中低緯度電離層中性風效應(2/2)

The Earth’s upper atmosphere, comprised of the thermosphere and ionosphere, is where neutral and charged particles interact causing complicated physical processes. The ionospheric electron density is highly variable with the latitude, longitude, altitude, local time, season, solar cycle. This research is to construct three-dimensional electron density structures from the coupling between the ionosphere and thermospheric neutral wind. Six microsatellites of the joint Taiwan-US satellite constellation mission, termed FORMOSAT-7/COSMIC-2 (F7), were successfully launched in to a circle low Earth orbit on 25 June 2019. Tri-GNSS Radio occultation System (TGRS) onboard each satellite receiving GPS and GLONASS signals from the United States and Russia, which can dailyprovide more than 4000 vertical electron density profiles. With daily soundings, the vertical electron density profiles derived from the occultation offer a unique advantage of densely sampling the mid- and low-latitude ionosphere, owing to the low-inclination orbits. Dense global electron density probing brings a new era of studying the three-dimensional electron density structures in the mid- and lowlatitude ionosphere. To further understand the dynamic interactions, field-aligned winds computed by the thermospheric eastward/meridional neutral wind fromHorizontal Wind Model (HWM) and magnetic declination/inclination angle from the International Geomagnetic Reference Field (IGRF) are applied to interpret the plasma motions along the magnetic field lines. Moreover, the ion velocity meter (IVM) onboard F7 is an in situ measurement of ion density, temperature, and velocity at the topside ionosphere. A cross-comparison between the field-aligned wind and the F7 measurement is an opportunity to understand the dynamic mechanism of thermosphere-ionosphere coupling. The theory about thermospheric neutral wind effects on the ionosphere can be confirmed by comparing the analysis results of F7 soundings and in situ measurements.