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  • GEOPHYSICS  (465)
  • SOLAR PHYSICS  (256)
  • 1995-1999
  • 1980-1984
  • 1975-1979  (721)
  • 1978  (721)
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  • 1995-1999
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  • 1975-1979  (721)
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  • 1
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The feasibility and scientific objectives of a solar probe were studied by a Mission Definition Group in 1975 and 1976. The orbit analysis program was developed and an extended study of the orbit analysis was done in 1977. The results of these studies are in the Report of the Mission Definition Study (1976) and an E.S.O.C. report (1978), and the reader is referred to these sources for greater details. In this report, only brief discussion on mission concept and objectives, satellite design, orbit, orbit analysis, are presented.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 556-564
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  • 2
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    In:  CASI
    Publication Date: 2006-01-16
    Description: Realistic options for a Solar Probe Mission consistent with known technical, fiscal, and programmatic constraints are identified. A program plan for NASA which includes identification of necessary research and development activities is developed. A baseline mission and a strawman spacecraft design were selected and used to determine the feasibility of meeting the mission requirements and the sensitivity to variations in those requirements.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 521-534
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  • 3
    Publication Date: 2006-01-16
    Description: The magnitude of Doppler signals produced by gravitational wave burst, continuous gravitational waves, and oscillations of the sun interacting with a spacecraft are considered. Expressions are worked out for the appropriate noise entering each measurement. The noise sources considered are the Doppler extractor, fluctuations in the solar wind and the troposphere, and fluctuations in the reference oscillator.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 498-517
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  • 4
    Publication Date: 2006-01-16
    Description: How gravitational radiation affects Doppler tracking is briefly described. The status of the analyses of the sensitivities achievable with the NASA-JPL Deep Space Network(DSN) is given.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 441-449
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  • 5
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The following general picture of the interplanetary dust is presented: (1) size distribution; (2) spatial distribution; (3) composition; (4) dynamics; and (5) origin. The solar probe mission provides a unique opportunity to study the evolution of the interplanetary dust and its eventual destruction near the sun. Two destructive processes (fragmentation and vaporization) of interplanetary dust are discussed.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 411-419
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  • 6
    Publication Date: 2006-01-16
    Description: The discovery of coronal holes led to basic changes in ideas about the structure of the low corona and its expansion into the solar wind. The nature of the energy flux is not understood. Current ideas include enhanced thermal conductivities, extended MHD wave heating, and wave momentum transfer, all in rapidly diverging geometries. There is little feel for the relative importance of these processes. The Solar Probe, with its penetration deep into the solar corona, could lead to observational constraints on their relative importance, and thus to an understanding of the origin of the solar wind. Observations from the Solar Probe will also bear on such questions as to whether small scale "intrastream" structure is common close to the Sun in open field-line regions, whether the properties of the wind are pronouncedly different over closed and open field-line regions at five solar radii, and many others. The resolution of these questions requires measurements of the magnetic field and of the proton and electron distribution functions.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 318-333
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  • 7
    Publication Date: 2006-01-16
    Description: A review is presented of current experimental and theoretical knowledge of plasma waves in the solar wind, with comments on the scientific importance of obtaining plasma wave measurements in the region near the sun with the solar probe. The waves discussed include the acoustic waves and shocks which are thought to be the primary source for heating the solar corona, Alfven waves, ion-cyclotron waves, whistler-mode turbulence, ion-acoustic waves, and electron plasma oscillations associated with solar radio emissions. A discussion is presented of the types of measurements which would be needed to study these waves on the solar probe, the constraints imposed on the spacecraft and the research and development which would be needed to provide the necessary instrumentation.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 281-317
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  • 8
    Publication Date: 2006-01-16
    Description: Representative sets of recent experimental results and theoretical studies are summarized to show the current knowledge of energetic particle phenomena based mainly on observations near 1 AU. Measurements close to the sun of quantities such as particle spectra, charge and isotopic composition, and the flow of particles as a function of time, together with measurements of the plasma, magnetic field, X-rays, and gamma rays will not only reveal the properties of the source region and acceleration mechanisms but will also provide a better knowledge of the physics of the corona. These measurements may also reveal the existence of large scale inhomogeneities in the solar corona. The general requirements for making these measurements on the solar probe are listed. An energetic particle detector system which has the capability of resolving the charge and isotopic composition up to 50 MeV/nucleon may successfully measure the above quantities provided that it can perform under both very low and average intensity levels.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 205-218
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  • 9
    Publication Date: 2006-01-16
    Description: The unique vantage points and viewing geometries afforded by a close-in solar probe are briefly examined with regard to line and continuum measurements of features on the solar disk, the K and F coronas, and the zodiacal light. Common instrument and observing requirements are identified, suggesting that a single instrument could provide much of the necessary observational data on these phenomena.
    Keywords: SOLAR PHYSICS
    Type: JPL A Closeup of the Sun; p 143-154
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  • 10
    Publication Date: 2006-01-12
    Description: The Limb Infrared Monitor of the Stratosphere is used to obtain vertical profiles and maps of temperature and the concentration of ozone, water vapor, nitrogen dioxide, and nitric acid for the region of the stratosphere bounded by the upper troposphere and the lower mesosphere.
    Keywords: GEOPHYSICS
    Type: NASA. Goddard Space Flight Center The Nimbus 7 User's Guide; p 71-104
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  • 11
    Publication Date: 2006-01-12
    Description: Data reduction techniques are developed to compensate for water vapor path delay, a limiting error source in geodetic measurements made with very long baseline interferometry and in radio ranging to spacecraft. It is shown that water vapor path delay is proportional to a linear combination of saturation-corrected sky brightness temperatures, measured on and off the water vapor line. The effects of emission from liquid water droplets in clouds as well as most of the oxygen emission are removed by the off-line channel. Sky brightness temperatures are saturation-corrected or 'linearized' using estimates of effective sky temperatures made from surface temperature. Tipping curves are used to remove instrumental error. Coefficients are found by two methods: from a regression analysis of measured brightness temperatures versus radiosonde measured delay, and from a regression analysis of theoretical brightness temperatures versus radiosonde measured delay. In each case the coefficients are adjusted for differing climatic conditions by measurements of surface temperature, pressure, and relative humidity. Regression solutions are constrained to remove liquid water contributions and to give the correct slope for radiometer versus radiosonde path delay.
