• 作者： 林崇安
• 作者服務機構： 國立中央大學大氣物理研究所
• 中文摘要： 本研究在於解釋地磁低緯地區微脈動之早晨黃昏不對稱性之觀測結果。本文先利用CGL原理，導出在非均勻之磁場、質量密度、非均向性壓力下，產生在磁層邊界層處非均向磁性流體之速度切不穩定性。由頻散方程式中，計算出波之滋長率。黏滯效應暫不考慮進去。由計算得知，快速磁聲波之滋長率，會隨速度切之增大而增大。由於磁層邊界層之早晨部位之速度切比黃昏部位為大，因此，依照本模式之結果，在早晨部位之快速磁聲波會比黃昏部位的滋長大。當這些波由邊界層傳至地球低緯地區後，自然會形成早晨及黃昏間微脈動之不對稱性。
• 英文摘要： Dawn-dusk asymmetry of the micropulsation observed in geomagnetic low-latitude areas is explainedby this study. We consider the generation of anisotropic hydromagnetic instability driven by velocity shearin the magnetospheric boundary layer by using Chew-Goldberger-Low (CGL) theory. A dispersion relationwith nonuniform magnetic field (x), mass density (x), anisotropic pressure and bulk flow velocity withstrong shear (x) is derived. The viscosity effect is neglected in the present model. Numerical calculationshows that the growth rate of the fast magnetosonic wave increases when the velocity shear increases.Based on the fact that the velocity shear of the plasma flow in the dawnside boundary layer is larger thanthat in the duskside boundary layer, therefore, the growth rate of the fast magnetosonic wave in the dawn-side is larger than that in the duskside according to our model. When these waves propagate from theboundary layers to the geomagnetic low-latitude areas, dawn-dusk asymmetry of the micropulsation isanticipated which agrees with observation.
• 中文關鍵字： micropulsation; velocity shear instability; CGL theory; magnetosPheric low-latitude boundary Iayer
• 英文關鍵字： --