Journal Article

Retrospect and prospect of ionospheric weather observed by FORMOSAT-3/COSMIC and FORMOSAT-7/COSMIC-2

Lin, Charles Chien‐Hung, Chang, Fu-Yuan, Lee, I-Te, Chen, Shih-Ping, Rajesh, Panthalingal Krishnanunni, Lin, Chi‐Yen, Matsuo, Tomoko, Liu, Tiger Jann-Yenq, Chen, Chia-Hung, Tsai, Ho‐Fang, Hsu, Chih-Ting, Sun, Yang-Yi

2022

Overview

FORMOSAT-3/COSMIC (F3/C) constellation of six micro-satellites was launched into the circular low-earth orbit at 800 km altitude with a 72-degree inclination angle on 15 April 2006, uniformly monitoring the ionosphere by the GPS (Global Positioning System) Radio Occultation (RO). Each F3/C satellite is equipped with a TIP (Tiny Ionospheric Photometer) observing 135.6 nm emissions and a TBB (Tri-Band Beacon) for conducting ionospheric tomography. More than 2000 RO profiles per day for the first time allows us globally studying three-dimensional ionospheric electron density structures and formation mechanisms of the equatorial ionization anomaly, middle-latitude trough, Weddell/Okhotsk Sea anomaly, etc. In addition, several new findings, such as plasma caves, plasma depletion bays, etc., have been reported. F3/C electron density profiles together with ground-based GPS total electron contents can be used to monitor, nowcast, and forecast ionospheric space weather. The S4 index of GPS signal scintillations recorded by F3/C is useful for ionospheric irregularities monitoring as well as for positioning, navigation, and communication applications. F3/C was officially decommissioned on 1 May 2020 and replaced by FORMOSAT-7/COSMIC-2 (F7/C2). F7/C2 constellation of six small satellites was launched into the circular low-Earth orbit at 550 km altitude with a 24-degree inclination angle on 25 June 2019. F7/C2 carries an advanced TGRS (Tri Gnss (global navigation satellite system) Radio occultation System) instrument, which tracks more than 4000 RO profiles per day. Each F7/C2 satellite also has a RFB (Radio Reference Beacon) on board for ionospheric tomography and an IVM (Ion Velocity Meter) for measuring ion temperature, velocity, and density. F7/C2 TGRS, IVM, and RFB shall continue to expand the F3/C success in the ionospheric space weather forecasting. Key Points FORMOSAT-3/COSMIC and FORMOSAT-7/COSMIC-2 uniformly observe 3D electron density. FORMOSAT-3 and FORMOSAT-7 enable ionospheric weather forecasting. FORMOSAT-7/COSMIC-2 TGRS and IVM have a better understanding of the electrodynamics of ionospheric plasma.

• Publisher: Springer Nature Singapore,Springer
• Subject: Atmospheric Sciences / Earth and Environmental Science / Earth Sciences / FORMOSAT-3/COSMIC / FORMOSAT-7/COSMIC-2 / GNSS / Ionospheric weather / Oceanography / Original Article / Radio occultation