylight hours (0800 to 1600 LT) from 13 to 31 October 1986. Quasi-monochromatic gravity waves were evident on 16 of the 19 days of observations. They were characterized by typical vertical wavelength of 5 to 15 km and intrinsic periods centered at about 9 hours. The propagation direction of the gravity waves, determined by the gravity wave dispersion relation, was mostly equatorward. The vertical wave number spectra of the horizontal components of the mesoscale wind fluctuations are explained well by saturated gravity wave theory. The frequency spectrum of vertical wind component has a slope of + 1/3, while the oblique spectra have a slope of -5/3 up to 4 x 10(-3) (c/s); these agree fairly well with model gravity wave spectra. Doppler shift effects on the frequency spectra are recognized at higher frequencies. Upward flux was determined of horizontal momentum flux induced by waves with periods from 10 min to 8 hours, and westward and northward body forces of 5.1 and 4.0 m/s/day, were estimated respectively.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 469-476
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  • 40
    Publication Date: 2013-08-31
    Description: Wind measurements near the mesopause level were provided in Badary (Eastern Siberia, USSR) by the D1 method using a low frequency (200 kHz) radio transmitter during 1976 to 1986. The seasonal variations of wind level are analyzed and compared with other midlatitude wind measurements and with some theoretical preditions. It is shown that tidal parameters depend not only on latitude but on the longitude as well. The annual variation of diurnal and semidurnal tide (zonal and meridional) have maxima in summer and minima in winter. There are significant differences between annual variations of phases for diurnal and semidiurnal tides. These differences are especially distinct for summer and autumn. There is no systematic seasonal variation of the phase of the semidiurnal tide (average value similar to 6 hours).
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 334-338
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  • 41
    facet.materialart.
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Recent contributions to tidal theory during the last five years are reviewed. Specific areas where recent progress has occurred include: the action of mean wind and dissipation on tides, interactions of other waves with tides, the use of TGCM in tidal studies. Furthermore, attention is put on the nonlinear interaction between semidiurnal and diurnal tides. Finally, more realistic thermal excitation and background wind and temperature models have been developed in the past few years. This has led to new month-to-month numerical simulations of the semidiurnal tide. Some results using these models are presented and compared with ATMAP tidal climatologies.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 317-320
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  • 42
    Publication Date: 2013-08-31
    Description: Atmospheric tides, oscillations in meteorological fields occurring at subharmonics of a solar or lunar day, comprise a major component of middle atmosphere global dynamics. The purpose of the 1982 to 1986 Atmospheric Tides Atmosphere Program (ATMAP) was to foster an interaction between experimentalists, data analysts, and theoreticians and modelers, in order to better understand the physical mechanisms governing tides and their relationships to other scales of motion, and to thereby explain features of observed tidal structures in the mesosphere and lower thermosphere. The ATMAP consisted of seven observational campaigns, five workshops and a climatological study. A historical perspective is provided along with a summary of major results, conclusions, and recommendations for future study which have emerged from the ATMAP.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 280-282
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  • 43
    Publication Date: 2013-08-31
    Description: In the winter of 1983 to 1984, the research institutes of the Soviet Union took an active part in the accomplishment of the project Winter in Northern Europe (MAP/WINE) of the Middle Atmosphere Program. Different methods were used to measure temperature, direction and velocity of wind, turbulence, electron concentration in the lower ionosphere, and radio wave absorption. The study of the stratopheric warmings and the related changes in the mesosphere and lower ionosphere was considered of special importance. The analysis of the obtained data has shown, in particular, that during the stratospheric warmings the western wind in winter time becomes weaker and even reverses. At the same time period the electron concentration and the radio wave absorption in the lower ionosphere are often reduced. It is also observed that the high absorption zones move from west to east. These results confirm the concept about the role of the cyclonic circumpolar vortex in the transport of the auroral air to temperate latitudes and about the appearance of conditions for the winter anomalous radio wave absorption.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 245-250
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  • 44
    Publication Date: 2013-08-31
    Description: Long term observations of relativistic electrons in the earth's outer magnetosphere show a strong solar cycle dependence with a prominent intensity maximum during the approach to solar minimum. This population therefore closely corresponds to the presence of high speed solar wind streams emanating from solar coronal holes. Using a numerical code, the precipitating electron energy deposition in the earth's upper and middle atmosphere were calculated. Observed events (typically persisting several days) would have maximum effect in the 40 to 60 km altitude range with peak energy depositions greater than 110 keV/cu cm-s. It is suggested that this electron population could play an important long term role in modulating lower D region ionization and middle atmospheric ozone chemistry. Methods are described of observing middle atmospheric and lower ionospheric effects of the electrons including balloon, riometer, and space-based ozone sensor systems. A particularly promising approach may involve the monitoring of global Schumann resonance modes which are sensitive to global changes in the properties of the earth-ionosphere cavity. Present work indicates that Schumann resonance properties are moderately correlated with the flux of precipitating relativistic electrons thus offering the possibility of continuously monitoring this aspect of magnetosphere-atmosphere coupling.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 217-219
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  • 45
    facet.materialart.
