Equatorial electrodynamics and neutral background in the Asian sector during the 2009 stratospheric sudden warming

Publication: Research - peer-reviewJournal article – Annual report year: 2011

  • Author: Liu, Huixin

    Kyushu University, Japan

  • Author: Yamamoto, Mamoru

    Kyoto University

  • Author: Ram, S. Tulasi

    Kyoto University

  • Author: Tsugawa, Takuya

    Japan National Institute of Information and Communications Technology

  • Author: Otsuka, Yuichi

    Nagoya University

  • Author: Stolle, Claudia

    Solar System Physics, National Space Institute, Technical University of Denmark

  • Author: Doornbos, Eelco

    Delft University of Technology

  • Author: Yumoto, Kiyohumi

    Kyushu University, Japan

  • Author: Nagatsuma, Tsutomu

    Japan National Institute of Information and Communications Technology

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Using ground observations of total electron content (TEC) and equatorial electrojet (EEJ) in the Asian sector, along with plasma and neutral densities obtained from the CHAMP satellite, we investigate the ionospheric electrodynamics and neutral background in this longitude sector during the major stratospheric sudden warming (SSW) in January 2009. Our analysis reveals the following prominent features. First, the TEC response in tropical regions is strongly latitude dependent, with monotonic depletion at the dip equator but a semidiurnal perturbation at low latitudes. Second, the TEC semidiurnal perturbation possesses a significant hemispheric asymmetry in terms of onset date and magnitude. It starts on the same day as the SSW peak in the Northern Hemisphere but 2 days later in the Southern Hemisphere. Its magnitude is twice as strong in the north than in the south. Third, strong counter electrojet occurs in the afternoon, following the strengthening of the eastward EEJ in the morning. Fourth, semidiurnal perturbation in both TEC and EEJ possesses a phase shift, at a rate of about 0.7 h/day. Comparisons with results reported in the Peruvian sector reveal clear longitude dependence in the amplitude and hemispheric asymmetry of the semidiurnal perturbation. Finally, thermospheric density undergoes similar to 25% decrease at low latitudes in the afternoon local time sector during the SSW, indicating significant cooling effects in the tropical upper thermosphere.
Original languageEnglish
JournalJournal of Geophysical Research
Pages (from-to)A08308
StatePublished - 2011
CitationsWeb of Science® Times Cited: 32
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