Regional Climate-Weather Research and Forecasting model (CWRF) simulations driven by the ECMWF-Interim reanalysis (ERI) showed that cumulus parameterization significantly impacts daily 95th percentile precipitation (P95) over the US Gulf States (GS) and Central-Midwest States (CM). This study compared interannual variations across ERI and five CWRF cumulus parameterization members based on CM and GS regional mean composites during P95 events. A structural equation model framework was used to build regressions of these variations among optimally selected fields to identify the underlying processes affecting P95. We discovered five distinct physical mechanisms, each involving unique interplays among water and energy supplies and surface and cloud forcings, with varying degrees of relative importance (%). In CM summer and CM and GS autumn, water supply (~ 60%), energy supply (~ 20%), and cloud forcing (~ − 20%) jointly determined P95. In GS spring and winter, surface forcing was predominant (84–87%), while energy and water supplies evenly accounted for the remaining impact. In CM spring, surface forcing was also predominant (85%), but was accompanied by energy supply alone. In GS summer, cloud forcing was predominant (− 84%), while water supply had the opposite impact (− 8%) to energy supply (6%). In CM winter, water supply (− 62%) also counteracted energy supply (31%) while cloud forcing played a positive role (7%). The seasonal reversal in the roles of water supply and cloud forcing occurred because the prevailing precipitation system changed from convective to stratiform processes. The choice of cumulus parameterization affected how water and energy supplies acted through surface and cloud forcings, thus determined CWRF’s ability to simulate extreme precipitation.

由ECMWF中期再分析（ERI）驱动的区域气候-天气研究和预报模型（CWRF）模拟显示，积云参数化显着影响美国墨西哥湾州（GS）和中西部地区（CM）的每日95％百分率降水（P95） ）。这项研究比较了P95事件期间基于CM和GS区域均值组合的ERI和五个CWRF积云参数化成员的年际变化。使用结构方程模型框架来构建最佳选择字段之间的这些变异的回归，以识别影响P95的潜在过程。我们发现了五种不同的物理机制，每种机制都涉及水和能源供应以及地表和云层强迫之间的独特相互作用，并具有不同程度的相对重要性（％）。在CM夏季，CM和GS秋季，供水（〜60％），能源供应（〜20％）和强迫云（〜-20％）共同决定了P95。在GS春季和冬季，地表强迫是主要因素（84-87％），而能量和水的供应则是造成其余影响的平均原因。在CM弹簧中，表面强迫也占主导地位（85％），但仅靠能量供应。在GS夏季，强迫云占主导地位（-84％），而供水对能源供应（6％）的影响相反（-8％）。在CM冬季，供水（-62％）也抵消了能源供应（31％），而强迫云起到了积极作用（7％）。由于主要的降水系统从对流过程转变为层状过程，因此发生了供水和云强迫作用的季节性逆转。