Local time, substorm, and seasonal dependence of electron precipitation at Lapprox. =4 inferred from riometer measurements
We have examined the variations of electron precipitation at Lapprox. =4 as inferred from riometer measurements of cosmic radio noise absorption made during 1975 at Siple Station and Halley Bay, Antarctica. The results are presented in the form of annual and seasonal averages of 1/2-hourly values for two geomagnetic activity subsets, AE>140 nT (disturbed) and AEless than or equal to 140 nT (quiet). Monthly quiet day curves were used to remove the diurnal and seasonal variations in the background noise levels. Generally, the local time characteristics of the absorption were the same at both stations; the highest absorption occurred in the 0400--1600 MLT sector during disturbed conditions and in the 1200--2000 MLT sector during quiet conditions. For high AE, the highest correlation was obtained at a lag equal to the magnetic local time difference (1.5 hours) between the two stations. On the other hand, for low AE, the highest correlation occurred for a lag of 3.0 hours, nearer the local solar time difference (3.8 hours). Consistently higher absorption was measured at Halley on the average during both levels of magnetic disturbance and in all seasons. At both locations, and for both geomagnetic activity subsets, more absorption was observed in summer and equinox than in winter. This is in contrast to earlier studies for Lgreater than or equal to6, and suggests that a meridional reversal of seasonal behavior occurs between L = 4 and L = 6.
- Research Organization:
- Institute for Physical Science and Technology, University of Maryland, College Park
- OSTI ID:
- 7244767
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 91:A11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
IONOSPHERE
ELECTRON PRECIPITATION
MAGNETIC STORMS
ABSORPTION
CYCLOTRON RESONANCE
DAILY VARIATIONS
DATA ANALYSIS
ELECTRON DRIFT
GEOMAGNETIC FIELD
IONOSPHERIC STORMS
PLASMASPHERE
RADIO NOISE
RIOMETERS
SEASONAL VARIATIONS
TIME DEPENDENCE
CHARGED-PARTICLE PRECIPITATION
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTROMAGNETIC RADIATION
MAGNETIC FIELDS
MEASURING INSTRUMENTS
NOISE
PLANETARY IONOSPHERES
RADIATIONS
RADIOWAVE RADIATION
RESONANCE
VARIATIONS
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena