The aerodynamic roughness length is a crucial parameter that controls surface variables including the horizontal wind, surface temperature, and heat fluxes. Despite its importance, in the Weather Research and Forecasting (WRF) model, this parameter is typically assigned a predefined value, mostly based on the dominant land‐use type. In this work, the roughness length is first estimated from eddy‐covariance measurements at Al Ain in the United Arab Emirates (UAE), a hyper‐arid region, and then ingested into WRF. The estimated roughness length is in the range 1.3–2.2 mm, one order smaller than the default value used in WRF. In line with previous studies, and from WRF model simulations during the warm and cold seasons, it is concluded that, when the roughness length is decreased by an order of magnitude, the horizontal wind speed increases by up to 1 m s⁻¹, the surface temperature rises by up to 2.5°C, and the sensible heat flux decreases by as much as 10 W m⁻². In comparison with in situ station and eddy covariance data, and when forced with the updated roughness length, WRF gives more accurate 2‐m air temperature and sensible heat flux predictions. For prevailing wind speeds >6 m s⁻¹, the model underestimates the strength of the near‐surface wind, a tendency that can be partially corrected, typically by 1–3 m s⁻¹, when the updated roughness length is considered. For low wind speeds (<4 m s⁻¹), however, WRF generally overestimates the strength of the wind.

中文翻译：

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粗糙度对高干旱地区WRF模拟的陆-气相互作用的影响

空气动力学粗糙度长度是控制表面变量（包括水平风，表面温度和热通量）的关键参数。尽管有其重要性，但在“天气研究与预报（WRF）”模型中，通常会为该参数分配一个预定义的值，主要是基于主要的土地利用类型。在这项工作中，首先从超干旱地区阿拉伯联合酋长国（UAE）的艾因市的涡度协方差测量中估算出粗糙度长度，然后将其摄入WRF。估计的粗糙度长度在1.3–2.2 mm范围内，比WRF中使用的默认值小一个数量级。与以前的研究相一致，并且根据暖和冷季节的WRF模型模拟得出的结论是，当粗糙度长度减小一个数量级时，^-1，表面温度最高升高2.5°C，显热通量降低多达10 W m ^-2。与原位测站和涡流协方差数据相比，当使用更新的粗糙度长度进行强制测量时，WRF可以提供更精确的2 m气温和合理的热通量预测。对于> 6 m s ^-1的主要风速，该模型低估了近地表风的强度，当考虑更新的粗糙度长度时，该趋势可以部分校正，通常为1-3 m s ^-1。但是，对于低风速（<4 m s ^-1），WRF通常会高估风的强度。