Spatial variability of solar quiet fields along 96° magnetic meridian in Africa: Results from MAGDAS

O. S. Bolaji, A. B. Rabiu, O. R. Bello, A. Yoshikawa, K. Yumoto, O. O. Odeyemi, O. Ogunmodimu

研究成果: ジャーナルへの寄稿記事

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We have used chains of Magnetic Data Acquisition System (MAGDAS) magnetometer records of the horizontal (H) and vertical (Z) magnetic field intensities during September 2008 to August 2009 (year of deep minimum) across Africa to study their variability during the quietest international days, which coincidently associated with the sudden stratospheric warming (SSW) event in January 2009. This selection of the most international quiet days is indicative of 80% that are strongly associated with days when unusually strong and prolonged sudden SSW event occurs in January 2009. Interestingly, in January, a significant magnitude depletion of solar quiet (Sq) equivalent current was observed near noon hours around the magnetic equator (Addis Ababa, ABB) compared to any other months along with a consistent significantly reduced value across the Northern Hemisphere and moderate decrease at the Southern Hemisphere. Also, we found that Nairobi and Dar es Salaam at the Southern Hemisphere, which are close to ABB (dip equator), are strongly prone to westward electric field compared to the magnetic equator and Khartoum at the Northern Hemisphere. Significant negative values of MSq(Z) magnitudes observed near noon hours at Hermanus indicate the presence of induced currents that suggest ocean effects along with reversal to significant positive values in the afternoon, which subsided before 1800-LT in almost all the months, indicate stronger influence of ionospheric currents. On seasonal variability of Sq(H), a slight depression at ABB during September equinox is one of the evidences of seasonal Sq focus shift. Latitudinal variability of Sq near-noon hours was also investigated. Key Points Abnormal intensification of electric currents Latitudinal sections of the African stations Highest and positive magnitude in February

元の言語英語
ページ(範囲)3883-3898
ページ数16
ジャーナルJournal of Geophysical Research: Space Physics
120
発行部数5
DOI
出版物ステータス出版済み - 5 1 2015

    フィンガープリント

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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