The influence of wind stress, temperature, and humidity gradients on evaporation from reservoirs
The influence of wind stress, temperature, and humidity gradients on evaporation from reservoirs
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风应力、温度和湿度梯度对水库蒸发的影响
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
I. Webster
中科院分区：
文献类型：
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作者：
S. Condie;I. Webster
本文首次利用大气边界层-水体耦合模式研究了取水受限水体的蒸发。该模式包含一个简化的大气边界层，其中热量和水分水平平流，垂直扩散。风场在水体上空通过内部边界层的形成而演变，内部边界层是由陆地到水面的粗糙度变化引起的。风还通过包含Monin - Obukhov相似函数来响应局部稳定性。该系统基于全热力学原始方程与动态活动水体耦合。这是通过空气-水界面的应力和热流的连续性来实现的。模型结果表明，风应力、湿度和温度的风向梯度都对蒸发有显著影响。最重要的影响是，当我们顺风穿过水体时，风的压力会增加，湿度会增加。然而，这些影响有相互抵消的趋势，因此其行为范围可以从非常光滑的陆地表面的实际平均蒸发随fetch而弱下降到相对粗糙的陆地地形的平均蒸发随fetch而弱增加。对于大多数感兴趣的情况，例如典型的农业环境，蒸发基本上与获取无关。所有模式的结果都总结为一个简单的蒸发量经验表达式，该表达式完全基于逆风陆地表面的气象数据。这与澳大利亚东南部一个小湖泊的详细测量结果非常吻合。
Evaporation from fetch‐limited water bodies has been investigated for the first time using a coupled atmospheric boundary layer–water body model. The model incorporates a simplified atmospheric boundary layer in which heat and moisture are advected horizontally and diffused vertically. The wind field evolves over the water body through the formation of an internal boundary layer, which is initiated by the change in roughness from the land to the water surface. The wind also responds to local stability through the inclusion of Monin‐Obukhov similarity functions. This system is coupled to a dynamically active water body based on primitive equations with full thermodynamics. This is achieved through continuity of stress and heat flux through the air‐water interface. The model results reveal that along‐wind gradients in wind stress, humidity, and temperature can all significantly influence evaporation. The most important effects are growing wind stress and increasing humidity as we move downwind across the water body. However, there is a tendency for these effects to cancel, so that the behavior can range from areally averaged evaporation weakly decreasing with fetch for very smooth land surfaces to weakly increasing with fetch for relatively rough land terrain. For most situations of interest, such as typical agricultural settings, evaporation is essentially independent of fetch. All the model results have been summarized in a simple empirical expression for evaporation based exclusively on meteorological data from over the upwind land surface. This is in good agreement with detailed measurements from a small lake in southeastern Australia.