JpGU-AGU Joint Meeting 2017

講演情報

[EE] ポスター発表

セッション記号 A (大気水圏科学) » A-AS 大気科学・気象学・大気環境

[A-AS10] [EE] Interhemispheric and intrahemispheric coupling of the atmosphere

2017年5月23日(火) 15:30 〜 17:00 ポスター会場 (国際展示場 7ホール)

コンビーナ:佐藤 薫(東京大学 大学院理学系研究科 地球惑星科学専攻)、堤 雅基(国立極地研究所)、冨川 喜弘(国立極地研究所)、Xinzhao Chu(University of Colorado Boulder)

[AAS10-P12] Solar wind influence on tropospheric weather through atmospheric vertical coupling

*Paul Prikryl1,2Takumi Tsukijihara3Koki Iwao4Donald B Muldrew5Robert Bruntz6Vojto Rušin7Milan Rybanský8Maroš Turna9Pavel Štastný9Vladimír Pastircák9 (1.Physics Department, University of New Brunswick, Fredericton, NB, Canada、2.Geomagnetic Laboratory, Natural Resources Canada, Ottawa, ON, Canada、3.Department of Earth and Planetary Sciences, Kyushu University, Fukuoka, Japan、4.National College of Technology, Kumamoto College, Yatsushiro, Japan、5.Emeritus, Communications Research Centre, Ottawa, ON, Canada、6.Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA、7.Astronomical Institute, Slovak Academy of Sciences, Tatranská Lomnica, Slovakia、8.Slovak Central Observatory, Hurbanovo, Slovakia、9.Slovak Hydrometeorological Institute, Bratislava, Slovak Republic)

キーワード:Atmospheric gravity wave, Severe weather, Extratropical cyclone, High-speed solar wind, Co-rotating interaction region, Solar wind coupling to the magnetosphere-ionosphere-atmosphere

A link between solar wind magnetic sector boundary structure and mid-latitude upper tropospheric vorticity discovered in the 1970s (Wilcox et al., Science, 180, 185-186, 1973) was later confirmed and physical mechanisms proposed (Tinsley et al., J. Geophys. Res., 106(D23), 1994; Prikryl et al., Ann. Geophys., 27, 1-57, 2009). To further emphasize their importance we investigate the occurrence of mid-latitude severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. It is observed that significant snowstorms, windstorms and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., J. Atmos. Sol.-Terr. Phys., 149, 219–231, 2016) is corroborated for the southern hemisphere. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., Space Sci. Rev., 54, 297–375, 1990) show that propagating waves originating in the thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere thus initiating convection to form cloud/precipitation bands. It is primarily the energy provided by release of latent heat that leads to intensification of storms. These results indicate that vertical coupling in the atmosphere exerts downward control from solar wind to the lower atmospheric levels influencing tropospheric weather development.