The distribution of nitric oxide at 150 km

Abstract

"The objectives of this thesis are to determine the morphology of nitric oxide at the altitude of 150 km and to determine what drives the observed variability. Those objectives are accomplished by characterizing satellite observations of nitric oxide at that altitude and comparing them with those at 106 km, the altitude of peak density. The global distribution of nitric oxide and its response to geomagnetic activity vary between the two altitudes. At 150 km, nitric oxide is most abundant at high latitudes in the sunlit summer hemisphere, in contrast to nitric oxide at 106 km, which is most abundant at high latitudes in the winter hemisphere. The high-latitude component of nitric oxide at both altitudes is associated with geomagnetic activity, although the primary production mechanisms differ between the two altitudes. At 106 km, high-latitude nitric oxide density enhancements are driven by particle precipitation. At 150 km, nitric oxide at high latitudes is enhanced by increased temperatures arising from Joule heating. Enhancements at 150 km occur more rapidly than those at 106 km. At both altitudes, the response of nitric oxide to geomagnetic activity exhibits a seasonal variation that is attributed to seasonal variations in the production mechanisms"--Leaf iii