Thermospheric meridional winds measured by the middle and upper atmosphere radar
Thermospheric meridional winds measured by the middle and upper atmosphere radar
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中高层大气雷达测量的热层经向风
DOI：
10.1029/ja095ia06p07683
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发表时间：
1990
影响因子：
--
通讯作者：
S. Kato
中科院分区：
文献类型：
--
作者：
W. Oliver;S. Fukao;T. Takami;M. Yamamoto;T. Tsuda;Takuji Nakamura;S. Kato
我们利用日本中高层大气（MU）雷达在日本志贺市的F区电子密度和离子速度测量的全年和季节平均值来计算该地区的中性经向风。在自然界中，平均风是昼夜分明的。全年平均风向白天向极地方向吹，夜晚向赤道方向吹。白天最大风速接近10度，夜间最大风速在午夜达到。这与公认的全球环流的图景是一致的，全球环流是由风驱动的，基本上绕着地球从日侧太阳下点向夜侧太阳下点移动。对离子阻力的依赖表现为夜间较大的风和白天中午的速度最大值。在冬天，整个白天都是强烈的北风，而在夏天，风只在中午前的几个小时变成北风，然后在一天的剩余时间里转向南风。MU雷达风与文献中报道的其他中纬度地区关于风向转向的阶段和时间的大多数其他此类风结果一致。然而，MU雷达风的振幅通常比其他地方报告的振幅小1.5-2倍。我们没有看到低纬度地区午夜的南风减弱的迹象，也没有看到极地附近地区报告的夜间超过每秒200米的大风减弱的迹象。
We use full-year and seasonal averages of F region electron density and ion velocity measurements made by the Japanese middle and upper atmosphere (MU) radar in Shigaraki, Shiga, Japan, to compute the neutral meridional winds for this location. The average winds are highly diurnal in nature. The all-year average winds are poleward by day and equatorward by night. Maximum daytime winds are reached near 10 LT, and maximum nighttime winds are reached at midnight. This is consistent with the accepted picture of global circulation consisting of winds driven basically around the Earth from the dayside subsolar point toward the nightside antisubsolar point. Dependence on ion drag is seen in the form of larger nighttime winds and the prenoon daytime velocity maximum. In winter the winds are strongly northward for the entire daylight period, while in the summer the winds become northward for only a few hours before noon and then turn southward for the remainder of the day. The MU radar winds are consistent with the majority of other such wind results reported in the literature for other mid-latitude locations concerning the phases and times of wind direction turnings. The amplitudes of the MU radar winds, however, are generally smaller than the amplitudes reported elsewhere by a factor of 1.5–2. We see no trace of an abatement in the southward wind at midnight as seen at lower latitudes or of large winds exceeding 200 m/s in the nighttime as reported for locations near the polar regions.