Japan Geoscience Union Meeting 2015

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International Session (Oral)

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM06] Mesosphere-Thermosphere-Ionosphere Coupling in the Earth's Atmosphere

Wed. May 27, 2015 11:00 AM - 12:45 PM A01 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Huixin Liu(Earth and Planetary Science Division, Kyushu University SERC, Kyushu University), Yuichi Otsuka(Solar-Terrestrial Environment Laboratory, Nagoya University), Libo Liu(Institute of Geology and Geophysics, Chinese Academy of Sciences), Atsuki Shinbori(Research Institute for Sustainable Humanosphere (RISH), Kyoto University), Chair:Atsuki Shinbori(Research Institute for Sustainable Humanosphere (RISH), Kyoto University)

11:30 AM - 11:45 AM

[PEM06-13] Spatial and temporal extent of ionospheric anomalies during sudden stratospheric warmings in the daytime ionosphere

*Larisa GONCHARENKO1, Anthea COSTER1, Shunrong ZHANG1, Leonid BENKEVITCH1, Ivan GALKIN2 (1.Massachusetts Institute of Technology, Haystack Observatory, 2.University of Massachusetts, Lowell)

Keywords:sudden stratospheric warming, atmospheric coupling, ionosphere

Recent studies have demonstrated large variations in the daytime ionosphere during sudden stratospheric warmings (SSW) and a debate has started about the relative importance of solar and lunar tides in these ionospheric variations. In this study we use GPS TEC data from the MIT Haystack Observatory Madrigal database along 75oW collected in 2000-2014 as well as several digisondes to examine the magnitude and spatio-temporal extent of ionospheric anomalies related to SSW. To separate ionospheric anomalies during SSW from regular ionospheric behavior, we develop empirical models of ionospheric parameters (TEC, NmF2) using available long-term records. The models describe variations in parameters for each lon/lat bin (or digisonde location) as a function of solar activity, geomagnetic activity, day of year, and local time. Ionospheric anomalies are obtained as difference between observations and empirical model. Analysis of anomalies shows that they are observed for both major and minor SSW events, reaching 50-100% variation from expected seasonal behavior for major SSW events and 30-60% variation for minor SSW events. SSW-associated variations are pronounced more strongly in NmF2 than in TEC. The largest variations in TEC in the daytime are observed both in the crests of equatorial ionization anomaly and at 40-60oS (geodetic). Variations in TEC and NmF2 are even discernable up to high latitudes (70oS) in the Southern Hemisphere and mid-latitudes (42oN) in the Northern Hemisphere. We discuss several possible mechanisms contributing to these anomalies, focusing on solar and lunar semidiurnal tides and interhemispheric coupling.