HR: 1330h
AN: SA22A-0104    [PDF]
TI: Simple Diffusion Theory Models for Joule Heating in the Thermosphere
AU: * Tan, A
EM: ata@aamu.edu
AF: Alabama A & M University, Box 447, Normal, AL 35762 United States
AU: Zhang, X
EM: zhangx@cspar.uah.edu
AF: Alabama A & M University, Box 447, Normal, AL 35762 United States
AU: Lyatsky, W
EM: lyatsky@cspar.uah.edu
AF: Alabama A & M University, Box 447, Normal, AL 35762 United States
AU: Germany, G A
EM: germanyg@cspar.uah.edu
AF: Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35899 United States
AU: Wu, S T
EM: wus@cspar.uah.edu
AF: Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35899 United States
AB: The precipitation of accelerated charged particles and strong increases in ionospheric currents during geomagnetic disturbances take place mainly in the auroral oval. This energy is transmitted to the thermosphere, raising exospheric temperatures there. The thermal energy is transmitted equatorward by gravity waves and neutral winds which can be described by a diffusion equation with some suitable diffusion coefficient. The observed dependence of the enhancement of the exospheric temperature on geomagnetic latitude and the Kp index is determined. Simple diffusion theory models for the latitudinal variation of Tinf are obtained by solving the heat equation in a two-dimensional plane and transforming the solution on to the curved spherical surface of the thermosphere. Analytical solutions for three simple models are obtained: (1) An instantaneous line source at the geomagnetic pole; (2) An instantaneous cylindrical source covering the auroral oval and the polar cap; and (3) An instantaneous annular cylindrical source coinciding with the auroral oval. Models 1 and 2 yield good agreements with the observed latitudinal variation of Tinf with suitable choices of the standard deviations. Model 3 gives only fair agreement with observation.
DE: 0358 Thermosphere--energy deposition
DE: 2118 Energetic particles, solar
DE: 2716 Energetic particles, precipitating
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting