Measurements of inner zone electron precipitation

Journal Article · Tue Jan 01 00:00:00 EST 1980 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA085iA01p00009· OSTI ID:5460675

Imhof, W L; Reagan, J B; Gaines, E E

Energetic electron (> or approx. =0.16 MeV) data taken from November 1972 to April 1973 from over 1000 passes of a low-altitude (approx.750 km) noon-midnight polar-orbiting satellite across the L=1.75 field line in both the northern and southern hemispheres have been analyzed for evidence of the longitude and local time distributions in electron precipitation on that field line. The precipitation processes were observed to be weak, at least near local noon and midnight, as evidenced from the negligible fluxes observed at all pitch angles when the conjugate point is below sea level and from the absence of any direct observation of electrons at L=1.75 in the bounce loss cone at all longitudes. By observing quasi-trapped fluxes with a spectrometer having a large geometric factor, a high sensitivity was achieved for detecting electron precipitation and measuring the energy spectra with fine resolution. The data have been analyzed and found to show that prounounced precipitation events near local noon and midnight were a rare occurrence between approx.60 /sup 0/E and approx.100 /sup 0/E. In the approx.100 /sup 0/E to approx.180 /sup 0/E longitude region, significant fluxes of quasi-trapped electrons were often observed with a very pronounced noon-midnight asymmetry. The quasi-trapped fluxes observed locally in the region were often large near midnight but seldom significant near noontime. From the electron data it was found that within a given local time and longitude interval the fluxes were widely variable, indicating that the precipitation mechanism(s) were not steady in time. Also, during the time period of observation, the average intensities of the quasi-trapped electrons were higher at times of high negative Dst.

• Research Organization: Space Sciences Laboratory, Lockheed Palo Alto Research Laboratory, Palo Alto, California 94304
• OSTI ID: 5460675
• Journal Information: J. Geophys. Res.; (United States), Vol. 85:A1
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
RADIATION BELTS
ELECTRON PRECIPITATION
DAILY VARIATIONS
ENERGY SPECTRA
INCLINATION
KEV RANGE 100-1000
MAGNETOSPHERE
TRAPPED ELECTRONS
CHARGED-PARTICLE PRECIPITATION
EARTH ATMOSPHERE
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
KEV RANGE
LEPTONS
SPECTRA
VARIATIONS
640203* - Atmospheric Physics- Magnetospheric Phenomena- (-1987)