Alleviated WRF Summer Wet Bias Over the Tibetan Plateau Using a New Cloud Macrophysics Scheme
Alleviated WRF Summer Wet Bias Over the Tibetan Plateau Using a New Cloud Macrophysics Scheme
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DOI：
10.1029/2023ms003616
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发表时间：
2023-10
影响因子：
6.8
通讯作者：
Dingchi Zhao;Yanluan Lin;W. Dong;Yi Qin;Wenchao Chu;Kun Yang;H. Letu;Lei Huang
中科院分区：
文献类型：
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作者：
Dingchi Zhao;Yanluan Lin;W. Dong;Yi Qin;Wenchao Chu;Kun Yang;H. Letu;Lei Huang
可靠的降水模拟在青藏高原（TP）仍然是一个挑战，表现在一个突出的系统性湿偏置在温暖的季节。以往的研究普遍忽略了地面辐射能量收支与降水偏差之间的潜在联系。夏季青藏高原上空的散射积云和雷暴对地面辐射有很强的影响。在WRF模式中实现了一个考虑次网格温度和湿度波动的云分数方案，并进行了为期一个月的模拟测试。结果发现，该方案更好地再现地面太阳辐射相比，默认的云分数方案在WRF模式。利用丰富的地面观测资料，我们发现高估地面向下短波辐射（DSSR）会导致湿偏差。DSSR的高估有助于更高的地面温度和更大的蒸发和增强的大气不稳定性，这有利于更多的模拟对流降水。研究表明，更好地模拟云和地面辐射将有利于高原降水模拟。
Reliable precipitation simulation over the Tibetan Plateau (TP) remains a challenge, manifested by a prominent systematic wet bias in the warm season. Previous studies have generally neglected the potential linkage between surface radiation energy budget and precipitation bias. Prevalent scattered cumulus and thunderstorms over the TP in summer strongly influence surface radiation. A cloud fraction scheme considering subgrid temperature and humidity fluctuations is implemented in the WRF model and tested for a month‐long simulation. It is found that the scheme better reproduces the surface solar radiation compared to a default cloud fraction scheme in the WRF model. Using abundant surface observations, we find that overestimation of the downward surface shortwave radiation (DSSR) would lead to wet bias. DSSR overestimation contributes to higher surface temperature and larger evaporation and enhanced atmospheric instability, which favor more simulated convective precipitation. The study suggests that a better simulation of clouds and surface radiation would benefit precipitation simulation over the plateau.