Gravity waves in the mesosphere observed with the middle and upper atmosphere radar
Gravity waves in the mesosphere observed with the middle and upper atmosphere radar
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DOI：
10.1029/rs025i005p01005
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发表时间：
1990-09
期刊：
影响因子：
1.6
通讯作者：
T. Tsuda;S. Kato;T. Yokoi;T. Inoue;M. Yamamoto;T. Vanzandt;S. Fukao;Toru Sato
中科院分区：
文献类型：
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作者：
T. Tsuda;S. Kato;T. Yokoi;T. Inoue;M. Yamamoto;T. Vanzandt;S. Fukao;Toru Sato
1986年10月13日至31日白天（0800-1600LT）期间，我们利用中高层大气（MU）雷达观测到了60至90公里高度的风运动。在19天的观测中，有16天出现了具有相当正弦垂直结构的重力波。它们的特征是典型的垂直波长为 5-15 公里，固有周期约为 8.6 小时。这些波的传播速度是使用线性重力波理论确定的。所有波都向下传播，并具有经向传播的赤道分量。水平传播方向中值偏南偏东，平均水平相速度为35.3 m/s。中尺度风脉动水平分量的垂直波数谱与饱和重力波的理论谱非常吻合。在频率从 1 × 10−5 到大约 4 × 10−5 c/s 的频率下，垂直和径向风分量的频谱分别具有 1/3 和 −5/3 的对数斜率，这与模型重力波频谱非常吻合。多普勒频移对频谱的影响在布伦特维萨拉频率附近的大频率处最为明显。我们还测定了周期为10分钟至8小时的波浪引起的水平动量向上通量，并进一步估计了向西和向北的体力分别为5.1和4.0 m/s/d。
We have observed wind motions from 60 to 90 km altitudes with the middle and upper atmosphere (MU) radar during daylight hours (0800–1600 LT) from October 13 to 31, 1986. Gravity waves with fairly sinusoidal vertical structure were evident on 16 days of the 19 days of observations. They were characterized by a typical vertical wavelength of 5–15 km and intrinsic periods centered at about 8.6 hours. The propagation velocity of these waves was determined using the linear gravity wave theory. All of the waves propagated downward and had an equatorward component of the meridional propagation. The median direction of horizontal propagation was slightly east of south, and the mean horizontal phase speed was 35.3 m/s. The vertical wave number spectra of horizontal components of mesoscale wind fluctuations agree well with the theoretical spectrum of saturated gravity waves. At frequencies from 1 × 10−5 to about 4 × 10−5 c/s frequency spectra of vertical and radial wind components had logarithmic slopes of 1/3 and −5/3, respectively, which agree fairly well with a model gravity wave spectrum. The effects of Doppler shifting on frequency spectra are most obviously recognized at large frequencies near the Brunt Vaisala frequency. We have also determined the upward flux of horizontal momentum induced by waves with periods from 10 min to 8 hours and further estimated the westward and northward body force of 5.1 and 4.0 m/s/d, respectively.