Examing the effects of periodic high latitude forcing on the Joule heating and thermospheric temperature structure

High latitude Joule heating is one of the main causes for the rapid increase of temperature in the thermosphere. This increase in temperature is advected to lower latitudes, and can therefore raise the global mean thermospheric temperature. This rise in temperature can lift the atmosphere, increasing drag on satellites. Many global models have had a difficult time modeling this energy input accuurately. Codrescu[1995] showed that the variability in the high latitude E-field can significantly increase the amount of Joule heating, which has been consistenly underestimated in global models. Using the AMIE procedure, Crowley and Hackert[2001] argued that a significant fraction of this variability arises from oscillations with period less than one hour. While it is understood that the thermosphere responds differently at different frequencies, this effect has not been thoroughly quantified. We use the Global Ionosphere-Thermosphere Model(GITM) to simulate the thermospheric reaction to some simple sin-waves in the highlatitude forcing terms to determine the different frequencies which will optimize the Joule heating in the thermosphere at different altitudes. We then test the idea of variability by adding different levels of random noise to the E-field to check the changes of the Joule heating. So we are able to examine the effects of driving to the thermosphere-ionosphere at different frequencies and quantify the effect of the E-field variability on the Joule heating and the thermospheric temperature structure.