Katabatic flow mechanisms on a low-angle slope
Katabatic flow mechanisms on a low-angle slope
复制标题
DOI：
10.1175/jam-2182.1
复制
发表时间：
2005-01-01
期刊：
影响因子：
--
通讯作者：
Whiteman, CD
中科院分区：
文献类型：
--
作者：
Haiden, T;Whiteman, CD
本文重新讨论了斜面上下降流的动量和热量收支方程。这些方程中的条款进行评估，使用风和潜在的温度数据从四个系留气球数据收集系统上运行的一个3公里的线在犹他州的大盐湖山谷的Oqualeh山脚下的1.6度的斜坡。分析的重点是发展与下坡距离的下降流和相关的负浮力层天气原状条件下。强烈的环境分层，下降流显示站点之间的变化很小，这表明一个接近当地平衡的状态。当环境分层较弱时，两个系留探空仪站点之间的下降流的加速度系统地大于根据观测到的浮力所预测的速度。所观察到的流向与当地地形梯度的比较表明，坡度曲率，与小偏差，从基本上是平面的斜坡，可能是负责的异常增加。它的结论是，跨斜率的均匀性的流量，这是假设在简化的下降流模型，可能会显着干扰，甚至在斜坡上出现的平面观察员。
Momentum and heat budget equations for katabatic flows on sloping surfaces are revisited. Terms in these equations are evaluated using wind and potential temperature data from four tethered-balloon data collection systems on a 3-km line running down a 1.6degrees slope at the foot of the Oquirrh Mountains in Utah's Great Salt Lake valley. The analyses focus on the development with downslope distance of the katabatic flow and the associated negatively buoyant layer under synoptically undisturbed conditions. With strong ambient stratification, the katabatic flow shows little variation between sites, suggesting a state close to local equilibrium. When the ambient stratification is weaker, the acceleration of the katabatic flow between two tethersonde sites is systematically larger than what would be predicted based on observed buoyancy. Comparison of observed flow direction with the local topographic gradient indicates that slope curvature, associated with small deviations from the basically planar slope, may be responsible for the anomalous increase. It is concluded that the cross-slope homogeneity of the flow, which is assumed in simplified katabatic flow models, may be significantly disturbed even on slopes that appear to be planar to the observer.