Hemispherical asymmetry in cusp precipitation near solstices

Journal Article · Fri Apr 01 00:00:00 EST 1988 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA093iA04p02643· OSTI ID:5265674

Newell, P T; Meng, C

A statistical comparison of the peak flux in electron and ion polar cusp precipitation in the summer and winter hemispheres as observed by the low-altitude DMSP F7 satellite is performed. Data studied encompass four consecutive solstices from December 1983 to June 1985, comprising 77 days of data with a total of 292 individual cusp passes. On each day, observations were restricted to those few hours UT in which the interhemispherical MLT variation of DMSP F7 was smallest. After the remaining local time effect was averaged out, the summer hemisphere ion (electron) precipitating energy flux was larger, on the average, by 61 +- 11% (51 +- 5%) than that in the winter hemisphere. However, the average particle energy was always lower for both species in the summer hemisphere. These effects generally hold true for northward as well as southward interplanetary magnetic fields (IMF). It is argued that the observed asymmetry is very hard to explain if the most intense part of the cusp lies on closed field lines, but it is shown that the standard open field line model of the cusp virtually requires the observed differences to occur. The present results thus suggest that the most intense portion of the cusp lies on open field lines even for northward IMF. copyright American Geophysical Union 1988

• Research Organization: The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland
• OSTI ID: 5265674
• Journal Information: J. Geophys. Res.; (United States), Vol. 93:A4
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
POLAR CUSP
CHARGED-PARTICLE PRECIPITATION
ASYMMETRY
FLUX DENSITY
INTERPLANETARY MAGNETIC FIELDS
MATHEMATICAL MODELS
SEASONAL VARIATIONS
SOLAR WIND
MAGNETIC FIELDS
SOLAR ACTIVITY
VARIATIONS
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena