Statistical characteristics of the meteor radio echo in the epoch of the 1963 Geminids
Statistical characteristics of meteor radio echo in epoch of 1963 Geminids
METEOR↗
SEARCH · Engineering Papers
Results for “radar observations”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Sensing of meteorological variables by laser probe techniques Semiannual report, 1 Aug. 1966 - 31 Jan. 1967
Optical radar sensing of meteorological variables in atmosphere and ionosphere
RADAR OBSERVATION↗
Space density of radio meteors
Space-density distribution of dust in solar system observed from radar meteor orbits
INTERPLANETARY DUST↗
Cislunar electron content as determined by radar group delay measurements.
Radar measurement of differential group delay to moon, showing large differences in total cislunar electron content above 1000 km in solar and antisolar directions
RADAR OBSERVATION↗
Radar studies of Venus.
Radar studies of Venus noting values for rotation vector, latitudes and longitudes of several features and Earth influence on Venus rotation
VENUS↗
Laser backscatter correlation with turbulent regions of the atmosphere.
Ground based optical radar backscatter observations of local aerosol concentrations correlated with clear air turbulence experienced by jet aircraft
Lawrence, J. D., Jr.↗
Radioray investigations contribute to the treasure of human knowledge
Respective roles of ground, optical, and radar astronomy observations for Mars and Moon studies
Troitskiy, V.↗
Probing the clear atmosphere with high power, high resolution radars.
Radar echoes observed from clear atmosphere, discussing scattering mechanisms of thin stable inversions, convective thermals, Benard convection cells, breaking gravity waves, etc
Hardy, K. R.↗
Quarterly report of the Haystack Observatory, 1 January - 31 March 1971
Radar astronomy observations on quasars, lunar craters, and Venus topography
Source record↗
A global empirical model of thermospheric composition based on OGO-6 mass spectrometer measurements.
A global empirical model for magnetically quiet conditions has been developed to describe longitudinally averaged OGO-6 N2, O, and He densities (in the altitude range 400 to 600 km) by means of an expansion into spherical harmonics. The annual asymmetric component in N2 density corresponds to an increase of about 400 K between winter and summer poles, which is about a factor of three greater than in the Jacchia model. However, the corresponding oxygen component at satellite altitudes reflects an increase between winter and summer comparable to that in the Jacchia model; this implies that at 120 km atomic oxygen increases by more than a factor of two between summer and winter poles. The amplitude of the symmetric semiannual component in N2 is larger at the poles than the equator. At the poles, the N2 variation corresponds to a temperature decrease of about 70 K from mid-April to mid-July. At low latitudes, the daily temperature maximum occurs close to 16 hours local time, nearly in agreement with radar backscatter observations.
Hedin, A. E.↗
Simultaneous in situ electron temperature comparison of Alouette 2 probe and plasma resonance data.
The electron temperatures deduced from Alouette 2 diffuse resonance observations are compared with the temperatures obtained from the Alouette 2 cylindrical electrostatic probe experiment using data from five mid- to high-latitude telemetry stations. The probe temperature is consistently higher than the diffuse resonance temperature. The average difference ranged from approximately 10% to 40%, the lower values occurring at the lowest altitudes sampled (near 500 km) and at high latitudes (dip latitude greater than 55 deg) and the larger values occurring at higher altitudes and lower latitudes. The discrepancy appears to be of geophysical origin, since it is dependent on the location of the data sample. These observations support the view that the discrepancy often observed between radar backscatter and probe electron temperature is of geophysical origin.
Benson, R. F.↗
Collection and processing of data from a phase-coherent meteor radar
An analysis of the measurement accuracy requirement of a high resolution meteor radar for observing short period, atmospheric waves is presented, and a system which satisfies the requirements is described. A medium scale, real time computer is programmed to perform all echo recognition and coordinate measurement functions. The measurement algorithms are exercised on noisy data generated by a program which simulates the hardware system, in order to find the effects of noise on the measurement accuracies.
