Přednášky hostů z Taiwanu

Přednášky proběhnou ve čtvrtek 5.9.2019 od 9:30 ve velké zasedačce ÚFA.

Tiger J.Y. Liu, Loren C. Chang, Fu-Yuan Chang, and CAPE Team

Center for Astronautical Physics and Engineering (CAPE); Graduate Institute of Space Science and Engineering; and Center for Space and Remote Sensing Research, National Central University, TAIWAN

Model and Observational Studies of Ionosphere Variability and Coupling at National Central University

This talk will report on research results into vertical coupling effects on plasma bubble variability using COSMIC and numerical simulations, as well as ongoing work at NCU on the development and operation of small spacecraft for in-situ ionospheric studies. COSMIC observations have been used to identify a nighttime wave-2 structure in the equatorial boreal summer ionosphere consistent with preconditioning favorable for plasma bubble formation over the African and Central Pacific sectors. Numerical experiments using TIE-GCM show that this wave-2 feature can be produced via forcing by specific nonmigrating atmospheric tides via the E region dynamo, providing evidence that plasma bubble variability can be linked to vertical coupling effects. 

Small satellites are increasingly becoming a feasible platform for ionospheric studies. NCU is currently involved in the development of four small satellite missions for upper atmospheric research, of which two are as primary developer. These two missions are IDEASSat - a 3U CubeSat carrying the Compact Ionospheric Probe (CIP) in-situ plasma sensor with launch scheduled for 2020, and SCION - a ~12U CubeSat carrying CIP, a GNSS radio occultation payload, and a hyperspectral imager. The operational concepts and lessons learned in the development of these two missions will be presented, as well as the possibility for collaborations in related research and operations.

Ionospheric and Atmospheric GNSS Radio Occultations of FORMOSAT-3/COSMIC and FORMOSAT-7/COSMIC

FORMOSAT-3/COSMIC (F3/C) constellation launched on 15 April 2006, which consists of six micro-satellites in the low-earth orbit at 800 km altitude with 72-deg inclination, is capable of uniformly monitoring the atmosphere (200 meter – 60 km altitude) and ionosphere (90-800 km altitude) by using the powerful radio occultation (RO) technique. More than 2000 GPS RO atmospheric temperature and electron density profiles per day provide excellent opportunities to carry out weather forecast, climate observations, and ionospheric weather monitoring of the globe. This paper reports F3/C applications on typhoon forecast, storm/earthquake/tsunami disturbances, ionospheric weather monitoring/nowcast/forecast, and S4 scintillation. Finally, impacts of impacts and prospects of F3/C follow-on, FORMOSAT-7/COSMIC-2, which consists of six small-satellites onboard GNSS RO receiver, IVM (ion velocity meter), RF beacon, low inclinations of 24-deg at 550 km altitude, launched on 24 June 2019 are briefed.

A Study on Ionospheric Neutral Wind Signatures by Using FORMOSAT-3/COSMIC and FORMOSAT-5/AIP

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 altitude, latitude, longitude, local time, season, solar cycle.  This paper reports the investigation of the nighttime features from the coupling between the ionosphere and thermospheric neutral wind.  Two interesting phenomena associated with the electrodynamic processes are examined, which include (1) The Weddell Sea Anomaly (WSA) in southern mid to high-latitude and Siberia-Yakutsk Anomaly (SYA) in northern mid-latitude. The increasing anomalies of electron density are most prominent over the Weddell Sea region in the southern hemisphere and Siberia and Yakutsk areas in the northern hemisphere during local summer nighttime; and (2) The Plasma Depletion Bays (PDBs) at equatorial/low-latitude.  These features of the electron density are observed at the evening/night hours near magnetic equator in four longitude regions over Southwest America, North Atlantic, India Ocean, and Southeast Asia. The thermospheric meridional and zonal winds simulated by Horizontal Wind Model 1993 (HWM93) is applied to interpret the plasma motions along the magnetic field lines associated with the WSA/SYA and PDB features.  Results indicate that blowing of the thermospheric neutral winds play an important role in the formation of the two anomalies and bay features.