题目：Observations and Simulations of Ionospheric Storm-enhanced Density and Tongue of Ionization

报告人：刘晶 美国大气研究中心，高山天文台

时间：2016年7月21日下午3:00

地点：南楼208.

Observations and Simulations of Ionospheric Storm-enhanced Density and Tongue of Ionization

Abstract：There are still uncertainties regarding the formation mechanisms for storm-enhanced density (SED) in the high and subauroral latitude ionosphere. We deploy the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM) and GPS total electron content (TEC) observations to identify the principle mechanisms for SED and the tongue of ionization (TOI) through term-by-term analysis of the ion continuity equation, and also find the advantages and deficiencies of the TIEGCM in capturing high- and subauroral latitude ionospheric fine structures for the two geomagnetic storm events occurring on 17 March 2013 and 2015.

The model is also run for different Universal Times (UT) and Interplanetary Magnetic Field (IMF) conditions. It is found that: (1) The TOI formation is critically dependent on UT, preferentially near 2000 UT in the Northern Hemisphere (NH) and near 1600 UT in the Southern Hemisphere (SH). These are the intervals when the high-latitude ion convection throat is closer to the middle-latitude high plasma density source region, so that more plasma can be directly transported into the polar cap region; (2) this different UT dependence between the two Hemispheres occurs, not only because of the different separation of the magnetic poles from the geographic poles in the two hemispheres, but also because of the UT dependence of the mid-latitude source locations (local time, latitude) and the magnitude of plasma density enhancements.

刘晶：2012年获得中国科学院地质与地球物理研究所博士学位，曾获得过中科院院长奖以及中科院优秀博士论文。先后在日本国立极地研究所和美国大气研究中心高山天文台工作。