Backof, C. A., Jr.↗
Thermospheric composition
The global view of the atmosphere provided by satellite observations and radar backscatter measurements has shown a pattern of composition variability resulting largely from dynamic processes. Important progress has been made in defining composition variability at 120 km, which has greatly improved models which previously had fixed boundary conditions at that altitude. The discovery of the early morning maximum in helium abundance and the better definition of diurnal variation in relative composition have provided a basis for more sophisticated dynamical models. Similarly, models of meridional wind systems have been developed which can account for the better-defined winter enhancements in helium and atomic oxygen. Finally, composition variability has indicated the presence of a high-latitude heat source which during periods of magnetic activity profoundly modifies the state of the atmosphere.
Carignan, G. R.↗
Mars surface properties observed by earth-based radar at 70-, 12.5-, and 3.8-cm wavelengths
In the present paper, the results are summarized of a study aimed at determining the small-scale surface properties of Mars (for the Viking project) from a thorough review of all available Martian radar data for the 1973 opposition. Analysis of the quasi-specular echo component showed changes in apparent reflectivity of at least 5 to 1. If attributed entirely to variations in surface material, these correspond to dielectric constants between 1.6 and 4.0. Values of rms surface slope on 1- to 100-m scales range from as low as 0.5 degrees in tablelands near Valles Marineris to more than 3.0 degrees in certain other areas. There is a weak correlation between the small-scale surface characteristics inferred from radar and those inferred from Mariner 9 images and other remote-sensing data sets.
Simpson, R. A.↗
Modelling of equatorial phase and amplitude scintillations from OGO-6 and AE irregularity data
The technique of modelling equatorial phase and amplitude scintillations from in-situ measurements of irregularity amplitude, ambient ionization density and irregularity power spectrum is outlined. The in-situ measurements do not directly provide information on irregularity layer thickness for which radar backscatter observations are utilized. The equatorial scintillation models developed from OGO-6 and AE-C in-situ measurements during the two solstices are presented. Considerable differences in the longitude variation of scintillations are predicted during the two solstices. The model estimates are in good agreement with the available ground based phase and amplitude measurements. Problems associated with the use of bottomside spread-F data for transionospheric propagation modelling at VHF/UHF are also discussed.
Basu, S.↗
Magnetospheric and interplanetary physics 1979-1982
Major trends in the study of magnetospheric and interplanetary physics during the 1979-1982 period are surveyed. Topics discussed include the exploration of the Saturnian and Jovian magnetospheres by Voyagers 1 and 2, the behavior of different ions in the earth magnetosphere, auroral kilometric radiation, computer modeling of global magnetospheric MHD flow, the magnetic substorm, the quiet state, the earth's bow shock, the heliospheric current sheet, and new techniques such as electron beam experiments, 'active' injection experiments, auroral radars, and observations of the earth's distant magnetic tail. The future of this area of research is seen in the combination of data from different spacecraft and ground observations in a single correlated data set, and in the consolidation of past gains by analysis of the large data backlog, while a small number of new missions goes forward.
Stern, D. P.↗
On the detection of underwater bottom topography by imaging radars
A theoretical model which explains basic properties of radar imaging of underwater bottom topography in tidal channels is presented. The surface roughness modulation is described by weak hydrodynamic interaction theory in the relaxation time approximation. In contrast to previous theories on short wave modulation by long ocean waves, a different approximation is used to describe short wave modulation by tidal flow over underwater bottom topography. The modulation depth is proportional to the relaxation time of the Bragg waves. The large modulation of radar reflectivity observed in SEASAT-SAR imagery of sand banks in the Southern Bight of the North Sea are explained by assuming that the relaxation time of 34 cm Bragg waves is of the order of 30-40 seconds.
Alpers, W.↗
Outlook for research on subtropical marine stratiform clouds
A detailed description of the goals and methodology of the First International Satellite Cloud Cover Project Regional Experiment (FIRE) is presented. The purpose of the experiment is to develop physical models and parameterizations of fractional cloud cover over the Pacific Basin. In order to determine fractional cloud cover parameters, satellite observations by radar and lidar instruments will be combined with in situ measurements of the cloud-capped marine boundary layer. A description of a candidate experiment for the program is presented, and some general problems connected with the statistical characterization of satellite imagery are discussed.
Randall, D. A.↗