    Keywords: GEOPHYSICS
    Type: The Deep Space Network; p 22-30
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  • 12
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The use of Solar Electric Propulsion (SEP) for the Solar Probe Mission is addressed. The dependence of the payload mass on the site of the SEP and the flight time are described on the basis of preliminary data. The range of hardware expected to be available in the 1980's is summarized. There are several classes of optimal low-thrust trajectories for the Solar Probe Mission. These are trajectory types A, B, C corresponding to one, two, or three orbital revolutions, respectively. Plots of transfer trajectories corresponding to type-A, type-A with a Venus Swingby, type-B, and type-C with ab Icarus Rendezvous are shown. A summary of the SEP performance is given.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 544-555
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  • 13
    Publication Date: 2006-01-16
    Description: The Solar Probe will provide an ideal platform from which to study dynamics of dust particles near the sun by measuring the detailed character of the Fraunhofer structure of the zodiacal light. The suggested instrument is a wideband imaging Fabry-Perot interferometer with state of the art technology in both the optics and the detector. The instrument would function as a high-resolution imaging device providing wavelength resolution of 0.03 A over about a 20 A range. The wideband imaging capability would provide sky maps of the zodiacal light on a despun spacecraft without mechanical scanning. The Solar Probe mission would allow the velocity distribution of the dust to be mapped along most of the trajectory of the spacecraft.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 420-429
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  • 14
    Publication Date: 2006-01-16
    Description: Electron and ion plasma measurements on Solar Probe are important, especially to elucidate the role of coronal holes as sources of the solar wind and to resolve the long debated question of the importance of wave heating within 20 solar radii to the acceleration of the solar wind. Adaptable instruments are required to cover the large dynamic range of parameters between 1 AU and 4 solar radii. The baseline mission would be improved, in some respects, by the addition of a second spacecraft, following the first by a distance of several solar radii. A spinning spacecraft would be satisfactory, but not essential, for the present objectives. Attention should be paid to having the heat shield electrically conducting. An instrument for ion and electron (but no composition) measurements would have a mass of approximately 10 kg, require 8 w of power, and generate data at a maximum rate of approximately 2 kbits/sec.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 345-353
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  • 15
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    In:  CASI
    Publication Date: 2006-01-16
    Description: Some of the competing theories of solar wind acceleration and heating are reviewed, and the observations that are required to distinguish among them are discussed. In most cases what is required is measurement of plasma velocity and temperature and magnetic field, as near the sun as possible and certainly inside 20 solar radii; another critical aspect of this question is determining whether a turbulent envelope exists in this inner region, and if so, defining its properties. Plasma and magnetic observations from the proposed Solar Probe mission would thus yield a quantum jump in our understanding of the dynamics of the solar wind.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 334-344
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  • 16
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    In:  CASI
    Publication Date: 2006-01-16
    Description: A survey of all the experiments carried out over the past decade to verify theoretical predictions for the observation of solar neutrons is presented and discussed. The conclusions drawn from this discussion are: (1) the Solar Probe Mission is important in order to discover the low energy neutrons of solar origin; (2) this discovery is likely to carry very useful information about the nature, the locale, the lifetime and the mode of operation of the acceleration processes in the solar atmosphere; and (3) this information will lead to a rapid development of the science of solar meteorology and the more rapid forecasting of solar activity, on a long-term basis.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 262-270
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  • 17
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The solar probe offers a platform with particular advantages for studying solar nonthermal plasma processes via the observations of hard X-radiation from energetic electrons in the chromosphere and corona, these include (1) high sensitivity, (2) a second line of sign (in addition to the earth's) that can aid in three dimensional reconstruction of the source distribution, and, (3) the possibility of correlation with direct measurements of the nonthermal particles from the probe itself.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 132-142
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  • 18
    Publication Date: 2006-01-16
    Description: The possible role of solar probe mission in answering fundamental questions about the structure and heating of coronal loops is examined. The experimental technique consists of imaging 1-10 keV X-rays to give accurate temperature profiles of hot active regions and post-flare loops. A limitation on the interpretation of such pictures is that steroscopic reconstruction of the three dimensional arches requires many lines of sight. This kind of information can be provided only by a rapid solar flyby. In addition, the proximity to the sun will provide useful spatial resolution with compact instrumentation. The pictures thus obtained will provide crucial tests of theoretical models of coronal arches.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 111-117
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  • 19
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The spatial resolution of solar surface structure to ultimate limits with simple instrumentation. The logic is simple: a 10 cm aperture telescope at 4 solar radii resolves the equivalent of a five meter telescope in earth orbit. Given the ease of producing a diffraction limited 10 cm telescope and the difficulty of fabricating a diffraction limited 5 meter telescope, the performance of the small telescope could well be better. The telescope described complements planned solar orbiting telescopes in earth orbit and would need only a few arcs seconds of pointing.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 89-91
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  • 20
    Publication Date: 2006-01-16
    Description: The metric tensor is given for describing the dynamical effects of the sun on a solar probe and the gravitational redshift of a probe-based clock in a covariance analysis for the detectability of the solar quadrupole moment and the solar angular momentum. Unknown parameters were determined by least squares fit to the probe tracking data. A polar orbit was assumed with perihelion at 5 solar radii and with an earth-sun-probe angle of 135 deg at perihelion. Tracking was assumed to be Doppler only, with a basic uncertainity of .1 mm/sec in the radial velocity. A drag-free system which could reduce nongravitational forces below the level of 2 times 10 to the minus 12th power was found necessary to preserve this same level of accuracy. Both one way and two way Doppler were supposed in order to determine the gravitational redshift as well as the pure spacecraft dynamics.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 58-59
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  • 21
    Publication Date: 2006-01-16
    Description: Very high resolution stereoscopic images of high temperature loop structures observed at UV and X-ray wavelengths in the solar corona can be used to understand physical processes in the corona. An existing computational model is described and sample results are given to demonstrate that computational modeling of coronal structures can indeed take advantage of very high resolution images. The sample results include the run of temperature and number density along a typical loop and the variation of the differential emission measure with temperature. The integration of the differential emission measure with temperature along a column commensurate with an instrument's spatial resolution is the relevant parameter obtained from UV and X-ray observations. The effects of loop geometry and energy input are examined.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 118-131
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  • 22
    Publication Date: 2006-01-16
    Description: High resolution soft X-ray imaging from the solar probe is justified in terms of the expected scientific returns which include the determination of the temperature and density structure of a coronal loop. The advantages of the grazing incidence telescope over the multiple pinhole camera are discussed. An instrument package is described which includes a grazing incidence mirror, a thermal prefilter, a three position filter wheel and a focal plane detector baselined as an 800 by 800 back-illuminated charge coupled device. The structural assembly together with the data processing equipment would draw heavily on the designs being developed for the Solar Polar Mission.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 94-110
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  • 23
    Publication Date: 2006-01-16
    Description: A very high sensitivity rotating gravity gradiometer onboard the spacecraft is described for measuring the gravitational oblateness of the Sun during a solar probe mission. The proposed instrument would be a self-contained structure in a thermal-vacuum-magnetic shield in the shape of a cross, with a mass of 20 kg and arm length of 1.0 m and thickness of 0.1 m. The sensor inside would have a resonant frequency of 1/30 Hz, a mechanical Q of one million and would use gravitational radiation antenna technology to achieve a sensitivity of 6 x 10 to the minus 8th power Eotvos, which would provide a measurement of the solar oblateness to an accuracy of 1.5 to 6 x 10 to the minus 8th power. The gravity gradiometer will require a spinning spacecraft, so that it will not sense the spacecraft gravity fields, but the gradiometer does not need to be at the spacecraft center of mass, or even on the spacecraft spin axis. Major problem areas to be addressed are demonstration of the instrument sensitivity prior to flight and the measurement and compensation for any residual spacecraft angular rates.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 69-78
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  • 24
    Publication Date: 2006-01-16
    Description: A spacecraft going within 4 solar radii of the Sun experiences an acceleration up to .00005 g from solar radiation pressure, and significant (though smaller) accelerations from the solar wind. To obtain satisfactory information about relativistic effects and the Sun's quadrupole mass coefficient, these non-gravitational accelerations are either measured or compensated out by making the spacecraft drag free. A proof mass inside the spacecraft structure is shielded from the external forces, so that it follows a nearly ideal gravitational orbit, and a control system activates gas jets (or other translational forcers) to make the vehicle follow the mass. The problems are mechanizing the control laws and minimizing extraneous effects such as the self gravitational pull of the spacecraft. The extraneous forces can be averaged in one plane by having a spinning vehicle.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 60-68
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  • 25
    Publication Date: 2006-01-16
    Description: The use of radio tracking of a solar probe to estimate accurately the coefficient of the second zonal harmonic of the sun's gravitational field was examined. Preliminary results indicate that the coefficient can be estimated with a standard error of 10 to the minus 8th power or less, provided that the probe is equipped with a suitable drag-free system to compensate for the effects of non-gravitational accelerations. For signal paths that pass near the sun, dual-band ranging to the probe can provide the tracking accuracy needed to insure that the standard of error is equal to or less than 10 to minus 8th power. The possibility of achieving such accuracy with a single-band radio uplink and a dual-band downlink is discussed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 19-41
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  • 26
    Publication Date: 2006-01-16
    Description: Current theoretical modelling of the sun is in difficulty. Additional observations must be made to place constraints on the plethora of conjectures that have been advanced to explain the low neutrino flux and to guide solar model builders in their search to understand the deep interior of the sun. A determination of the magnitude of the solar quadrupole moment, is one such constraint; it places limits on the density, angular velocity and magnetic field distributions inside the sun.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 11-18
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  • 27
    Publication Date: 2006-01-12
    Description: The SBUV/TOMS is designed to measure the extraterrestrial ultraviolet solar irradiation and the solar ultraviolet radiation from the earth and its atmosphere. Methods to recover the ozone information from backscattered ultraviolet measurements are described. Mapping of the total ozone and 200 mb height fields is obtained.