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Recently an interesting advancement in the study of nonmigrating tides has occurred. There have been two distinct approaches in works on this subject. One is based on mechanistic models as considering nonuniform global distribution of water vapor or heating only on land, solving a set of linear equations. It is found that insolation absorption of the nonuniformly distributed water vapor produces only weak nonmigrating tides in the lower thermosphere; the planetary boundary layer heating on land can explain the enhanced tides on land and those with short vertical wavelengths in the stratosphere. The other approach is novel and uses simulation on the general circulation model (GCM). This realistic model can reproduce tides globally and in many details. The enhancement of two nonmigrating modes as eastward traveling modes with a wave number 3 and westward traveling modes with a wave number 5 is in surprisingly good agreement with observation at sea level, at 700 mb and even at 300 mb.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 293-302
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  • 46
    Publication Date: 2013-08-31
    Description: Continuous radar measurements of the wind oscillations caused by the solar diurnal and semidiurnal tides in the 80 to 110 km region of the atmosphere at the geographically conjugate stations of Adelaide (35 S, 138 E) and Kyoto (35 N, 136 E) are compared for the period 1983 to 1985. At the solstices it is found for both the 24- and 12-hr tides that the NS and EW oscillations tend to be in-phase and out-of-phase, respectively, behavior which indicates strong tidal asymmetries. The asymmetries in the 12-hr tide are consistent with a strong contribution from the (2,3) mode while the asymmetries in the 24-hr tide are ascribed to the effects of mean winds and dissipation acting to distort the (1,1) mode as it propagates up through the middle atmosphere.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 283-292
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  • 47
    Publication Date: 2013-08-31
    Description: During the MAP/WINE campaign in winter 1983 to 1984 several instrumental techniques, such as meteorological rockets, sounding rockets, MST radar and incoherent scatter radar, were applied to measure wind velocities in the middle atmosphere. Profiles of mean, tidal and fluctuating wind velocities were obtained up to 90 to 100 km altitude. These are compared with profiles from models, measurements at other locations and at other times as well as satellite derived data. The results are discussed in terms of ageostropic winds, planetary waves, tidal modes and the possibility of a saturated gravity wave spectrum in the mesosphere.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 251-270
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  • 48
    Publication Date: 2013-08-31
    Description: During MAP/WINE small scale structure and turbulence in the mesosphere and lower thermosphere was studied in situ by rocket-borne instruments as well as from the ground by remote sensing techniques. The eight salvoes launched during the campaign resulted in a wealth of information on the dynamical structure of these regions. The experimental results are reviewed and their interpretation is discussed in terms of gravity waves and turbulence. It is shown that eddy diffusion coefficients and turbulent energy dissipation rates may be derived from the in situ measurements in a consistent manner. The observations are also shown to be consistent with the hypothesis that turbulence can be created by a process of gravity wave saturation.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 226-236
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  • 49
    Publication Date: 2013-08-31
    Description: While the Langmuir probe controlled by rocket propagation experiments by the University of Illinois at midlatitude revealed the existence of a permanent D region turning point (DTP), similar measurements over the Thumba equatorial station did not clearly bring out the above daytime feature. Moreover, the calibration constant (ratio of electron density to the current drawn by the Langmuir probe) increased with height (in the 70 to 100 km region) in the case of the midlatitude observations whereas the recent measurements over Thumba showed a decrease up to about 90 km followed by an increase above 90 km. Secondly, there is the problem of reconciling the station oriented observations from the COSPAR family with the ground based radio propagation measurements from the URSI family. Thirdly, new information on Winter in Northern Europe (WINE) and in USSR is available by asking for its incorporation into any global model such as the IRI. The results of investigation of the above aspects are presented.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 212-215
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  • 50
    Publication Date: 2013-08-31
    Description: Since February 1985, the 2 MHz narrow beam radar operated by the University of Adelaide in Australia has been used to measure the short term root-mean-square fluctuating velocities of radio wave scatterers in the upper middle atmosphere (80 to 100 km). These measured fluctuations are caused by a mixture of turbulence and gravity waves, and under certain reasonable assumptions the turbulent contribution can be extracted. The results of these measurements were discussed in detail by Hocking (1988). These results are summarized and the data set is extended to include 1987.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 439-442
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  • 51
    Publication Date: 2013-08-31
    Description: Reflection heights of low frequency radio waves in midlatitude summer, which are closely associated with the neutral atmosphere isobaric level of 0.0052 hPa, exhibit a statistically significant downgoing trend from 1962 to 1987. This indicates a systematic decrease of air pressure at 80 km height by 10.3 plus or minus 4.9 percent over this period, to be regarded as a sufficient evidence of a true signal of progressive cooling of the middle atmosphere, expected with the growing content of CO2 and other greenhouse bases in the atmosphere. It is quantitatively consistent with a temperature decrease at the stratopause by about 4 K, as predicted by the recent model of interactive greenhouse and ozone processes of Brasseur and de Rudder (1987).
