UARS PARTICLE ENVIRONMENT MONITOR OBSERVATIONS DURING THE NOVEMBER 1993 STORM - AURORAL MORPHOLOGY, SPECTRAL CHARACTERIZATION, AND ENERGY DEPOSITION

During the major storm of November 3-11, 1993, the UARS particle envir onment monitor (PEM), in a 57 degrees inclination, 585-km circular orb it, made measurements of energetic particles, X rays, and magnetic fie ld perturbations in the midnight-dawn magnetic local time sector of th e northern hemisphere and in the noon-evening sector of the southern h emisphere. X-ray images provide a global picture (similar to 20min res olution) of the electron precipitation regions twice per 90-min orbit, which were used to study morphology during the main and recovery phas es of the storm. Detailed examination of the precipitating electrons m easured between 5 eV and 5 MeV show that in the several hundred eV to several hleV energy range the spectra may often be represented by the kappa distribution, which has a thermal character in the keV range and a power law distribution at higher energies. Selected spectral measur ements were used to calculate ionization production rates as functions of altitude. The profiles peak between 95 and 120 km, each having a s econdary ledge at lower altitudes produced by the bremsstrahlung X ray s. We show that the ionization thus produced can be significant at alt itudes as low as the upper stratosphere. Because of the length of time over which this ionization is produced globally, it is expected to ha ve a substantial impact on atmospheric chemistry. Global power inputs to the auroral regions due to precipitating particles have been comput ed for each day of the storm using PEM X-ray and particle observations . On November 4, 1993, the day that includes the main and early recove ry phases of the storm, the northern hemispheric power calculated by i n situ measurement of the electron fluxes was 56.8 GW; that determined by using the X-ray images was 47.4 GW. These values may be compared w ith the northern hemisphere Joule heating rate of 290 GW on the same d ay computed using the PEM magnetometer and electron flux measurements.