Middle-low latitude neutral composition and temperature responses to the 20 and 21 November 2003 superstorm from GUVI dayside limb measurements

TIMED/Global Ultraviolet Imager (GUVI) limb measurements of far-ultraviolet airglow emission have been used to investigate middle-low latitude thermospheric composition and neutral temperature responses to the 20 and 21 November 2003 (day of year [DOY] 324 and 325) superstorm. Altitude profiles of O, N-2 number densities and temperature, as well as O/N-2 column density ratio ( n-ary sumation O/N-2), on the storm days along the GUVI limb tracks are compared with those on DOY 323 (quiet time). The storm-time composition and temperature responses were global and evolved continuously as the storm progressed. Specially, N-2 and temperature increased almost globally at all altitudes during the storm and their perturbation structures were similar. The magnitudes of their enhancements both increased with altitude and latitude. The storm-induced O perturbations decreased in the lower thermosphere but increased in the upper thermosphere. Transition heights of O perturbations from decrease to increase changed with latitude and time. During the storm main and recovery phases, the storm-induced n-ary sumation O/N-2 decreases were mostly related to the O depletion in the low-middle thermosphere, whereas n-ary sumation O/N-2 increases during the storm were primarily caused by N-2 depletion. There was a remarkable hemispheric asymmetry in composition responses as they have different morphologies and lifetime, especially during the storm recovery phase.