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 70-71
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  • 52
    Publication Date: 2013-08-31
    Description: Numerical integrations of the structure function of tropospheric inhomogeneities have been performed to assess the impact of water vapor fluctuations on connected element interferometry (CEI). The expectation value of the RMS troposphere error for a differential spacecraft-quasar observation is derived by integrating the spatial refractivity structure function along raypaths to both the spacecraft and quasar from two spatially separated sites. Correlations between the tropospheric conditions at the two sites, which can become significant for short baseline observations, are fully accounted for in this calculation. Temporal effects are treated by assuming a frozen-flow model in which a fixed spatial distribution blows over both sites. Two nominal observation scenarios are considered, along with variations to study the dependence of the resultant differential troposphere errors on baseline length, observation time, source separation angle, and elevation. Consecutive differential observations are found to be almost completely uncorrelated, implying that averaging many repeated differential observations can quickly reduce the troposphere error.
    Keywords: GEOPHYSICS
    Type: The Telecommunications and Data Acquisition Report; p 47-57
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  • 53
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Desert varnish is the dark coat of clay and ferromanganese oxides developed on exposed rock surfaces in arid regions. It forms from the accretion of material from windblown dust. The distribution of desert varnish was mapped in Arizona. It was discovered that desert varnish could be mapped on a regional scale. Well developed desert varnish is common on stable rock surfaces in areas having alkaline soils and less than about 25 cm of annual precipitation. Rock surfaces in areas having more than 40 cm of annual precipitation are generally devoid of desert varnish. An experiment was conducted with varnished desert pavement stone. The stones were broken in half and half was set on a roof in central Illinois from April until October. Removed from the alkaline desert environment, it only took seven months for the varnish to develop an eroded appearance. This experiment graphically illustrates the dependency of desert varnish on alkalinity. In this context, the zones of eroded desert varnish in Arizona indicate that the area of active desert varnish formation has fluctuated, expanding in drier times and contracting/eroding in wetter times.
    Keywords: GEOPHYSICS
    Type: NASA, Ames Research Center, Exobiology and Future Mars Missions; p 19
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  • 54
    Publication Date: 2013-08-31
    Description: One to two month oscillations in D-region absorption are found in seven years of daily f-min data from low latitude stations at Singapore (1N, 104E) and Rarotonga (21S, 160W). Coherency (cross-spectral) analyses reveal that solar flux variations account for much of the f-min variance at these periods. Over the range of periods from 10 to 200 days, statistically significant linear correlation is found between the f-min time series and contemporaneous 10.7 cm solar flux mearurements at periods of 16 to 19 days, the 26 to 29 day solar rotation band, and a broad band covering 43 to 80 day periods.
    Keywords: GEOPHYSICS
    Type: NAS 1.26:184684 , NASA-CR-184684
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  • 55
    Publication Date: 2013-08-31
    Description: A method for the simultaneous solution of dynamic ocean topography, gravity and orbits using satellite altimeter data is described. A GEM-T1 based gravitational model called PGS-3337 that incorporates Seasat altimetry, surface gravimetry and satellite tracking data has been determined complete to degree and order 50. The altimeter data is utilized as a dynamic observation of the satellite's height above the sea surface with a degree 10 model of dynamic topography being recovered simultaneously with the orbit parameters, gravity and tidal terms in this model. PGS-3337 has a geoid uncertainty of 60 cm root-mean-square (RMS) globally, with the uncertainty over the altimeter tracked ocean being in the 25 cm range. Doppler determined orbits for Seasat, show large improvements, with the sub-30 cm radial accuracies being achieved. When altimeter data is used in orbit determination, radial orbital accuracies of 20 cm are achieved. The RMS of fit to the altimeter data directly gives 30 cm fits for Seasat when using PGS-3337 and its geoid and dynamic topography model. This performance level is two to three times better than that achieved with earlier Goddard earth models (GEM) using the dynamic topography from long-term oceanographic averages. The recovered dynamic topography reveals the global long wavelength circulation of the oceans with a resolution of 1500 km. The power in the dynamic topography recovery is now found to be closer to that of oceanographic studies than for previous satellite solutions. This is attributed primarily to the improved modeling of the geoid which has occurred. Study of the altimeter residuals reveals regions where tidal models are poor and sea state effects are major limitations.
    Keywords: GEOPHYSICS
    Type: NAS 1.15:100735 , REPT-89B0111 , NASA-TM-100735
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  • 56
    Publication Date: 2013-08-31
    Description: Two instrument designs for indirect satellite sounding of the atmosphere in the infrared are represented by the High Resolution Infra-Red Sounder, Model 2 (HIRS-2) and by the Advanced Meteorological Temperature Sounder (AMTS). The relative capabilities of the two instruments were tested by simulating satellite measurements from a group of temperature soundings, allowing the two participants to retrieve the temperature profiles from the simulated data, and comparing the results with the original temperature profiles. Four data sets were produced from radiosondes data extrapolated to a suitable altitude, representing continents and oceans, between 30S and 30N. From the information available, temperature profiles were retrieved by two different methods, statistical regression and inversion of the radiative transfer equation. Results show the consequence of greater spectral purity, concomitant increase in the number of spectral intervals, and the better spatial resolution in partly clouded areas. At the same time, the limitation of the HIRS-2 without its companion instrument leads to some results which should be ignored in comparing the two instruments. A clear superiority of AMTS results is shown.
