Long-term trend of topside ionospheric electron density derived from DMSP data during 1995-2017

However, little attention has been paid to the topside ionosphere trend. In this study, the unique in situ data measured by series Defense Meteorological Satellite Program (DMSP) satellites were utilized to derive the long-term trend of the topside ionosphere for the first time.

We checked carefully data quality, gap, and consistency between different satellites for both electron density and ion temperature, and compared the techniques of artificial neuron network (ANN) and multiple linear regression methods for deriving the trend. The electron density (N-e) trend in the middle and low latitudes at similar to 860 km around 18 MLT was derived using the ANN method from 1995-2017. The trend from DMSP observations has a mean magnitude ranging from similar to- 2% to similar to 2% per decade, with clear seasonal, latitude and longitude variations.