    Keywords: SOLAR PHYSICS
    Type: The Nimbus 7 User's Guide; p 175-212
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  • 28
    Publication Date: 2006-01-12
    Description: Thermal emission and solar resonance fluorescence from the atmospheric limb are reported. Global measurements are made of radiation from the molecular species. The gas correlation spectroscopy technique based on the use of gas cells to select emission from chosen spectral lines or from particular parts of spectral lines is used. The source function and departure from the thermodynamic equilibrium between 80 and 130 kilometers associated with CO2 emission bands were investigated. The zonal wind velocity component along the line of sight is measured.
    Keywords: GEOPHYSICS
    Type: NASA. Goddard Space Flight Center The Nimbus 7 User's Guide; p 139-174
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  • 29
    Publication Date: 2006-01-12
    Description: The radiation budget of the earth on both synoptic and planetary scales by simultaneous measurement of incoming solar radiation and outgoing earth reflected (shortwave) and emitted (longwave) radiation was determined. Both fixed wide angle sampling of terrestrial fluxes at the satellite altitude, and scanned narrow-angle sampling of the radiance components, dependent on angle are used to determine outgoing radiation. Measurements of radiation are obtained in 22 different optical channels.
    Keywords: GEOPHYSICS
    Type: NASA. Goddard Space Flight Center The Nimbus 7 User's Guide; p 33-58
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  • 30
    Publication Date: 2006-01-12
    Description: Columnar spectral index information that has been extracted from a sizable volume of Voyager 1978 solar conjunction Doppler phase fluctuation data is presented. The Voyager 1978 results, when compared to similar information derived from the 1976 Helios and Viking Solar Conjunctions, lead to the following inferences: (1) there has been a significant change in the spectral index from 1976 to 1978; (2) there is continuing evidence that favors a slight (positive) correlation between the spectral index and the solar cycle; and (3) there is little or no evidence in support of a radial variation of the spectral index.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 59-65
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  • 31
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The only ballistic trajectory mode feasible for a close solar probe or for an orbit inclined approximately 90 degrees to the ecliptic is the Jupiter gravity assisted mode. A comparison of the trajectories of the Solar Polar and the Solar Probe Mission for 1983 launches is shown. The geometry of the solar encounter phase is practically the same for the 4.3 year orbit achieved by a Jupiter gravity assist and for a one year orbit. Data describing the geometry of an orbit with perihelion at 4 solar radii and aphelion at Jupiter are listed. The range of apparent directions of the solar wind if it is flowing radially outward from the Sun with a speed of either 150 or 300 km/sec is shown. The minimum sun-earth-probe angle during the solar encounter as a function of the earth-node angle and the orbital inclination is also shown. If the inclination is 60 degrees or more, the minimum SEP angle is not greatly different from the 90 degree value.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 521-534
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  • 32
    Publication Date: 2006-01-16
    Description: The effects of the transmission media - the earth's troposphere and ionosphere, and the solar wind - on precise Doppler tracking are discussed. The charged particle effects can be largely removed by dual frequency observations; however there are limitations to these corrections (besides system noise and/or finite integration times) including the effects of magnetic fields, diffraction, and differential refraction, all of which must be carefully evaluated. The earth's troposphere can contribute an error of delta f/f approximately 10 to the minus 14th power.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 450-456
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  • 33
    Publication Date: 2006-01-16
    Description: Results on the electron density spectrum, the random velocity and the mean velocity of the solar wind in the region from 5 to 100 solar radii are presented. Results are based on intensity scintillations of incoherent radio sources at different locations and different radio frequencies. The shape of the electron density irregularity spectrum is shown to be well modeled by a power law in wavenumber with a slope that abruptly steepens at higher wavenumbers. This two slope power law model is shown to have a break (defined as the wavenumber of the change of slope) that increases with decreasing distance from the Sun. The fractional random velocity is shown to be insignificant at distances of greater than 40 solar radii, but shows a steady increase with decreasing solar distance inside of 40 solar radii.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 388-396
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  • 34
    Publication Date: 2006-01-16
    Description: How the electron content between the Solar probe and the earth can be observed with a minimum of equipment and give a quantitative rationale for the use of a signal near 400 MHz to supplement the telecommunications signal is described. The emphasis is on the method of making content observations and on their value. While far from the Sun, the electron content is so low that the S-X dual-frequency system is insufficiently sensitive and a UHF system is optimum. As the probe approaches the Sun, the UHF may be disrupted by scintillation and the variations of the telecommunications signal must be used for the content measurement. By operating the suggested system in different modes as the solar distance changes, operation during the entire mission is possible.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 397-407
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  • 35
    Publication Date: 2006-01-16
    Description: Phase perturbations that occur in the following components of the one and two-way systems are considered: (1) one-way system (signal from A to B): station a oscillator - transmitter A antenna A - signal path - antenna B - receiver B station B oscillator - recording system B; (2) two-way system (signal from A to B back to A): station A oscillator - transmitter A - antenna A - signal path up - antenna B - transponder B - antenna B - signal path down - receiver A - station A oscillator - recording system A. A symmetrical one- and two-way system which can identify the place of origin of the fluctuation and quantify it so as to recover the unperturbed phase at a given moment of time by time-correlating the phase fluctuations obtained in the one- and two-way data taken at both stations is described
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 457-497
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  • 36
    Publication Date: 2006-01-16
    Description: Questions are posed and answered through discussion of gravitational wave detection with the Solar Probe. Discussed are: (1) what a gravitational wave is; (2) why wave detection is important; (3) what astrophysical information might be learned from these waves; (4) status of attempts to detect these waves; (5) why the Solar Probe is a special mission for detecting these waves; (6) how the Solar Probe's expected sensitivity compares with the strength of predicted gravitational waves; and (7) what gravity wave searchers will do after the Solar Probe.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 433-440
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  • 37
    Publication Date: 2006-01-16
    Description: A state of the art fluid continuum technique to describe the MHD transient respose of the corona below 10 solar radii during two well observed events (flares on 21 August 1973 and 5 September 1973) is reviewed. It is concluded that the computer simulation should be subjected to in situ verification of as many of its initial assumptions as possible. Its ability to provide a rational basis for physical understanding of mass ejections suggests its use as one of the tools used in the planning and analysis of such encounter missions.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 367-387
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  • 38
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    In:  CASI
    Publication Date: 2006-01-16
    Description: During the total solar eclipse of 1970, measurements of resonantly scattered Lyman-alpha radiation from the solar corona revealed a means to determine temperatures and densities in the solar corona beyond 1.5 R solar radii. A natural extension of this work is to use the Solar Probe to measure the spectral line profile of Lyman-alpha radiation backscattered toward the Sun from coronal regions between 4 R solar radii and 10 R solar radii. The backscattered profile would provide unique and quantitative determinations of the outlaw velocities of coronal material into the solar wind. Such information is of critical importance for understanding solar-wind formation and solar-terrestrial effects on the earth's climate. There is no known way to obtain this information without a Solar Probe-type mission.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 354-365
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  • 39
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    In:  CASI
    Publication Date: 2006-01-16
    Description: Scientific objectives for solar-wind investigations relevant to a Solar Probe mission are outlined and put in perspective. Information gained from the various possible measurements are also listed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 273-280
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  • 40
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    In:  CASI
    Publication Date: 2006-01-16
    Description: A brief note is summarized to show the importance of solar neutron observations for the advancement of phenomena crucial for solar physics, and to suggest the constraints which must be placed on the Solar Probe Mission for carrying out studies of this kind.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 243-261
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  • 41
    Publication Date: 2006-01-16
    Description: First and second order anisotropy measurements are proposed as a tool for studying the coronal source function and interplanetary propagation of low energy protons. Optimum orbit and attitude requirements are suggested for a three telescope system. Some limitations with regard to the lower energy limit for a feasible set-up are discussed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 234-239
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  • 42