    Keywords: GEOPHYSICS
    Type: NOAA-TR-NESDIS-42 , NASA-CR-185322 , NAS 1.26:185322
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  • 57
    Publication Date: 2013-08-31
    Description: Kilometer wavelength radiation, measured from distant positions over the North Pole and over the Earth's equator, was compared to the area of discrete aurora imaged by several low-altitude spacecraft. Through correlative studies of auroral kilometric radiation (AKR) with about two thousand auroral images, a stereoscopic view of the average auroral acceleration region was obtained. A major result is that the total AKR power increases as the area of the discrete auroral oval increases. The implications are that the regions of parallel potentials or the auroral plasma cavities, in which AKR is generated, must possess the following attributes: (1) they are shallow in altitude and their radial position depends on wavelength, (2) they thread flux tubes of small cross section, (3) the generation mechanism in them reaches a saturation limit rapidly, and (4) their distribution over the discrete auroral oval is nearly uniform. The above statistical results are true for large samples collected over a long period of time (about six months). In the short term, AKR frequently exhibits temporal variations with scales as short as three minutes (the resolution of the averaged data used). These fluctuations are explainable by rapid quenchings as well as fast starts of the electron cyclotron maser mechanism. There were times when AKR was present at substantial power levels while optical emissions were below instrument thresholds. A recent theoretical result may account for this set of observations by predicting that suprathermal electrons, of energies as low as several hundred eV, can generate second harmonic AKR. The indirect observations of second harmonic AKR require that these electrons have mirror points high above the atmosphere so as to minimize auroral light emissions. The results provide evidence supporting the electron cyclotron maser mechanism.
    Keywords: GEOPHYSICS
    Type: NAS 1.26:184993 , NASA-CR-184993
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  • 58
    Publication Date: 2013-08-31
    Description: In the uniqueness part of a geophysical inverse problem, the observer wants to predict all likely values of P unknown numerical properties z=(z sub 1,...,z sub p) of the earth from measurement of D other numerical properties y (sup 0) = (y (sub 1) (sup 0), ..., y (sub D (sup 0)), using full or partial knowledge of the statistical distribution of the random errors in y (sup 0). The data space Y containing y(sup 0) is D-dimensional, so when the model space X is infinite-dimensional the linear uniqueness problem usually is insoluble without prior information about the correct earth model x. If that information is a quadratic bound on x, Bayesian inference (BI) and stochastic inversion (SI) inject spurious structure into x, implied by neither the data nor the quadratic bound. Confidence set inference (CSI) provides an alternative inversion technique free of this objection. Confidence set inference is illustrated in the problem of estimating the geomagnetic field B at the core-mantle boundary (CMB) from components of B measured on or above the earth's surface.
    Keywords: GEOPHYSICS
    Type: NAS 1.26:184839 , NASA-CR-184839
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  • 59
    Publication Date: 2013-08-31
    Description: Although Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) are becoming increasingly important tools for geodynamic studies, their future role may well be fulfilled by using alternative techniques such as those utilizing the signals from the Global Positioning System (GPS). GPS, without the full implementation of the system, already offers a favorable combination of cost and accuracy and has consistently demonstrated the capability to provide high precision densification control in the regional and local areas of the VLBI and SLR networks. This report reviews VLBI and SLR vis-a-vis GPS and outlines the capabilities and limitations of each technique and how their complementary application can be of benefit to geodetic and geodynamic operations. It demonstrates, albeit with a limited data set, that dual-frequency GPS observations and interferometric type analysis techniques make possible the modelling of the GPS orbits for several days with an accuracy of a few meters. The use of VLBI or SLR sites as fiducial stations together with refinements in the orbit determination procedures can greatly reduce the systematic errors in the GPS satellite orbits used to compute the positions of non-fiducial locations. In general, repeatability and comparison with VLBI of the GPS determined locations are of the order of between 2 parts in 10 to the 7th power and 5 parts in 10 to the 8th power for baseline lengths less than 2000 km. This report is mainly a synthesis of problems, assumptions, methods and recent advances in the studies towards the establishment of a GPS-based system for geodesy and geodynamics and is one phase in the continuing effort for the development of such a system. To some, including the author, it seems reasonable to expect within the next few years that more evidence will show GPS to be as a powerful and reliable a tool as mobile VLBI and SLR are today, but largely more economical.
    Keywords: GEOPHYSICS
    Type: REPT-89B00058 , NAS 1.15:100716 , NASA-TM-100716
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  • 60
    Publication Date: 2013-08-31
    Description: The ionospheric electron density and temperature variations is simulated during the equinox transition study in September 1984 and the results are compared with measurements made at Millstone Hill. The agreement between the modeled and measured electron density and temperature for the quiet day (18 September) is very good but there are large differences on the day of the storm (19 September). On the storm day, the measured electron density decreases by a factor of 1.7 over the previous day, while the model density actually increases slightly. The model failure is attributed to an inadequate increase in the ratio of atomic oxygen to molecular neutral densities in the MSIS neutral atmosphere model, for this particular storm. A factor of 3 to 5 increase in the molecular to atomic oxygen density ratio at 300 km is needed to explain the observed decrease in electron density. The effect of vibrationally excited N sub 2 on the electron density were studied and found to be small.
