Characteristics of intense electromagnetic energy input to the high-latitude thermosphere [presentation]
Maute, A., & Richmond, A. D. (2008). Characteristics of intense electromagnetic energy input to the high-latitude thermosphere [presentation]. In AGU Joint Assembly 2008. American Geophysical Union: Ft. Lauderdale, FL, US.
Electromagnetic energy transfer from the magnetosphere to the high-latitude thermosphere occurs over a range of spatial scales. Most of this energy is converted into Joule heating in the thermosphere. Some aspects of the thermospheric response to this energy input, especially the composition, dep... Show moreElectromagnetic energy transfer from the magnetosphere to the high-latitude thermosphere occurs over a range of spatial scales. Most of this energy is converted into Joule heating in the thermosphere. Some aspects of the thermospheric response to this energy input, especially the composition, depend nonlinearly on the intensity of the heating, such that intense heating occurring in a small region can produce a greater global-scale thermospheric composition response than the same amount of heat deposited over a broader area, with less peak intensity. In order to simulate the global thermospheric composition response to high-latitude Joule heating, we therefore need information about the spatial scales and intensities of the energy input. Using the downward perturbation Poynting flux derived from electric- and magnetic-field measurements on the Dynamics Explorer-2 spacecraft as a measure of height-integrated Joule heating, we analyze the characteristic spatial scales of this heating. In addition we study the magnitude and probability distribution of heating intensity as a function of magnetic latitude and magnetic local time (MLT). For most MLTs the most intense heating feature has a width on the order of 1 degree (full width at half maximum) in magnetic latitude, and contains roughly half of the total Joule heating integrated across the auroral oval. The results of this study are used to examine the influence of the concentrated Joule heating on the mixing of thermospheric constituents by including it in a numerical model. The effects of the concentrated Joule heating on the mixing of thermospheric constituents is discussed in a companion presentation. Show less