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    In:  CASI
    Publication Date: 2006-01-16
    Description: An optical system for the solar probe is described as well as its capability for improvements in spatial resolution. A magnetograph for measuring the elementary flux tube and obtaining vector geometry field geometry offers the possibility of looking for low contrast weak structure. With the probe's orbit passing over the pole, the structure of the polar field can be directly measured. The detector plane of the system receives a telecentric image of the objective. Because there is an aperture in this focal plane that can both move and change size, polarized line profiles can be obtained at arbitrary points with variable spatial resolution. The telescope microprocessor searches for the magnetic elements and then constructs the vector field.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 155-158
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  • 43
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The merits and demerits of an approach to the Sun (more closely than about one AU) are examined. High resolution imaging (approximately 0.1 arc sec) to be obtained with the shuttle-borne solar optical telescope, will permit conclusive observations relating to the structure of the quiet solar atmosphere, sunspots, spicules, oscillations, and many other problems of solar astrophysics. Beyond this limit important unresolved structure will exist, especially in optically thin regions or in regions with strong magnetic fields. Ambiguity will remain in solar imagery because a single line of sight cannot suffice completely to untangle the vertical dimension from the two horizontal dimensions. A solar probe with a complement of solar telescopes would provide two lines of sight for solar viewing and increase knowledge of the three dimensional structure of the solar atmosphere.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 81-88
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  • 44
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    In:  CASI
    Publication Date: 2006-01-16
    Description: A covariance analysis was performed for a solar probe trajectory which encounters the sun at four solar radii. The unknown parameters in the analysis are the six initial cartesian coordinates for the probe, six initial cartesian coordinates for the earth, the astronomical unit, the solar gravitational quadrupole coefficient and two post Newtonian meters (beta, gamma). Errors in the unknown parameters were computed as a function of standard errors on the radio tracking data and on the nongravitational forces which act on the probe. Results were obtained for several tracking geometries and for several orbital inclinations to the ecliptic. The analysis shows that the principal scientific result from the radio tracking of a solar probe would be the determination of the quadrupole moment, which would place a constraint on models of the solar interior.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 42-57
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  • 45
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    In:  CASI
    Publication Date: 2006-01-16
    Description: Spectral analysis of solar wind plasma fluctuation requires knowledge of the average ground tracking system phase fluctuation spectrum. Typical ground tracking system phase fluctuation spectra are presented as deduced from two-way S-band Doppler noise measured at large Sun-Earth-Probe angles.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 125-128
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  • 46
    Publication Date: 2006-01-12
    Description: The Stratospheric Aerosol Measurement 2 (SAM 2) is used to map the concentration and optical properties of stratospheric aerosols as a function of altitude, latitude, and longitude. The vertical distribution of the stratospheric aerosols in the polar regions of both hemispheres is provided.
    Keywords: GEOPHYSICS
    Type: NASA. Goddard Space Flight Center The Nimbus 7 User's Guide; p 105-138
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  • 47
    Publication Date: 2006-01-12
    Description: A radio science data capability within the DSN Tracking System is described. This capability consists of routine provision of phase fluctuation data concurrently computed over several different time scales. This capability was used to observe phase fluctuation spectral characteristics during a rapid increase in solar wind turbulence that occurred during a July 23, 1978 track of the Voyager 1 spacecraft by Deep Space Station 11. It is suggested that the capability will prove useful in studies of variations of solar wind phase fluctuation spectral characteristics with, for instance, parameters such as the solar cycle and radial distance.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 55-58
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  • 48
    Publication Date: 2011-08-17
    Description: Exospheric neutral and electron temperatures have been estimated for the primitive upper atmosphere and ionosphere with various oxygen content in the scheme of our previous model (Shimizu and Shimazaki, 1976). The exospheric neutral temperature has been shown to be rather insensitive to the change of oxygen content, justifying our previous assumption for the temperature variation, while the exospheric electron temperature has been found to be quite sensitive to the compositional change, mainly owing to the strong dependence of electron density on the oxygen concentration.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Jan. 1
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  • 49
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    Publication Date: 2011-08-17
    Description: Computer simulations of the evolution of the earth's atmospheric composition and surface temperature have been carried out. The program took into account changes in the solar luminosity, variations in the earth's albedo, the greenhouse effect, variation in the biomass, and a variety of geochemical processes. Results indicate that prior to two billion years ago the earth had a partially reduced atmosphere, which included N2, CO2, reduced carbon compounds, some NH3, but no free H2. Surface temperatures were higher than now, due to a large greenhouse effect. When free O2 appeared the temperature fell sharply. Had earth been only slightly further from the sun, runaway glaciation would have occurred at that time. Simulations also indicate that a runaway greenhouse would have occurred early in earth's history had earth been only a few percent closer to the sun. It therefore appears that, taking into account the possibilities of either runaway glaciation or a runaway greenhouse effect, the continuously habitable zone about a solar-type star is rather narrow, extending only from roughly 0.95 to 1.01 AU.
    Keywords: GEOPHYSICS
    Type: Icarus; 33; Jan. 197
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  • 50
    Publication Date: 2011-08-17
    Description: Nitric oxide and ozone concentrations in the lower stratosphere have been measured from a high-altitude research aircraft using in situ measuring techniques. Results of several geographical surveys are presented along with predictions of two two-dimensional stratospheric models. Meridional and zonal data were obtained in June 1974 and in June, July, and August 1975. At longitudes 122-158 deg W the meridional data taken between 5 and 80 deg N latitude show an increasing NO concentration with latitude, by a factor of 4 at 21-km altitude and a less marked increase at 18 km. The minimum NO concentration at 21 km is observed at 5 deg N latitude and is about 6 x 10 to the 8th power/cu cm. Zonal data at latitudes 22-38 deg N taken from 55 to 176 deg N longitude show little variation of the NO and O3 concentrations with longitude.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Apr. 20
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  • 51
    Publication Date: 2011-08-17
    Description: The Franco-Soviet experiment package Signe 2 MP for solar and cosmic X and gamma ray observations, launched aboard a Soviet Prognoz satellite into a highly eccentric earth orbit is described. An uncollimated NaI detector 37 mm thick by 90 mm diameter, placed on the upper surface of the satellite faced the sun. A collimated lateral NaI detector 14 mm thick by 38 mm diameter also faced the sun, and a similar lateral detector faced the anti-solar direction. Data tapes reveal an intense solar flare up to energies of up to 5 MeV, with evidence for line emission at 2.23 MeV and possibly 4.4 MeV. The event observed was associated with the Mc Math Plage Region 15031, and an H-alpha flare of importance 2B. It is not yet clear what radio emission is associated with the X-ray observation.
    Keywords: SOLAR PHYSICS
    Type: NASA. Goddard Space Flight Center Gamma Ray Spectry. in Astrophys.; p 70-75
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  • 52
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    In:  Other Sources
    Publication Date: 2011-08-18
    Description: Several types of spectrometers are discussed along with their methods of operations. The open source magnetic deflection type mass spectrometer and the quadrupole mass spectrometer are described in detail. The calibration and mounting procedures used for satellite-borne mass spectrometers were reviewed.
    Keywords: GEOPHYSICS
    Type: Alabama Univ. UAH(NASA Workshop on the Use of a Tethered Satellite System; p 120-129
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  • 53
    Publication Date: 2011-08-18
    Description: The Tethered Satellite System in combination with in situ atomic and molecular resonance fluorescence techniques can treat the problem of simultaneously determining the absolute density of atomic and molecular species known to control the photochemical structure of the upper atmosphere. Two familities of reactants which can be treated by these techniques are the nitrogen oxygen family and the hydrogen oxygen family.
    Keywords: GEOPHYSICS
    Type: Alabama Univ. UAH(NASA Workshop on the Use of a Tethered Satellite System; p 111-118
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  • 54
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    In:  Other Sources
    Publication Date: 2011-08-18
    Description: The broad-scale magnetic anomalies that appear in regional complications of aeromagnetic data, and in regional and global maps are discussed. Satellite data can be of value in defining such anomalies and invaluable, especially when utilized with airborne data, in their interpretation. The reduction and interpretation of satellite magnetometer data differ significantly from the standard techniques that are routinely applied to conventional measurements. The reduction of the data is discussed and its morphology is detailed. Interpretational techniques that are applicable are presented.