    Keywords: GEOPHYSICS
    Type: NASA-CR-184737 , NAS 1.26:184737
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  • 61
    Publication Date: 2013-08-31
    Description: Comparison of segment development of a number of arcs has shown that consistent relationships between segmentation, volcanism and variable stresses exists. Researchers successfully modeled these relationships using the conceptual model of lithospheric buckling of Yamaoka et al. (1986; 1987). Lithosphere buckling (deformation) provides the needed mechanism to explain segmentation phenomenon; offsets in volcanic fronts, distribution of calderas within segments, variable segment stresses and the chemical diversity seen between segment boundary and segment interior magmas.
    Keywords: GEOPHYSICS
    Type: NASA, Lyndon B.; NASA, Lyndon B. John
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  • 62
    Publication Date: 2013-08-31
    Description: The simplest model for the Matachewan-Hearst Dike (MHD) magmas is assimilation-fractional crystallization (AFC), presumably occurring at the base of the crust during underplating. Subduction zone enriched mantle sources are not required. Trace elements suggest that the mantle sources for the MHD were depleted, but possessed a degree of heterogeneity. Rates of assimilation were approximately 0.5 (= Ma/Mc); the contaminant mass was less than 20 percent. The contaminant was dominated by tonalites-randodiorites, similar to xenoliths and rocks in the Kapuskasing Structural Zone (KSZ). Assimilation of partial melts of light-rare earth and garnet-bearing basaltic precursors may have produced some the MHD magmas. Apparently, previous underplating-AFC processes had already produced a thick crust. The silicic granitoid assimilant for the MHD magmas was probably produced by earlier processing of underplated mafic crust (4, 5, 10, 21 and 30). Calculations suggest that the derived silicic rocks possess negative Ta and Ti anomalies even though they were not the product of subduction.
    Keywords: GEOPHYSICS
    Type: NASA, Lyndon B.; NASA, Lyndon B. John
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  • 63
    Publication Date: 2013-08-31
    Description: The data base for the vertical column abundance of atmospheric hydroxyl (OH) for Fritz Peak Observatory, Colorado (40 N, 105 W), now extends from 1976 through 1988 and is composed of 8849 independent data sets, averaging about 15 percent uncertainty and 20-minute time resolution each. The dominant solar zenith angle (chi) dependence of the OH abundance is characterized by an empirical curve, N(88), which has been updated from N(82) to include all valid data from 1980 through 1988. The chi-dependence of the OH abundance has been, to a first order, removed from the data base by a normalization procedure in which each data point is divided by the N(88,AM) value for the corresponding solar zenith angle. The resulting normalized OH values may then be examined for other systematic effects, particularly for periodic variations. Observations have also been made at Boca Raton, Florida (26 N, 80 W) and at Truk, Federated States of Micronesia (7 N, 152 E). These data bases are much less extensive and, as such, are less amenable to analysis for periodic behaviors. Some comparisons with the Colorado data may be made, however.
    Keywords: GEOPHYSICS
    Type: NAS 1.26:184667 , NASA-CR-184667
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  • 64
    Publication Date: 2013-08-31
    Description: The Portable Instant Display and Analysis Spectrometer (PIDAS) was taken to southwestern Greenland to investigate in situ the potential application of AVIRIS to estimate the mineralogy and composition of rocks exposed in Archean terranes. The goal was to determine the feasibility of using a high spectral resolution scanner to find and study pristine rocks, those that have not been altered by subsequent deformation and metamorphism. The application of AVIRIS data to the problems in Greenland is logical. However, before a costly deployment of the U-2 aircraft to Greenland is proposed, this study was undertaken to acquire the spectral data necessary to verify that mineralogical mapping in the environmental conditions found there is possible. Although field conditions were far from favorable, all of the major objectives of the study were addressed. One of the major concerns was that lichens would obscure the rock surfaces. It was found that the spectral signature of the lichens was distinct from the underlying rocks. Thus, a spectrum of a rock outcrop, with its partial cover of lichens, can be un-mixed into rock and lichen components. The data acquired during the course of this study supports the conclusion that areas of pristine Archean crust can be differentiated from that which has experienced low grade alteration associated with Proterizoic faulting.
    Keywords: GEOPHYSICS
    Type: NASA-CR-182859 , NAS 1.26:182859
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  • 65
    Publication Date: 2013-08-31
    Description: The following subject areas are covered: (1) genetic, spectral, and LANDSAT Thematic Mapper imagery relationship between desert varnish and tertiary volcanic host rocks, southern Nevada; (2) reconnaissance geologic mapping of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada, using multispectral thermal infrared imagery; (3) interregional comparisons of desert varnish; and (4) airborne scanner (GERIS) imagery of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada.
