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Anderson, A. D.

Publications and source records attributed to Anderson, A. D..

9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Optical image of a cometary nucleus: 1980 flyby of Comet Encke

The feasibility was investigated of obtaining optical images of a cometary nucleus via a flyby of Comet Encke. A physical model of the dust cloud surrounding the nucleus was developed by using available physical data and theoretical knowledge of cometary physics. Using this model and a Mie scattering code, calculations were made of the absolute surface brightness of the dust in the line of sight of the on-board camera and the relative surface brightness of the dust compared to the nucleus. The brightness was calculated as a function of heliocentric distance and for different phase angles (sun-comet-spacecraft angle).

Wells, W. C.↗
NASA NTRS1974

Analysis of data from spacecraft (stratospheric warmings)

Links between the upper atmosphere and the stratosphere were studied to explain stratospheric warmings, and to correlate the warmings with other terrestrial and solar phenomena. Physical mechanisms for warming, or which may act as a trigger are discussed along with solar and geophysical indices. Two stratospheric warming cases are analyzed.

Anderson, A. D.↗
NASA NTRS1974

Analysis of data from spacecraft relating to stratospheric warmings

A detailed study of six different stratospheric warmings is described which establishes that the magnetic indices AE, Ap, and Dst display a marked increase 1 to 3 days before warming phenomena and a marked decrease at 0 and -4 days. The definite correlation of the warming phenomena with the AE index indicates that the auroral electrojet joule heating near 100 km may be the original source of the heating that influences the atmosphere at 50 km and below. Whether this heating is the primary cause or trigger of stratospheric warmings remains to be determined.

Weiss, R.↗
NASA NTRS1972

Variations of atmospheric density near 400 km with magnetic activity during the storm period of 28 September to 2 October 1969

Neutral density data were obtained near 400 km (1600 LT) from a microphone density gage on OGO-6 from 0 to 40 deg N geomagnetic latitude for 25 September through 3 October 1969. Several geomagnetic storms occurred during this period. Least squares fits were made to data points on density scatter diagrams. An equation representing the least squares fit was computed for each delay time. The equation of best fit (and the corresponding time delay between the density and the magnetic index which resulted in this best fit) was found by choosing the equation that gave the minimum standard error. The implications of the time differences associated with the best fits at various latitudes and longitudes are discussed with regard to the time delays involved in geomagnetic heating of the neutral upper atmosphere.

Anderson, A. D.↗
NASA NTRS1972

Neutral density measurements near 400 kilometers by a microphone density gage on Ogo 6 during July 12-15, 1969.

Analysis of persistent density peaks (maxima) measured near 400 km during daytime (1425 LT) by a microphone density gauge on Ogo 6 during July 12 to 15, 1969. Most of the density peaks occurred between geomagnetic latitudes 50 and 61 N and L values 2.3 and 4.7. The average density change in the peaks was 27%. Most of the peaks appeared in the longitude sector from 150 to 350 E. No density peaks were measured in the 50 to 130 E sector during the 3-1/2 day observation period. A persistent pair of density peaks was present on seven successive orbits during July 13 and July 14 (both geomagnetically disturbed days) near geomagnetic latitudes 53 and 61 N, respectively.

Anderson, A. D.↗
NASA NTRS1969

The upper atmosphere

Upper atmospheric composition, temperature, density, and pressure, and their variations

Anderson, A. D.↗
NASA NTRS1969

Nonpenetrating radiations

Solar radiation, albedo, and thermal radiation environment of earth and moon orbiting satellites

Anderson, A. D.↗