New 3-D simulations of climate change in the thermosphere

Both of these approaches have shortcomings. Therefore, we have performed new, fully 3-D simulations, using the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere electrodynamics general circulation model, to better quantify secular change rates at various levels of solar activity. These simulations use a 12 year baseline (approximately one solar cycle) in order to more directly compare with measured rates.

Our new findings are in better agreement with observations for solar minimum conditions, approximately -5% per decade at 400 km, and are also still in reasonable agreement at solar maximum, approximately -2% per decade. This confluence of observation and simulation strengthens the case that some of the best evidence of the impact of anthropogenic global change on the upper atmosphere is the continued systematic decrease of thermospheric density.