Calculated and observed climate change in the thermosphere, and a prediction for solar cycle 24

The magnitude of the change has been quantified in both approaches, and the source of the secular change attributed to the concentration changes of greenhouse gases. In this study, we use CO2 concentration measured at Mauna Loa Observatory and solar variation based on a proxy model to calculate the secular change of thermosphere neutral density for the last three decades, using a global mean upper atmosphere model.

Our results show that the average density decrease at 400 km from 1970 to 2000 is 1.7% per decade. To quantify the impact of solar activity on the secular change of neutral density, we also calculated the long-term density change under solar minimum and solar maximum conditions for the same time period. The average trends at 350 km and 450 km are 2.2% per decade and 2.9% per decade for solar minimum conditions, while at solar maximum, they are 0.7% per decade and 0.8% per decade, respectively.