Seasonal features of topside scale height based on COSMIC measurements

Plasma scale height is an important parameter of topside ionosphere and contains information about ionospheric physics and dynamic. We investigated the seasonal features of vertical scale height with the electron density profiles from COSMIC. We found that vertical scale height around 660 km at middle latitudes generally has larger values in winter than in summer and had similar structures at March Equinox and September Equinox no matter daytime or nighttime. Bands of large vertical scale height appear at night around ±36° magnetic latitude in all seasons except summer for low solar activity, and mostly appear in winter for moderate solar activity. Vertical scale height in the middle latitudes generally has smaller values for moderate solar activity than that for low solar activity around 660 km, and has smaller values in the daytime than at night.