9320426 Sivjee This award is for joint radar and optical investigations of the interactions between the atmospheric constituents in the polar thermosphere and precipitating auroral electrons. The latter dissipate most of their energy through a combination of processes involving dissociation, excitation and ionization of some of the upper atmospheric constituents. In turn, the byproducts of these processes interact with ambient air particles to modify polar thermospheric composition and thermodynamics. All these upper atmospheric auroral processes can be investigated by combining ground-based remote sensing measurements of auroral ionization profiles using incoherent scatter radar (ISR) sounding of the auroral region, and concurrent bore-sighted spectroscopic and interferometric observations of the optical signatures of the auroral electron excitation of N2, O2, O and N. The data base for these studies will be constructed from the ISR and Spectro- interferometric observations of auroral displays occurring over Sondrestromfjord in Greenland. ***