    Keywords: GEOPHYSICS
    Type: NASA-CR-183493 , NAS 1.26:183493
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  • 66
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    In:  CASI
    Publication Date: 2013-08-31
    Description: The worldwide ionospheric data base is scattered over the entire globe. Different data sets are held at different institutions in the U.S., U.S.S.R., Australia, Europe, and Asia. The World Data Centers on the different continents archive and distribute part of the huge data base; the scope and cross section of the individual data holdings depend on the regional and special interest of the center. An attempt is made to pull together all the strings that point toward different ionospheric data holdings. Requesters are provided with the information about what is available and where to get it. An attempt is also made to evaluate the reliability and compatibility of the different data sets based on the consensus in the ionospheric research community. The status and accuracy of the standard ionospheric models are also discussed because they may facilitate first order assessment of ionospheric effects. This is a first step toward an ionospheric data directory within the framework of NSSDC's master directory.
    Keywords: GEOPHYSICS
    Type: NAS 1.15:101823 , NSSDC/WDC-A-R/S-89-03 , NASA-TM-101823
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  • 67
    Publication Date: 2013-08-31
    Description: The polar cap absorption (PCA) events are the most remarkable geophysical phenomena in the high latitude ionosphere. Their effects are extended on the whole polar region in both hemispheres. The PCA events are caused by the intense fluxes of the solar cosmic rays (SCR) which are generated by the solar proton flares. Entering into the Earth's magnetosphere and ionosphere the SCR fluxes create excessive anomal ionization at the ionospheric heights of 50 to 100 km which exceeds usual undisturbed level of ionization in several orders of magnitude. The PCA events can be considered as catastrophic in relation to the polar ionosphere because all radio systems using ionospheric radio channels ceased to operate during these events. On the other hand the abnormally high level of ionization in the ionospheric D region during the PCA events create excellent opportunities to conduct fruitful aeronomical research for the lower ionosphere. Obvious scientific and practical importance of the PCA events leads to publishing of special PCA catalogues. The ionospheric effects caused by the SCR fluxes were profoundly described in the classical paper (Bailey, 1964). Nevertheless several aspects of this problem were not studied properly. An attempt is made to clarify these questions.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 203-209
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  • 68
    Publication Date: 2013-08-31
    Description: Solar activity influences the ionospheric D region. That influence manifests itself both in the form of various solar induced disturbances and in the form of the D region dependence on solar activity parameters (UV-flux, interplanetary magnetic field, solar wind etc.) in quiet conditions. Relationship between solar activity and meteorological control of the D region behavior is considered in detail and examples of strong variations of aeronomical parameters due to solar or meteorological events are given.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 183-191
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  • 69
    Publication Date: 2013-08-31
    Description: Lower thermospheric (90 to 120 km) wind data was acquired by ground based spaced-receiver method (HF, LF) near Irkutsk (52 deg N, 104 deg E). There is interrelated solar and meteorological control of lower thermosphere dynamics. Some features of solar control effects on the wind parameters are discussed.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 164-167
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  • 70
    Publication Date: 2013-08-31
    Description: Solar particle events (SPEs) have been investigated since the late 1960's for possible effects on the middle atmosphere. Solar protons from SPEs produce ionizations, dissociations, dissociative ionizations, and excitations in the middle atmosphere. The production of HO(x) and NO(x) and their subsequent effects on ozone can also be computed using energy deposition and photochemical models. The effects of SPE-produced HO(x) species on the odd nitrogen abundance of the middle atmosphere as well as the SPE-produced long term effects on ozone. Model computations indicate fairly good agreement with ozone data for the SPE-induced ozone depletion caused by NO(y) species connected with the August 1972 SPE. The model computations indicate that NO(y) will not be substantially changed over a solar cycle by SPEs. The changes are mainly at high latitudes and are on time scales of several months, after which the NO(y) drifts back to its ambient levels.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 129-134
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  • 71
    Publication Date: 2013-08-31
    Description: Now there is no good agreement between theoretical and experimental data of ozone (O3) response to 27 13-day solar ultraviolet irradiance variations (SUVIV). But a few days duration SUVIV (accompanied, for example, by solar flare (SF)) has not be studied yet. The amplitudinal, diurnal, seasonal, latitudinal and phase parameters were investigated of ozone and other trace gases of atmosphere to such short term SUVIV.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 82-85
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  • 72
    Publication Date: 2013-08-31
    Description: Earlier studies on the influence of solar activity variations within a 11-year solar cycle on temperature changes in the middle atmosphere revealed that while the temperature in the mesosphere showed strong responses to changes in solar activity, the stratosphere remained almost unaffected. Recent studies showed that when the temperature data were grouped into east or west phase of the equatorial quasi-biennial oscillation (QBO) in stratospheric zonal wind, significant relationships of temperature in the lower stratosphere and troposphere could be obtained with 10.7 cm solar radio flux. Positive correlations in high latitude regions and negative correlations in mid-latitude and tropical regions were obtained during winter when the QBO was in its west phase. During the east phase, converse relationships were indicated. These results inspired this study on the response of solar activity in 11-year cycle on the temperature structure of the middle atmosphere in the two phases of equatorial QBO of zonal wind at 50 mb, in tropics, mid-latitude and antarctic regions.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 39-42
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  • 73
    Publication Date: 2013-08-31