    Keywords: GEOPHYSICS
    Type: Alabama Univ. UAH(NASA Workshop on the Use of a Tethered Satellite System; p 59-91
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  • 55
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    Publication Date: 2011-08-18
    Description: A Chemical Release Module to be carried into orbit by the shuttle is described. The module would release chemicals from orbiting satellites in order understand processes within the Earth's magnetosphere, atmosphere and ionosphere. A large number of potential experiments are identified, ranging from introducing traceable material into the solar wind in order to study its transport to and within the magnetosphere, to injecting material into the outer magnetosphere to simulate the precipitation of trapped charged particles, to the release of material at lower altitudes to create waves both mechanical and electromagnetic.
    Keywords: GEOPHYSICS
    Type: Alabama Univ. UAH(NASA Workshop on the Use of a Tethered Satellite System; p 135-150
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  • 56
    Publication Date: 2011-08-18
    Description: The calibration of apparatus like mass spectrometers under free molecular conditions and the design and execution of relevant calibration experiments in the transition regime in low density wind tunnels is addressed. Potential access to the tethered satellite for beam instrumentation is discussed and would involve aerodynamic design input on the satellite, both as to preferred shape for the experiments and aerodynamic control for up-stream pointing. Aerodynamic design for the purpose of stabilization and pointing is also discussed.
    Keywords: GEOPHYSICS
    Type: Alabama Univ. UAH(NASA Workshop on the Use of a Tethered Satellite System; p 106-110
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  • 57
    Publication Date: 2011-08-18
    Description: A detailed investigation of the Earth's gravity field is needed for application to modern solid earth and oceanic investigations. The use of gravity gradiometers presents a technique to measure the intermediate wavelength components of the gravity field. One configuration of a gradiometer involves a tethered pair of masses orbiting the Earth and stabilized by vertical gravity gradient of the earth. A mesurement of the tension in such a system, called the DUMBBELL system is described. It allows the determination of the vertical gradient of the anomalous component of the Earth's gravtiy field. Preliminary analysis of the dynamics, mechanization, expected signal levels and noise environment indicates that the Dumbbell system is feasible.
    Keywords: GEOPHYSICS
    Type: Alabama Univ. UAH(NASA Workshop on the Use of a Tethered Satellite System; p 33-58
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  • 58
    Publication Date: 2011-08-17
    Description: The effects of chlorine perturbations on both the temperature and the ozone distribution in the stratosphere have been studied using a simplified radiative-photochemical model. The model solves the hydrostatic equation for total density in a self-consistent manner as the temperature is changed. Radiative coupling is found to have a significant effect on both the thermal structure and the ozone distribution, particularly in the 35-50-km region. By increasing the ClX mixing ratio by 5.0 ppbv, the temperature in this region is decreased by 5 to 10 K with a slight increase below 30 km. The local ozone depletion around 40 km due to added ClX is smaller compared with the estimate made by keeping the temperature fixed to the ambient condition. However, the integrated effect of radiative coupling is to increase the calculated column ozone depletion by 15% to 25% in this model.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Mar. 197
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  • 59
    Publication Date: 2011-08-17
    Description: Ion composition data from the OGO-6 satellite are used to develop an empirical model of the H(+) signature in the equatorial anomaly. The empirical model is an attempt to represent the generally repeatable details of the satellite data by a parameterized numerical model accounting for such variables as the altitude, local time and longitude of the observations. Although the resulting model is in general agreement with past findings on the variability of the equatorial anomaly phenomenon, there appears to be a complexity of short-term or narrowly localized variations which cannot be adequately understood on the basis of data from a single satellite.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics and Space Physics; 16; May 1978
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  • 60
    Publication Date: 2011-08-17
    Description: Nitric oxide has been measured in situ between 38.4 and 29.8 km by a new technique, photoionization mass spectrometry. Data indicate a peak mixing ratio of 5.7 plus or minus 0.35 ppbv at 37.5 km and only 0.2 plus or minus 0.2 ppbv at 32.8 km with a sharp gradient in concentration between 33 and 34 km. Simultaneous in-situ measurements of the ozone concentration show no significant feature at that altitude. The rapid decrease in mixing ratio is not predicted by current theory.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Jan. 197
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  • 61
    Publication Date: 2011-08-17
    Description: The experiment to detect gravitational waves in ultraprecise two-way Doppler data is described, as are the anticipated requirements for the Deep Space Network, the spacecraft, and the data processing system. The special feature which allows the usage of ultraprecise Doppler data for the possible detection of gravitational waves is a unique three-pulse signature which is a function of the spacecraft, earth, and gravitational wave propagation direction geometry. The pulses (fractional frequency shifts) result from effects which are conveniently described as follows: Clock speed-up (earth only effect) and buffeting (equal earth and spacecraft effect).
    Keywords: GEOPHYSICS
    Type: The Deep Space Network; p 100-108
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  • 62
    Publication Date: 2011-08-17
    Description: Isolated ionospheric irregularities produce oscillating diffraction patterns on the ground. In the present study typical physical properties such as density, size, etc. of these irregularities are estimated on the basis of diffraction pattern characteristics. These properties agree well with those of meteor trail ionization and it has been found that most of these oscillating irregularities occur on meteor shower days. It is therefore suggested that the oscillating irregularities are caused by meteor showers.
    Keywords: GEOPHYSICS
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  • 63
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    Publication Date: 2011-08-17
    Description: In view of the importance of charge exchange decay as a loss mechanism for magnetospheric ions, the paper summarizes the latest and best measurements of the physical quantities involved in the calculation of the charge exchange lifetime of the mirroring ions. The normalized atomic hydrogen distribution is presented as a function of radial distance on the basis of the Chamberlain model for a range of exobase temperatures and for various combinations of satellite particles. Cross section measurements for various ions in the energy range 1 keV to 200 keV are summarized in the form of normalized charge exchange lifetimes. The equatorial lifetimes can be determined for any of these ions at a specific energy and L-value.
    Keywords: GEOPHYSICS
    Type: Space Science Reviews; 22; Aug. 197
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  • 64
    Publication Date: 2011-08-17
    Description: The results of Faraday rotation measurements made at Ootacamund during ATS-6 phase II are presented. For summer and equinoctial months, even though no clear noon bite-out is observed in the variation of Faraday a decrease is observed in the rate of increase of rotation around 0900-1000 hours LT. This is attributed to the 'fountain effect' which is responsible for the noontime bite-out in F2-region peak electron density.
    Keywords: GEOPHYSICS
    Type: Indian Journal of Radio and Space Physics; 7; June 197
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  • 65
    Publication Date: 2011-08-17
    Description: A numerical model of total electron content (TEC) at low latitudes has been constructed from the Faraday rotation data recorded at a number of locations in India during the period Oct. 1975-July 1976 when the geostationary satellite ATS-6 was located at 35 deg E. In all, 36 coefficients for each season are required to represent the model. The model can be used for satellite tracking systems in estimating quickly the range, range rate and angular refraction errors. The present model is an improvement over the previously constructed model based on orbiting satellite data.
