Hsu, Chih-TeHeelis, Roderick A.2018-08-202018-08-202017-05-102018-08-202169-9380http://hdl.handle.net/10735.1/5974Recently reported measurements from the Defense Meteorological Satellite Program (DMSP) indicate that the O⁺ temperature in the topside ionosphere is dependent on the fractional H⁺ density. This finding indicates that the mass-dependent energy exchange rate between O⁺ and H⁺ plays an important role in the thermal balance of the topside ionosphere. In this study we utilize the SAMI2 model to retrieve both T_{H⁺} and T_{O⁺} and verify the previously observed dependence of ion temperature on ion composition. The model shows that in the topside at middle latitudes when a single ion is dominant, O⁺ or H⁺ is heated by electron collisions and cooled by conduction as expected. However, in the intervening altitude region where both O⁺ and H⁺ are present, O⁺ is heated by collisions with H⁺ and cooled by conduction, while H⁺ is heated by collisions with electrons and cooled by collisions with O⁺.en©2017 American Geophysical Union. All Rights Reserved.IonosphereIncoherent scatter radarElectronsIonsAtmospherearticleHsu, Chih-Te, and Roderick A. Heelis. 2017. "Modeling the daytime energy balance of the topside ionosphere at middle latitudes." Journal of Geophysical Research-Space Physics 122(5): 5733-5742.1225