RELATIVISTIC ELECTRON-FLUXES IN MAY-1992 AND THEIR EFFECT ON THE MIDDLE ATMOSPHERE

Enhancements in the fluxes of relativistic electrons trapped within th e Earth's magnetosphere have been measured by the high-energy particle spectrometer, part of the particle environment monitor on the upper a tmosphere research satellite (UARS). The largest increase in the elect ron fluxes with energies greater than 1 MeV observed on UARS from Octo ber 1991 through July 1994 was in early May 1992. The fluxes of trappe d electrons in the drift loss cone and locally precipitating electrons showed differing buildup and decay rates as a function of invariant l atitude. Increases of more than 2 orders of magnitude were observed in drift loss cone fluxes at magnetic latitudes of 40 degrees-66 degrees and in precipitating fluxes from 48 degrees to 66 degrees. The energy flux contained in the most intense local precipitation observed was s imilar to 0.1 erg cm(-2) s(-1) entering the atmosphere and creating up to 1000 ion pairs cm(-3) s(-1) at 55-km altitude. The daily averaged energy flux from directly precipitating electrons with energies >1 MeV deposited >10(20) erg d(-1) worldwide into the atmosphere for the per iod May 12-21, 1992, producing >10(31) odd nitrogen molecules below 60 -km altitude.