    Keywords: GEOPHYSICS
    Type: Indian Journal of Radio and Space Physics; 7; June 197
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  • 66
    Publication Date: 2011-08-17
    Description: Line profiles of optically thin extreme-ultraviolet emission lines observed in a quiet sun region at positions within and above the white-light limb with the NRL slit spectrograph (S082-B) on Skylab are discussed. Absolute line intensities and full widths at half-maximum are presented for lines formed over the temperature range from about 10,000 to 22,000 K. The line intensities are compared with the predictions of simple atmospheric models consisting of a spicule component and a thin spherically symmetric or network models, but can be explained by assuming that the emission arises from spicule-like inhomogeneities. Random mass-motion velocities are calculated. The velocity increases with increasing temperature of line formation. Near the limb and above about 4000 K the calculated velocity is consistent with the predictions of a constant acoustic flux passing through the transition zone. For the ions formed at temperatures not less than about 63,000 K, the velocity is found to increase with increasing height above the white-light limb.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 67
    Publication Date: 2011-08-17
    Description: A first-order mass- and energy-balance model is developed for steady-state EUV 'coronal rain' loops that are not associated with postflare events and are often seen over sunspot umbrae. The model disregards variations in a loop's thermodynamic and magnetic properties along magnetic-field lines and yields average properties of the resonant absorption sheath, the boundary layer, and the loop's interior. Both irreversible heating by Alfvenic surface waves and energy transport via induced boundary-layer convection are taken into account in the analysis. Results that include predictions of the temperatures of the sheath and the boundary-layer plasma, the temperature of the interior plasma, the radiative output of the loop, and the filling factor associated with this radiation are given in terms of the period and velocity amplitude of the relevant surface wave as well as various parameters that characterize a typical 'coronal rain' loop. These results are shown to be consistent with the observed minimum and maximum temperatures as well as the radiative output of typical 'coronal rain' loops.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 68
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    Publication Date: 2011-08-17
    Description: A viscoelastic stiffness model of seismicity is developed by introducing a viscoelastic element into the stiffness model for fault dynamics. The introduction of this element permits modeling of transient anelastic deformations in response to stress loading and relaxation and provides a mechanism for partial stress recovery following an earthquake. As a consequence, several phenomena not present in elastic stiffness theory emerge. These include postseismic creep, foreshocks, and aftershocks. Numerical simulations of fault motion also reveal episodes of stable sliding, tertiary creep preceeding earthquakes, and long-term aseismic creep.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Nov. 10
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  • 69
    Publication Date: 2011-08-17
    Description: Results are presented for a comprehensive survey of thermal ion composition and electron temperature (Te) variations in the southern high-latitude winter F region near 300-km altitude. The data are obtained from the Atmosphere Explorer (AE-C) satellite during a magnetically quiet period centered on the June 1976 solstice. Prominent ionospheric features, including the nightside main trough, a high-latitude ionization hole, and the dayside auroral zone-cusp region, are characterized in terms of composition and Te variations. The structures under study are qualitatively interpreted in terms of known processes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Oct. 1
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  • 70
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    Publication Date: 2011-08-17
    Description: Ion mass-spectrometer measurements on Atmosphere Explorer C orbits from December 1974 to December 1976 were surveyed poleward of + or - 30 deg for instances in which the Fe(+) number density exceeded the spectrometer threshold sensitivity of 30/cu cm. The occurrences of Fe(+) within the altitude range covered by the orbit, 220 to 320 km, revealed a distinct pattern apparently associated with regions of upward plasma transport. At night a band of such events occurred between 50 and 60 deg invariant latitude, which typically corresponded to the location of the main ionospheric trough. In this region large upward ion drifts due to the drag of an equatorward-blowing neutral wind are expected. The Fe(+) band extends past 0600 MLT to about 1100 MLT during the summer, but is not observed in the afternoon. The dayside distributions possibly result from the upward drifts of F-region ions detected by backscatter techniques after dawn during summer. At higher latitudes patches of Fe(+) were detected in regions where strong plasma drifts often prevail and hence where poleward E x B drift motions and atmospheric expansion through Joule heating can lift the ions upwards.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Sept
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  • 71
    Publication Date: 2011-08-17
    Description: The profiles of spectral lines in the 1100-2000-A range emitted by transition-zone ions in regions of solar activity are discussed. The data were recorded by the NRL spectrograph on Skylab. At the spatial resolution of the Skylab spectrograph (2 x 60 arcsec), it is shown that the line profiles result from the superposed emission of a number of physically distinct regions at different electron densities and with different mass motions. Although high densities are found for some surgelike phenomena at transition-zone temperatures, the densities can also be comparable to normal active-region densities. Line profiles, as well as spectral line intensities, must be considered if meaningful theoretical models of dynamic activity in the transition zone are to be constructed.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 69; 1, Se; Sept
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  • 72
    Publication Date: 2011-08-17
    Description: The electron density data returned by the polar orbiting satellites Ariel 3 and Ariel 4 revealed that the midlatitude trough is one of the distinct large-scale features of the ionosphere at about 550 km. Recent work (e.g., Tulunay and Grebowsky, 1975) on the data included the investigation of the temporal development of the latitudinal position of the midlatitude electron density trough at dawn and dusk during the large magnetic storms of May 1967 and May 1972. Model calculations which assumed that the equatorial convection E-field varies in step with the Kp index reproduced on the average the observed behavior. In the present paper, trough observations made at noon and midnight during the period, 12-21 December 1971 which encompassed a relatively large magnetic storm are discussed. In this context, model calculations have been employed as a guide of average approximations of the actual situation in predicting the plasmapause location. It is also shown that the trough observed on the noon passes is not generally plasmapause-related as the nightside troughs are expected to be.
    Keywords: GEOPHYSICS
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  • 73
    Publication Date: 2011-08-17
    Description: The relative abundances of 1.5-23 MeV per nucleon ions in corotating nucleon streams are compared with ion abundances in particle events associated with solar flares and with solar and solar wind abundances. He/O and C/O ratios are found to be a factor of the order 2-3 greater in corotating streams than in flare-associated events. The distribution of H/He ratios in corotating streams is found to be much narrower and of lower average value than in flare-associated events. H/He in corotating energetic particle streams compares favorably in both lack of variability and numerical value with H/He in high-speed solar wind plasma streams. The lack of variability suggests that the source population for the corotating energetic particles is the solar wind, a suggestion consistent with acceleration of the corotating particles in interplanetary space.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 224
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  • 74
    Publication Date: 2011-08-17
    Description: A set of 22 simple impulsive solar flares, identified in the OSO 5 hard X-ray data, has been analyzed together with coincident microwave and meter-wave radio observations. The rise times and fall times of the X-ray bursts are found to be highly correlated and effectively equal, strongly suggesting a flare-energizing mechanism that is reversible. The good time resolution available for these observations reveals that the microwave emission is influenced by an additional process, evident in the tendency of the microwave emission to peak later and decay more slowly than the symmetric X-ray bursts. Meter-wave emission is observed in coincidence with five events which also show strong time correlation between the X-ray and microwave burst structure. This meter-wave emission is characterized by U-burst radiation, indicating confinement of the flare source. The relationship found between the X-ray burst duration and the calculated flare diameter, together with the thermal character of the X-ray spectra, gives additional support to the hypothesis that the impulsive component is driven by adiabatic compression and expansion of a magnetically confined plasma which is the common primary source of both X-ray and microwave emission.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 223
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  • 75
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    Publication Date: 2011-08-17
    Description: The accuracy of two recent geopotential models, GEM 7 and GEM 8, is evaluated and is found to be about 4.3 m with respect to the global geoid surface for GEM 7 and 3.9 m for GEM 8. The accuracies are root mean square values obtained by the use of 400 coefficients for GEM 7 and 706 coefficients for GEM 8. Independent observations used in the evaluation include 159 lumped coefficients from 35 resonant orbits, two sets of fields derived from optical-only and laser-only data, sets of zonal and resonant coefficients, and geoid undulations. The ratio of estimated commission to formal error in GEM 7 and GEM 8 ranges from 2 to 5. Several other recent geopotential models are examined.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 26; Dec. 197
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  • 76
    Publication Date: 2011-08-17