    Description: Recent studies of solar UV related changes of ozone and temperature have considerably improved the understanding of the solar UV and ozone relationship in the middle atmosphere on time scales of a solar rotation. These studies have shown that during periods of high solar activity, ozone in the upper stratosphere has a measurable response to changes in the solar UV flux in accordance with theoretical predictions. The problem of measuring solar response of the stratospheric ozone and temperature on time scales of a solar cycle is more difficult. In the altitude range of 2 mb, the model based calculations, based on plausible scenarios of solar UV variation, suggest a change of less than 4 percent in ozone mixing ratio and 1 to 2 K in temperature. The relative response was studied of the middle atmosphere to solar forcing at 155 and 27 day periods as indicated from the spectral analyses of a number of solar indices.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 68-75
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  • 74
    Publication Date: 2013-08-31
    Description: The suggestion that galactic cosmic rays (GCR) as modulated by the solar wind are the carriers of the component of solar variability that affects weather and climate has been discussed in the literature for 30 years, and there is now a considerable body of evidence that supports it. Variations of GCR occur with the 11 year solar cycle, matching the time scale of recent results for atmospheric variations, as modulated by the quasibiennial oscillation of equatorial stratospheric winds (the QBO). Variations in GCR occur on the time scale of centuries with a well defined peak in the coldest decade of the little ice age. New evidence is presented on the meteorological responses to GCR variations on the time scale of a few days. These responses include changes in the vertical temperature profile in the troposphere and lower stratosphere in the two days following solar flare related high speed plasma streams and associated GCR decreases, and in decreases in Vorticity Area Index (VAI) following Forbush decreases of GCR. The occurrence of correlations of GCR and meteorological responses on all three time scales strengthens the hypothesis of GCR as carriers of solar variability to the lower atmosphere. Both short and long term tropospheric responses are understandable as changes in the intensity of cyclonic storms initiated by mechanisms involving cloud microphysical and cloud electrification processes, due to changes in local ion production from changes in GCR fluxes and other high energy particles in the MeV to low GeV range. The nature of these mechanisms remains undetermined. Possible stratospheric wind (particularly QBO) effects on the transport of HNO3 and other constituents incorporated in cluster ions and possible condensation and freezing nuclei are considered as relevant to the long term variations.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 53-61
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  • 75
    Publication Date: 2013-08-31
    Description: The papers published by Labitzke (1987) and by Labitzke and Van Loon (1988) indicated that the separation of Winter stratospheric data according to the phase of the Quasi-Biennial Oscillation (Q.B.O.) led to a largely improved relationship with the 11 year solar cycle. Since then, this possible relationship has been studied and extended from the surface to the lower thermosphere and its extension to other seasons is in progress. An opportunity is provided to review the state of the problem and to attempt to give a general view of the experimentally observed responses of the atmosphere to solar activity, when considering the phases of the Q.B.O. After a brief recall of the relationship discovered in the winter stratosphere, its extension downwards, upwards and to the other seasons are successively reviewed. The existing models are not adequate right now to represent the solar influence as they only take into account the change in UV flux, but before being able to use the large scale dynamics in a coupled radiative photochemical model, one needs to understand the mechanism able to explain the forcing from the lower atmosphere or the surface which could be induced by a change in solar activity.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 29. Part 1: Extended Abstracts, International Symposium on Solar Activity Forcing of the Middle Atmosphere. Part 2: MASH Workshop, Williamsburg, 1986; p 27-32
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  • 76
    Publication Date: 2013-08-31
    Description: Recent theoretical works have dealt with the identification and evaluation of the physical processes that determine the characteristic scale sizes of discrete auroral arcs. It is broadly acknowledged that a characteristic spatial width of approximately 100 km (at ionospheric heights) results naturally from the ionospheric mapping of the high-altitude magnetospheric convection electric field. However, recent analysis of the spatial power spectral distributions of electric and magnetic field variations has revealed structure at much smaller spatial scales. In this analysis, precipitating auroral electron data from the J-package sensor on the Defense Meteorological Satellite Program satellite is used to study the spatial scale sizes and size distributions of polar auroral arcs. A monotonically decreasing inverse-wavelength spectrum with a slope near unity is common, with no strictly preferred scale sizes, although the scale spectrum does flatten at scales larger than approximately 100 to 200 km. Typical observed widths of the auroral arcs tend to be much smaller than the resistive scale length, and the observed widths do not have a strong dependence on local ionospheric parameters.
    Keywords: GEOPHYSICS
    Type: NASA-CR-186806 , ATR-88(7162)-3 , NAS 1.26:186806
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  • 77
    Publication Date: 2013-08-31
    Description: The programs described were developed to process GEODYN-formatted satellite altimeter data, and to apply the processed results to predict geoid undulations and gravity anomalies of inland sea areas. These programs are written in standard FORTRAN 77 and are designed to run on the NSESCC IBM 3081(MVS) computer. Because of the experimental nature of these programs they are tailored to the geographical area analyzed. The attached program listings are customized for processing the altimeter data over the Black Sea. Users interested in the Caspian Sea data are expected to modify each program, although the required modifications are generally minor. Program control parameters are defined in the programs via PARAMETER statements and/or DATA statements. Other auxiliary parameters, such as labels, are hard-wired into the programs. Large data files are read in or written out through different input or output units. The program listings of these programs are accompanied by sample IBM job control language (JCL) images. Familiarity with IBM JCL and the TEMPLATE graphic package is assumed.
