Stream temperature studies typically use either the Penman combination equation (PCE) or empirical wind functions to compute the latent heat flux, which can be an important control on daily maximum water temperature. The sensible heat flux is usually computed from the latent heat flux via the Bowen ratio or a bulk transfer model. Unfortunately, both the PCE and empirical wind functions involve challenges. The PCE is inappropriate for application to subdaily stream evaporation because, as implemented in many stream temperature studies, it does not account for energy associated with warming or cooling of the water column or bed heat fluxes. The PCE thus tends to overestimate evaporation under conditions typical of warm summer days during the diurnal warming phase, which is when evaporation is likely to be an important heat loss mechanism. Empirical wind functions involve substantial uncertainty given the broad range of coefficient values that have been reported in the literature and the lack of above‐stream meteorological data to use in their application. We provide suggestions for improving current practice and also identify research directions to support development of robust approaches to computing the latent and sensible heat fluxes.

中文翻译：

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预测河流温度模型中的潜热通量和感热通量：当前的挑战和潜在的解决方案

溪流温度研究通常使用Penman组合方程（PCE）或经验风函数来计算潜热通量，这可能是每日最高水温的重要控制。显热通量通常是通过Bowen比或体传递模型从潜热通量计算得出的。不幸的是，PCE和经验风功能都涉及挑战。PCE不适合应用于次日流蒸发，因为正如许多流温度研究中所实施的那样，PCE并未考虑与水柱或床热通量的增温或降温相关的能量。因此，PCE倾向于在昼夜升温阶段典型的温暖夏季条件下高估蒸发量，这时蒸发很可能是重要的热量散失机制。考虑到文献中已经报道了广泛的系数值，并且缺乏在其应用中使用的上游气象数据，经验性风函数具有很大的不确定性。我们提供了改善当前实践的建议，并确定了研究方向，以支持开发强大的方法来计算潜热通量和显热通量。