    Description: Laser range observations taken on the near-earth satellites of Lageos (a = 1.92 e.r.), Starlette (a = 1.15 e.r.), BE-C (a = 1.18 e.r.), and Geos-3 (a = 1.13 e.r.) have been combined to determine an improved value of the geocentric gravitational constant (GM). The value of GM is 398600.61 cu km/sec per sec, based upon a speed of light, c, of 299792.5 km/sec. Using the IAG-adopted value of c equalling 299792.458 km/sec scales GM to 398600.44 cu km/sec per sec. The uncertainty in this value is assessed to be plus or minus 0.02 cu km/sec per sec. Determinations of GM from the data taken on these four satellites individually show variations of only .04 cu km/sec per sec from the combined result. The Lageos information dominated the combined solution, and gave the most consistent results in its data subset solutions. The value obtained for GM from near-earth laser ranging compares quite favorably with the most recent results of the lunar laser and interplanetary experiments.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Dec. 197
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  • 77
    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 78
    Publication Date: 2011-08-17
    Description: A large number of electrochemical concentration cell (ECC) ozonesondes were calibrated in relation to a UV photometric absorption ozone instrument prior to using the ozonesondes in atmospheric soundings. The two methods of measuring ozone were in reasonable agreement on the average, but there was considerable variation from one ozonesonde to another. Averaging the individual linear regressions gives an ECC ozone concentration equal to 0 + or - 8 nbar plus (0.96 + or - 0.10) times the concentration determined with the UV instrument, where uncertainties represent 90% confidence limits. Applying individual calibration corrections to atmospheric sounding data reduced the mean difference between Dobson spectrophotometric measurements of total ozone overburdens and corresponding values obtained from ozonesonde data from -8.5 + or - 8.2 to -1.4 + or - 7.3% for a series of measurements carried out in 1977. Corresponding uncorrected and corrected differences averaged 3.2 + or - 9.7 and 1.9 + or - 10.6%, respectively, for soundings carried out in 1976.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Nov. 20
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  • 79
    Publication Date: 2011-08-17
    Description: Estimates of the ozone total columnar content, derived from Nimbus IV IRIS data, have been analyzed to estimate monthly averages of the total global atmospheric ozone. Over a 9-month interval, the variation in this monthly average is approximately an order of magnitude greater than its associated uncertainty, and has characteristics in common with variations in the 10.7 cm solar flux, the Zurich sunspot number, and the total solar Lyman alpha flux. The highest correlation, 0.94, exists between the variation in the total Lyman alpha flux and the variation in the estimated total atmospheric ozone.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Nov. 197
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  • 80
    Publication Date: 2011-08-17
    Description: A unifying description is provided of some important dynamic properties of the upper atmosphere in composition and temperature characteristic of a variety of phenomena, including diurnal and seasonal tides, magnetic storms, and momentum coupling with the magnetosphere. A theoretical multiconstituent model is used which can link the large-scale variations of composition and temperature to the dynamics and energetics of the thermosphere. Global mean properties of the thermosphere are reviewed, and an attempt is made to convey some understanding of the dynamic properties of energy and diffusive mass transport in the thermosphere. Attention is given to sources of energy for the thermosphere, the transport processes involved in the solar diurnal tide of the thermosphere, energy and particle sources for the annual tide, feedback from composition changes to wind-field and temperature variations, energy deposition in the thermosphere during magnetic storms and substorms, and momentum source signatures in the thermosphere.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics and Space Physics; 16; Nov. 197
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  • 81
    Publication Date: 2011-08-17
    Description: It is noted that recent measurements of large values of the rate coefficient for the reaction NO + HO2 yields NO2 + OH lead to model predictions of excessive amounts of stratospheric ozone. This letter shows that a recent measurement of the rate coefficient (k2) for the reaction HO2 + O3 yields OH + 2O2 largely resolves these problems of excessive stratospheric ozone in models. A two-dimensional model of stratospheric trace constituents is used to calculate the concentrations of 35 constituents; the results are compared with experimental measurements of ozone column densities. It is found that the model predictions of excess ozone abundances diminish significantly when the measured value of k2 is employed.
    Keywords: GEOPHYSICS
    Type: Nature; 275; Oct. 12
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  • 82
    Publication Date: 2011-08-17
    Description: High time-resolution data from the magnetic field, plasma, energetic particle, and VLF wave experiments performed aboard Imp 6 in a study of the distant dayside cusp during substorms are described. The cusp was studied when its location was slightly equatorward of its normal location and the geomagnetic dipole was tilted in the appropriate direction. The data support both reconnection and diffusion as methods of particle entry to the magnetosphere. The evidence (1) indicates an acceleration process to explain enhancements of 400 to 600-km/sec protons above their magnetosheath intensities, and (2) suggests convection of field lines over the polar cap as a means of explaining the lack of low-energy protons near the low-latitude boundary of the cusp. Magnetic field fluctuations, a perturbation vector, ion cyclotron waves, and an abrupt change in the intensity of both whistler waves and electrostatic waves are characterized.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Sept. 1
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  • 83
    Publication Date: 2011-08-17
    Description: The paper examines sources of magnetic fields in recurrent streams observed by the Imp 8 and Heos spacecraft at 1 AU and by Mariner 10 en route to Mercury between October 31, 1973 and February 9, 1974, during Carrington rotations 1607-1610. Although most fields and plasmas at 1 AU were related to coronal holes and the magnetic field lines were open in those holes, some of the magnetic fields and plasmas at 1 AU were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines may be more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes, certain photospheric magnetic fields, and the coronal footprints of the sector boundaries on the source surface are characterized.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Sept. 1
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  • 84
    facet.materialart.
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    In:  Other Sources
    Publication Date: 2011-08-17
    Description: Large scale regions of depleted equatorial ionospheric plasma, called equatorial bubbles, are investigated using topside sounder data. The sounder's unique remote measuring capability enables the magnetic field-aligned nature of the bubbles to be investigated. A search of all available Alouette 2 and ISIS 1 ionograms during nighttime perigee passes near the magnetic equator has revealed a variety of echo signatures associated with bubbles. In addition to a sudden drop in electron density, these signatures usually include in situ spread F and ducted traces. The ducted traces have been used to determine the electron density distribution and to infer changes in ion composition along the magnetic field line within the duct associated with the bubble. In some cases it can be determined that the bubble is asymmetric with respect to the magnetic equator. Even though such features require 3 dimensional models for their explanation, the great field-aligned extent of the bubbles (relative to their cross section) suggests that current theories, which ignore variations along the magnetic field, are still applicable.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Sept
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  • 85
    Publication Date: 2011-08-17
    Description: A three-dimensional model has been developed to describe momentum coupling between high-latitude electric fields, neutral winds, temperature, and composition. The Hall drag is found to be the main source for atmospheric winds and the small divergence component of winds is due to the Pedersen drag and the Hall drag. Adiabatic heat transfer is responsible for the back pressure which damps the divergence field and for the reversal in circulation of the divergence field at higher altitudes. Back pressure causes a decrease in total wind velocity of about 10% at exospheric heights and by a factor of about 2 at 120 km. The wind field with the pressure feedback may be simulated by neglecting pressure variations and the Coriolis force. Density variations of Ar, N2, O, and He, induced by the momentum source, are in phase above 120 km and out of phase with the temperature amplitude above 150 km. The electrostatic field momentum source is ineffective for directly inducing density and temperature variations in the upper thermosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; July 1
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  • 86
    Publication Date: 2011-08-17
    Description: Measurements of neutral composition and temperature obtained between December 6, 1975, and September 17, 1976, with instruments aboard the near-equatorial AE-E satellite are analyzed to determine the diurnal variations at altitudes from 145 to 295 km. The general trends, including the shift in oxygen phase from afternoon at high altitudes to morning at low altitudes, are reproduced by circulation theories. The oxygen and helium variations show small departures from diffusive equilibrium below 200 km that are consistent with wind-induced diffusion and provide the first direct evidence of transport processes in the diurnal tide of the thermosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; July 1
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  • 87
    Publication Date: 2011-08-17
    Description: Continuing a study of heliocentric dependence of EUV emission line intensities observed by the Goddard OSO-7 spectroheliograph in 1972, the variation of lines of the ions Fe XII, Fe XI, Fe XV, Si X and S XII, Si IX and S XI is compared with the results of individual calculations for these ions, including theoretical intensities presented for Fe XII and Fe XI. Agreement is found to be good for Fe XII and reasonable for some of the lines of the other ions which in general are weaker in intensity. Several apparent anomalies are found however which may be due to unknown line components near the wavelengths observed.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 67; 1, Ju; June 197
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  • 88
    Publication Date: 2011-08-17
