The development and structure of nocturnal slope winds in a simple valley
The development and structure of nocturnal slope winds in a simple valley
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单纯河谷夜间坡风的发展与结构
DOI：
10.1007/bf00123177
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发表时间：
1990
影响因子：
4.3
通讯作者：
C. Whiteman
中科院分区：
文献类型：
--
作者：
J. Doran;T. W. Horst;C. Whiteman
本文介绍了一个简单山谷夜间坡风的观测和模拟研究结果。在测量区域，山谷约225米深，其一个侧壁的坡度约为23 °。用塔上仪器测量了山谷侧壁上下降气流的风和温度结构，并使用多普勒声雷达和系留气球和61米塔上的仪器来确定山谷中心附近的大气条件。用反演深度和反演强度的特征尺度参数h和δT表征了坡面流的温度结构。在谷底以上50米的侧壁上，反转深度一般较小，反转强度弱于100米以上的侧壁。这些结果显着不同，从一个孤立的山或山脊的简单的斜坡上获得的。山谷风被证明是重要的限制侧壁反转的强度。在山谷中的逆温的形成也有一个显着的影响，斜坡流的结构。数值模拟表明，在山谷大气中的绝热层的存在与斜坡流逆温深度随下坡距离的增加而减小有关。模拟还表明，长度尺度的特征的动量和反演深度的行为相似，在流下来简单的斜坡，但不是在流下来的侧壁的一个山谷。
The results of an observational and modeling study of the nocturnal slope winds in a simple valley are presented. The valley was approximately 225 m deep in the region of the measurements, and featured a uniform slope angle of approximately 23 ° on one of its sidewalls. The wind and temperature structure of the katabatic flows on the valley sidewalls were measured with tower-mounted instruments, and a Doppler sodar and instruments on a tethered balloon and a 61-m tower were used to determine the atmospheric conditions near the center of the valley. The temperature structure of the slope flows was summarized by characteristic scale parameters h and δT for the inversion depth and strength, respectively. On the sidewalls 50 m above the valley floor, the inversion depths were generally smaller and the inversion strengths were weaker than they were on the sidewalls 100 m higher. These results differ significantly from those obtained over a simple slope of an isolated mountain or ridge. The down-valley winds are shown to be important in limiting the strength of the sidewall inversions. The formation of an inversion in the valley also has a pronounced effect on the structure of the slope flows. Numerical simulations suggest that the presence of adiabatic layers in the valley atmosphere is associated with decreases in the slope-flow inversion depth with increasing downslope distance. The simulations also indicate that the length scales that characterize the momentum and inversion depths behave similarly in flows down simple slopes but not in flows down the sidewalls of a valley.