An explicit prognostic cloud‐cover scheme (PROGCS) is implemented into the Global/Regional Assimilation and Prediction System (GRAPES) for global middle‐range numerical weather predication system (GRAPES_GFS) to improve the model performance in simulating cloud cover and radiation. Unlike the previous diagnostic cloud‐cover scheme (DIAGCS), PROGCS considers the formation and dissipation of cloud cover by physically connecting it to the cumulus convection and large‐scale stratiform condensation processes. Our simulation results show that clouds in mid‐high latitudes arise mainly from large‐scale stratiform condensation processes, while cumulus convection and large‐scale condensation processes jointly determine cloud cover in low latitudes. Compared with DIAGCS, PROGCS captures more consistent vertical distributions of cloud cover with the observations from Atmospheric Radiation Measurements (ARM) program at the Southern Great Plains (SGP) site and simulates more realistic diurnal cycle of marine stratocumulus with the ERA‐Interim reanalysis data. The low, high, and total cloud covers that are determined via PROGCS appear to be more realistic than those simulated via DIAGCS when both are compared with satellite retrievals though the former maintains slight negative biases. In addition, the simulations of outgoing longwave radiation (OLR) at the top of the atmosphere (TOA) from PROGCS runs have been considerably improved as well, resulting in less biases in radiative heating rates at heights below 850 hPa and above 400 hPa of GRAPES_GFS. Our results indicate that a prognostic method of cloud‐cover calculation has significant advantage over the conventional diagnostic one, and it should be adopted in both weather and climate simulation and forecast.

中文翻译：

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显式预后云覆盖方案在GRAPES全球预报系统中的应用和评估

为全球中距离数值天气预报系统（GRAPES_GFS），在全球/区域同化和预测系统（GRAPES）中实现了显式的预后云覆盖方案（PROGCS），以提高模拟云层覆盖和辐射的模型性能。与以前的诊断云覆盖方案（DIAGCS）不同，PROGCS通过将其物理连接到积云对流和大规模层状凝结过程来考虑云层的形成和消散。我们的模拟结果表明，中高纬度的云主要来自大规模的层状凝结过程，而积云对流和大规模的凝结过程共同决定了低纬度的云层。与DIAGCS相比，PROGCS利用南部大平原（SGP）站点的大气辐射测量（ARM）程序的观测结果，捕获了更一致的云层垂直分布，并使用ERA-中期再分析数据模拟了更真实的海洋平积层日循环。当将两者与卫星取回进行比较时，通过PROGCS确定的低，高和总云量似乎比通过DIAGCS模拟的云量更现实，尽管前者保持轻微的负偏差。此外，PROGCS运行在大气层顶部（TOA）发出的长波辐射（OLR）的模拟也得到了显着改善，从而在GRAPES_GFS高度低于850 hPa和高于400 hPa时，降低了辐射加热速率的偏差。 。