Abstract This study investigated the sensitivity of the western North Pacific (WNP) summer precipitation to the convection schemes and discussed the associated dynamical processes. Two convection schemes were compared: one is the default mass-flux convection scheme used in the state-of-the-art ECHAM6.3 atmosphere model and the other incorporates the Stochastic Multicloud Model (SMCM) into ECHAM6.3. Incorporation of the SMCM reduces the bias of cloud cover and shortwave and longwave radiation by regulating the shortwave and longwave cloud radiative forcing over the WNP. Compared to the default model, the modified model with the SMCM alleviates the dry bias in the WNP, which is associated with enhanced ascending motion. The moist static energy balance revealed that improved simulation of precipitation in the modified model is contributed by enhanced horizontal advection of moist enthalpy and increased net energy in the atmosphere, which is attributed to increased total cloud cover, over the WNP. Additionally, intensified latent energy advection over the WNP dominates enhanced horizontal advection of moist enthalpy in the modified model. On the other hand, the moisture budget analysis of the WNP demonstrated that strengthened convergence of moisture flux in the modified model plays the most influential role in reducing precipitation bias. Further analysis unraveled that enhanced zonal-mean moisture transported by the stationary eddy zonal flow convergence in the WNP dominates intensified zonal moisture convergence, thus increased horizontal convergence of moist flux in the modified model.

中文翻译：

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随机多云参数化对西北太平洋夏季降雨模拟的影响

摘要 本研究调查了西北太平洋 (WNP) 夏季降水对对流方案的敏感性，并讨论了相关的动力过程。比较了两种对流方案：一种是最先进的 ECHAM6.3 大气模型中使用的默认质量通量对流方案，另一种是将随机多云模型 (SMCM) 纳入 ECHAM6.3。SMCM 的结合通过调节 WNP 上的短波和长波云辐射强迫来减少云覆盖和短波和长波辐射的偏差。与默认模型相比，带有 SMCM 的修改模型减轻了 WNP 中的干偏差，这与增强的上升运动相关。湿静态能量平衡表明，改进的模型中降水模拟的改进是由于湿焓的水平平流增强和大气中净能量的增加，这归因于西北部的总云量增加。此外，在修改后的模型中，WNP 上增强的潜能平流支配了增强的湿焓水平平流。另一方面，WNP的水分收支分析表明，修正模型中加强水分通量的收敛对减少降水偏差起着最有影响的作用。进一步的分析表明，西北部的静止涡旋纬向流汇聚所输送的纬向平均水分增强主导了纬向水汽汇聚的强化，