Ratio Between Over‐Satellite Electron Content and Plasma Density Measured by Swarm: A Proxy for Topside Scale Height

In-situ plasma density (Ne) and Over-Satellite Electron Content (OSEC) measured at Low-Earth-Orbit (LEO) are basic parameters for analyzing ionospheric plasma. In this study, we calculate the ratio of OSEC to Ne (OSEC-to-Ne ratio; α) by Swarm in daytime topside, which is analogous traditional slab thickness ionosphere. Dependence α on latitude, local time, season, solar activity generally agrees with known climatology vertical scale height (VSH) topside Hence, can be deemed a proxy VSH. Calibrated Swarm-A Swarm-B data two different altitudes further demonstrate that lower-altitude reasonably estimate higher-altitude Ne. addition, new method proposed effective ion mass from electron/ion temperature Swarm. The estimates broadly consistent recent reports composition. All these results usefulness constraining profiles composition Caveats using given, possible directions future improvement discussed.