Effect of diffusion-thermal processes on the high-latitude topside ionosphere

We have studied the extent to which diffusion-thermal heat flow affects H ⁺ temperatures in the high-latitude topside ionosphere. Such a heat flow occurs whenever there are H ⁺-O ⁺ relative drifts. From our study we have found that at high-latitudes, where H ⁺ flows up and out of the topside ionosphere, diffusion-thermal heat flow acts to reduce H ⁺ temperatures by 500-600 K at altitudes above about 900 km.