    Description: Gaseous emissions from a spacecraft modify the orbital environment and degrade the observations of distant radiation sources. These emissions also provide contamination fluxes induced by self-scattering and scattering with ambient particles. Experiments were carried out on the orbiting Atmosphere Explorer D satellite (AE-D) to verify the calculated return fluxes of a neon source. Known rates of neon were emitted in the direction of the velocity vector on command from the MRMU (molecular return measurement unit). At 250 km the neutral mass spectrometer indicated a total neon return flux of 0.0246 times the emitted flux. The calculated fraction was 0.0123, including 0.00914 for the ambient scatter and 0.00354 for the altitude-independent self-scatter. The pressure gages indicated pressures less than 7 microtorr at altitudes from 161 to 210 km. The maximum pressure for the 161-km orbit was calculated as 0.74 microtorr.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Jan. 1
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  • 89
    Publication Date: 2011-08-17
    Description: A demonstration is presented that a finite-amplitude circularly-polarized Alfven wave is generally unstable in a MHD fluid. The wave decays by a four-wave coupling process in which the daughter waves are forward propagating random density and magnetic fluctuations and a backward-propagating magnetic wave. For parameters typical of the solar corona and the solar wind (thermal to magnetic energy density ratios between 0.1 and 1, and values between 0.1 and 0.9 for the ratio of magnetic energy density of the initial Alfven wave to that of the background magnetic field), large decay rates are found.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 219
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  • 90
    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 219
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  • 91
    Publication Date: 2011-08-17
    Description: Taking into account heat conduction in the analysis of electron temperature data acquired by the AE-C satellite during the daytime at middle latitudes is shown to bring theoretical electron temperature profiles in good agreement with experimental ones. Middle latitude passes were chosen because in this region the horizontal electron temperature gradient is negligible and the height variation can be approximated by the satellite data. Inclusion of heat conduction is shown to have little effect on low-latitude data.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Apr. 197
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  • 92
    Publication Date: 2011-08-17
    Description: Observational evidence suggests the presence of solar UV variability in the spectral range 0.175-0.310 micron during the 11-year solar cycle. The present paper reports the results of a study using a steady-state 1-D radiative-convective-photochemical model conducted to determine the response of stratospheric temperatures and O3, O(1D), O(3P), and N2O constituent distributions to UV variability. Results show that concentrations of constituents and the thermal structure may be altered significantly for the altitude interval between 20 and 55 km.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Apr. 197
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  • 93
    Publication Date: 2011-08-17
    Description: The AE-C satellite measurements of electron temperature and ion concentration are used to construct a model of the relationship between these parameters and its variation with altitude in the daytime, nonauroral ionosphere. The major features of the model are that electron temperature is independent of ion concentration at altitudes below 200 km and that electron temperature varies inversely with ion concentration above perhaps 250 km. This behavior is qualitatively consistent with current theoretical models of ionospheric heating and cooling.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 5; Apr. 197
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  • 94
    Publication Date: 2011-08-17
    Description: Consideration is given to the influence on ozone of an increased carbon dioxide concentration, for which a measurable growth has been observed in the recent past. Increased carbon dioxide can indirectly affect ozone by perturbing atmospheric temperatures, which will alter ozone production, whose rate displays a fairly strong temperature dependence. This paper presents one-dimensional model results for the steady state ozone behavior when the CO2 concentration is twice its ambient level; the results account for coupling between chemistry and temperature. When the CO2 level doubled, the total ozone burden increased in relation to the ambient burden by 1.2-2.5%, depending on the vertical diffusion coefficient used. Above 30 km, ozone concentrations were larger than the ambient values, a maximum increase of 16% being reached at 43 km. In this region the relative variations were insensitive to the choice of diffusion coefficient. Below 30 km, ozone concentrations were smaller than the unperturbed values and were sensitive to the vertical diffusion profile in this region (10-30 km).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Mar. 20
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  • 95
    Publication Date: 2011-08-17
    Description: Satellite drag data, in situ mass spectrometer data, Fabry Perot interferometer data, and incoherent scatter data were used to produce models of the concentration of atomic oxygen and molecular nitrogen in the thermosphere and of the exospheric temperature. Incoherent scatter data from two stations near 45 deg N were used. The three techniques provide similar patterns for the annual variations of the atomic oxygen concentration at 400 km, and the mean annual temperatures are within 20 K of each other for five of the six models involved. Four of the models are in good agreement concerning the annual temperature variation. There is fair agreement between incoherent scatter models and mass spectrometer models for the N2 concentrations at 400 km but disagreement between these models and the satellite drag model. It is shown that most disagreements can be resolved by changing both the vertical temperature profile and the lower-thermosphere oxygen concentration in the direction indicated by previous incoherent scatter measurements.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Mar. 1
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  • 96
    Publication Date: 2011-08-17
    Description: An investigation is made of the adiabatic particle motion occurring in an almost drift-free magnetic field. The dependence of the mean drift velocity on the equatorial pitch angle and the variation of the local drift velocity along the trajectories is studied. The fields considered are two-dimensional and resemble the geomagnetic tail. Derivations are presented for instantaneous and average drift velocities, bounce times, longitudinal invariants, and approximations to the adiabatic Hamiltonian. As expected, the mean drift velocity is significantly smaller than the instantaneous drift velocities found at typical points on the trajectory. The slow drift indicates that particles advance in the dawn-dusk direction rather slowly in the plasma sheet of the magnetospheric tail.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Mar. 1
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  • 97
    Publication Date: 2011-08-17
    Description: The latitudinal boundaries of stationary fast solar wind streams emerging from equatorward extensions of the sun's polar coronal holes are studied. Simultaneous data from the Helios 1 and Imp spacecraft at different heliographic latitudes are compared. The measured latitudinal speed gradient of 30 km/s/deg shows that large angular speed gradients occur at the leading edges of fast streams and also with respect to latitude. The data indicate that longitudinal speed gradients are steeper near 0.3 AU than at 1.0 AU. Generally, regions with large angular speed gradients are observed to separate fast streams from the surrounding slower plasma. This suggests the existence of mechanisms which diminish longitudinal speed gradients as the plasma travels toward 1.0 AU. It also seems that the distribution of solar wind speeds on a near-sun spherical surface has large mesalike high-speed regions. Comparisons of Helios 1 and Imp data with corona observations supports the hypothesis that high-speed solar wind streams emerge from coronal holes.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Mar. 1
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  • 98
    facet.materialart.
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    In:  Other Sources
    Publication Date: 2011-08-17
    Description: The nitric oxide density was measured from 110 to 300 km by a rocket photometer during the day. The small measured peak density, about 6.2 x 10 to the 6th/cu cm at 111 km, can probably be attributed to the period of very low solar magnetic activity preceding the rocket flight. This experiment was coordinated with a similar measurement made by the Ultraviolet Nitric Oxide Experiment aboard the Atmosphere Explorer C satellite; the measurements are in good agreement. The altitude resolution (less than 1 km) and sensitivity (1600 counts/R/s) greatly exceed those of previous measurements. Comparison to a model shows agreement above 200 km but less nitric oxide and more structure below that.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 83; Feb. 1
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  • 99
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    In:  Other Sources
    Publication Date: 2011-08-17
    Description: Three maps are presented of f(0) sporadic-E greater than 7 MHz for temperate zones. During map preparation it was assumed that: (1) the geographical area would be between plus and minus 60 deg geomagnetic latitude, excluding the equatorial zone, (2) the maps would be for f(0) sporadic-E greater than 7 MHz, (3) sunspot cycle variation would be ignored, (4) one map would represent the peak sporadic-E period with a discontinuity at the geographic equator, (5) one map would represent non-peak periods with a discontinuity at the geographic equator, (6) one map would represent all twelve months with no equatorial discontinuity, and (7) previously determined coefficients for median and upper decile f(0) sporadic-E would be extrapolated to 7 MHz.
    Keywords: GEOPHYSICS
    Type: Radio Science; 13; May-June
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  • 100
    Publication Date: 2011-08-17
    Description: Geological data are used as cosmological determinants in a study of the temperature of the early earth (2.3 to 4.5 billion years ago). It is known that the energy output of the sun during that period was on the order of 30-40% lower than at present, and deduced that the mean temperature of the earth should have fallen to as low as 245 K, i.e., below the freezing point of seawater. Strong evidence exists, however, to indicate that algae (therefore liquid water) was present. To reconcile the discrepancies, a model is proposed whereby terrestrial G and M vary. It is further noted that atmosphere H2 may be a better agent than NH3 for producing a greenhouse effect.
    Keywords: GEOPHYSICS
    Type: Astronomy and Astrophysics; 65; 3, Ma; May 1978
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