    Keywords: GEOPHYSICS
    Type: NASA-TM-100730 , REPT-89B00106 , NAS 1.15:100730
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  • 78
    Publication Date: 2013-08-31
    Description: The European ARISTOTELES mission aims at the determination of the Earth's gravity field at short wavelength with a global coverage. Gravity gradient measurements will be achieved during six months by the GRADIO instrument onboard a dedicated satellite in a near dawn-dusk sun-synchronous orbit at an altitude of 200 km. The objective is an accuracy of better than 5 mgals for gravity anomalies, at ground level for blocks of 1 x 1 deg. According to present knowledge of the potential, the recovery of higher spherical harmonics (degree and order greater than 30) is of main importance. This leads to focus on the variations of the measured components T(sub ij) of the gravity gradient tensor, at frequencies greater than 5 x 10(exp -3) Hz. The resolution, required for the gradiometer is 10(exp -2) Eotvos (i.e., 10(exp -11)/s squared) with an averaging time of 4 s.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 184-187
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  • 79
    Publication Date: 2013-08-31
    Description: Various space concepts were discussed during the past 20 years for a global improvement of the knowledge of the earth's gravity field. The concepts reach from high-low and low-low satellite-to-satellite tracking via tethered satellite gradiometers to sophisticated superconducting gradiometers. The purpose is to show that starting from one basic equation three criteria are sufficient to typify the various concepts and define the underlying observation model. Furthermore the different error sources, in particular, the time varying part of self-gravitation, and the expected signal size of all six gravity gradient components shall be discussed.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 172-175
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  • 80
    Publication Date: 2013-08-31
    Description: The idea of satellite-to-satellite tracking in the high-low mode has received renewed attention in light of the uncertain future of NASA's proposed low-low mission, Geopotential Research Mission (GRM). The principal disadvantage with a high-low system is the increased time interval required to obtain global coverage since the intersatellite visibility is often obscured by Earth. The U.S. Air Force has begun to investigate high-low satellite-to-satellite tracking between the Global Positioning System (GPS) of satellites (high component) and NASA's Space Transportation System (STS), the shuttle (low component). Because the GPS satellites form, or will form, a constellation enabling continuous three-dimensional tracking of a low-altitude orbiter, there will be no data gaps due to lack of intervisibility. Furthermore, all three components of the gravitation vector are estimable at altitude, a given grid of which gives a stronger estimate of gravity on Earth's surface than a similar grid of line-of-sight gravitation components. The proposed Air Force mission is STAGE (Shuttle-GPS Tracking for Anomalous Gravitation Estimation) and is designed for local gravity field determinations since the shuttle will likely not achieve polar orbits. The motivation for STAGE was the feasibility to obtain reasonable accuracies with absolutely minimal cost. Instead of simulating drag-free orbits, STAGE uses direct measurements of the nongravitational forces obtained by an inertial package onboard the shuttle. The sort of accuracies that would be achievable from STAGE vis-a-vis other satellite tracking missions such as GRM and European Space Agency's POPSAT-GRM are analyzed.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 164-167
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  • 81
    Publication Date: 2013-08-31
    Description: A new, geometrical, first order, nonresonant, frozen orbit theory was developed based on Orlov's uniformly rotating plane of constant inclination. Perturbation spectra generated from a 90th order subset of OSU86F are shown for the ill-fated 1984 JHU/APL SAGE proposal for a pair of TRANSIT satellites at 400 km altitude with a 93.5 deg inclination.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 151-154
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  • 82
    Publication Date: 2013-08-31
    Description: If the geoid and the satellite position are known accurately, satellite altimetry can be used to determine the geostrophic velocity of the surface ocean currents. The purpose of this investigation is to simultaneously estimate the sea surface topography, zeta, the model for the gravity field, and the satellite orbit. Satellite tracking data from fourteen satellites were used; along with Seasat and Geosat altimeter data as well as surface gravity data for the solution. The estimated model of zeta compares well at long wavelengths with the hydrographic model of zeta. Covariance studies show that the geoid is separable from zeta up to degree 9, at which point geoid error becomes comparable to the signal of zeta.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 142-145
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  • 83
    Publication Date: 2013-08-31
    Description: The fitting and proper regression coefficients were made of one hundred seventeen 10 x 10' blocks with observed gravity data and corresponding elevation in the Taiwan Island. To compare five different predicted models, and the proper one for the mean gravity anomalies were determined. The predicted gravity anomalies of the non-observed gravity blocks were decided when the coefficients obtained through the model with the weighted mean method. It was suggested that the mean gravity anomalies of 10 x 10' blocks should be made when comprehensive the observed and predicted data.
    Keywords: GEOPHYSICS
    Type: Ohio State Univ., Progress in the Determination of the Earth's Gravity Field; p 130-133
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