Observation of thermosphere and ionosphere using the ionosphere PhotoMeter (IPM) on the Chinese meteorological satellite FY-3D

Abstract

The Ionosphere PhotoMeter (IPM) is a far ultraviolet nadir-viewing photometer that flew aboard the second-generation, polar-orbiting Chinese meteorological satellite Feng-Yun 3D (FY-3D), which was launched on November 25th, 2017. By observing far ultraviolet night-time OI 135.6 nm emissions, which are produced by the recombination of O+ ions and electrons, the F2 layer peak electron density (NmF2) can be deduced. During daytime IPM was designed to measure the OI 135.6 nm and N2 Lyman-Birge-Hopfield (LBH) band emissions, which would be used to infer the O/N2 ratio, a key diagnostic of neutral dynamics in the daytime. The paper shows the measurement results from IPM taken during its initial months of Operation. A quantitative comparison showing NmF2 from IPM and ground-based ionosondes is presented, and the correlation value R between the ground-based ionosondes and the satellite NmF2 is 0.91. The global O/N2 ratio distribution during geomagnetic storm on 25 through 30 August is presented and illustrated, which could show the latitudes of the ionospheric positive/negative storm in different longitude ranges. The O/N2 ratio significantly decreases during the main and recovery phase of the storm as expected. The correlation value R between the O/N2 ratio retrieved from IPM data and the ionospheric electron density provided by ground-based ionosondes during storms in August 2018 is about 0.78.