Southeastern South America is influenced by moisture transport from lower latitudes, sustains intense convective storms and is a land–atmosphere coupling hotspot, but the interconnection between these processes is still not well understood. We present the warm‐season diurnal cycle climatology of the atmospheric water balance components in the South American Low‐Level Jet (SALLJ) exit region in northeastern Argentina during 1998–2012. Different precipitation‐based types of events (clear‐sky and rainy days) were explored together with processes tied to the land–atmosphere coupling at the daily scale. Our research was based on simulations with and without soil moisture–atmosphere coupling with the RCA4 regional climate model. A control simulation was compared with a sensitivity simulation where the soil moisture was prescribed with the daily climatological values from the control run. The ERA5 reanalysis and the satellite precipitation products TRMM‐3B42 v7 and CMORPH v1.0 bias‐corrected were used for comparative purposes. From the diurnal water balance analysis, we found that moisture flux convergence in the region is the main driver for nocturnal precipitation while local evapotranspiration feeds afternoon rain events. Rainy afternoons do not show differences between simulations, but rainy nights seem to be affected. Moreover, daily correlations between surface and boundary‐layer variables showed that the local coupling is weaker during rainy days than during clear‐sky days. Therefore, we suggest that changes in non‐local drivers, such as the moisture flux through the SALLJ, are more relevant for rainy nights than the local coupling.

中文翻译：

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阿根廷东北部的暖季降水驱动因素：大气水分平衡和陆-气耦合的昼夜循环

南美洲东南部受到低纬度地区水汽输送的影响，持续强烈的对流风暴，并且是陆地-大气耦合的热点，但是这些过程之间的相互联系仍然不清楚。我们介绍了1998-2012年阿根廷东北部南美低空急流（SALLJ）出口地区大气水平衡成分的暖季昼夜气候。探索了不同的基于降水的事件类型（晴空和雨天），以及与日尺度上陆地-大气耦合相关的过程。我们的研究基于有和没有土壤水分-大气的模拟以及RCA4区域气候模型。将对照模拟与灵敏度模拟进行比较，在该敏感性模拟中，根据对照运行的每日气候值来规定土壤湿度。为了进行比较，使用了ERA5重新分析和经过偏斜校正的卫星降水量TRMM-3B42 v7和CMORPH v1.0。通过昼夜水平衡分析，我们发现该地区的水分通量收敛是夜间降水的主要驱动力，而当地的蒸散作用则是下午降雨事件的源头。下雨的下午并没有显示模拟之间的差异，但是下雨的夜晚似乎受到了影响。此外，地表和边界层变量之间的日常相关性表明，雨天的局部耦合比晴空的时候弱。因此，我们建议更改非本地驱动程序，