Rate of erosion of dayside magnetic flux based on a quantitative study of the dependence of polar cusp latitude on the interplanetary magnetic field

Journal Article · Thu Nov 01 04:00:00 EST 1973 · Radio Science

DOI:https://doi.org/10.1029/RS008i011p00955· OSTI ID:4420098

Burch, J. L.

>By considering only those periods when the delay time from the interplanetary observing position to the magnetosphere is less than about 5 min, it is found that irrespective of substorm activity: (a) the 45-min average value of interplanetary B/sub z/ predicts the latitudes of the poleward and equatorward boundaries of polar cusp electron precipitation with rms errors of 1.34 deg and 1.16 deg respectively; (b) both boundaries move equatorward by about 5 deg as B/ sub z/ varies from 0 to --6 gamma , the cusp remaining about 4 deg wide; (c) the amount of flux added to the polar cap is about 9.2% of the total southward flux impingment on the magnetosphere in the previous 45 min; and (d) as B/sub z/ becomes more positive, the equatorward boundary moves only slightly more poleward (1/2 deg between B/sub z/ = 2 gamma and B/sub z/ = 6 gamma ), while the poleward boundary moves significantly toward higher latitudes, resulting in a cusp approximately 7 deg wide for B/sub z/ = 6 gamma . This dependence of the width of the cusp on positive B/sub z/ suggests that reconnection between the IMF (interplanetary magnetic field) and open geomagnetic field lines (which are southward near the dayside magnetopause) is facilitated when the IMF is northward, allowing deeper penetration of magnetosheath plasma into the high latitude magnetosphere. (auth)

• Research Organization: Goddard Space Flight Center, Greenbelt, MD
• Sponsoring Organization: USDOE
• NSA Number: NSA-29-008610
• OSTI ID: 4420098
• Journal Information: Radio Science, Journal Name: Radio Science Journal Issue: 11 Vol. 8; ISSN 0048-6604
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

*INTERPLANETARY SPACE-- MAGNETIC FIELDS
*MAGNETOSHEATH-- MOTION
*MAGNETOSPHERE-- POLAR REGIONS
ELECTRON PRECIPITATION
LATITUDE EFFECT
MAGNETIC BAYS
MAGNETIC FLUX
N58300* --Physics (Atmospheric)--Magnetospheric Phenomena
PLASMA