Intensity distribution of dayside polar soft electron precipitation and the IMF

The influence of the Bz and By polarity of the IMF on the location of the dayside regions of precipitating, low energy electrons recorded by the DMSP F-2 satellite, is investigated. The average differential electron flux was determined for 2 months during local summer. It is found that the spatial distributions are similar for electrons in the range from 50 to 183 eV. The region of maximum intensity for Kp⩽ 2+ over the Southern Hemisphere is located on the opposite side of noon from the Northern Hemisphere. The current intensity carried by precipitating electrons in the cusp region agrees with that measured by the TRIAD magnetometer. When the IMF is northward a marked asymmetry of the low energy electron precipitation between positive and negative By cases is observed. For positive By the maximum electron flux occurs between 0800 and 1200 M.L.T.and −76 and −83° M.L.A.T.and for negativeBythe region occurs between 1200 and 1500 M.L.T. and −79 and −82° M.LAT. The dynamical variations associated with substorm activity when the IMF is southward obscure the expected By effect.