Ground Echoes Observed by the Meteor Radar and High‐Speed Auroral Observations in the Substorm Growth Phase

DOI Web Site Web Site Web Site 参考文献11件 オープンアクセス
  • A. Kozlovsky
    Sodankylä Geophysical Observatory University of Oulu Sodankylä Finland
  • S. Shalimov
    Institute of Physics of the Earth Moscow Russia
  • S. Oyama
    Institute for Space‐Earth Environmental Research Nagoya University Nagoya Japan
  • K. Hosokawa
    Ionospheric Physics Unit, University of Oulu Oulu Finland
  • M. Lester
    Department of Physics and Astronomy University of Leicester Leicester UK
  • Y. Ogawa
    National Institute of Polar Research Tokyo Japan
  • C. Hall
    Tromsø Geophysical Observatory The Arctic University of Norway Tromsø Norway

書誌事項

公開日
2019-11
資源種別
journal article
権利情報
  • http://onlinelibrary.wiley.com/termsAndConditions#vor
DOI
  • 10.1029/2019ja026829
公開者
American Geophysical Union (AGU)

この論文をさがす

説明

<jats:title>Abstract</jats:title><jats:p>Multi‐instrument observations by a meteor radar (MR), auroral cameras, ionosondes, and ground magnetometers were made in Northern Europe at auroral latitudes (between 64° and 72° corrected geomagnetic latitude) at 22–24 magnetic local time in the substorm growth phase. The southward drifting growth phase auroral arc was associated with enhanced electron density up to 2⋅10<jats:sup>12</jats:sup> m<jats:sup>‐3</jats:sup> (corresponding to a plasma frequency, <jats:italic>foEs</jats:italic> of about 13 MHz) at about 110‐km altitude. Such an enhanced <jats:italic>E</jats:italic> layer electron density caused bending toward the ground of the MR radio waves transmitted at a frequency, <jats:italic>f</jats:italic><jats:sub><jats:italic>r</jats:italic></jats:sub>, of 36.9 MHz and at low elevation (<jats:italic>el</jats:italic>. < 25°), such that the radar received ground echoes characterized by a near‐zero Doppler shift. The amplitude of the echoes was modulated at a frequency of a few hertz, and a similar modulation was found in the auroral luminosity at 427.8 nm near the location of the bending of MR radio waves. The modulation was due to irregular (random) fluctuations of auroral precipitation. Although such a few‐hertz variation of the auroral precipitation cannot produce more than 1% modulation of the ionospheric electron density, even such a small modulation can lead to 50% modulation of the MR ground scatter provided <jats:italic>foEs</jats:italic> ≈ <jats:italic>f</jats:italic><jats:sub><jats:italic>r</jats:italic></jats:sub> sin (<jats:italic>el</jats:italic>.). The ionosonde and MR data provide evidence that this condition was satisfied in the present case. Due to a high‐frequency (>2 Hz) amplitude modulation of the ground scatter, the MR erroneously accepts such signals as echoes from meteor trails.</jats:p>

収録刊行物

参考文献 (11)*注記

もっと見る

関連プロジェクト

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