Understanding spatiotemporal variations in stable isotopes in precipitation (ẟO and ẟD) on the south slope of the Himalayas is crucial for comprehending moisture variations reaching the Tibetan Plateau (TP). Here, we analyze these variations at seven stations in Nepal spanning altitudes from 102 m to 5050 m above sea level in 2017. Our findings show no significant temperature or precipitation amount effect on isotopes, with synoptic precipitation exerting a strong influence. Non-monsoon precipitation primarily originates from the vicinity of the Koshi River basin and the Ganges River, while during the monsoon, the Bay of Bengal, the Koshi River basin, and the Ganges River contribute, with minimal input from the Arabian Sea. Convective activities significantly regulate inner-seasonal precipitation δO, with strong convection associated with low isotopic values. Increasing altitude leads to substantial differences in δO values, indicating modulation by higher condensation levels and lower temperatures. These findings underscore the impact of regional moisture transport on precipitation isotopic variability and offer insights into interpreting paleo-isotope records in the Indian Summer Monsoon region.

中文翻译：

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喜马拉雅南坡水汽输送过程对降水稳定同位素组成的影响


了解喜马拉雅山南坡降水稳定同位素（ẟO 和 ẟD）的时空变化对于了解到达青藏高原 (TP) 的水分变化至关重要。在这里，我们分析了 2017 年尼泊尔海拔 102 m 至 5050 m 的七个站点的这些变化。我们的研究结果表明，温度或降水量对同位素没有显着影响，天气降水产生了强烈影响。非季风期降水主要来自科西河流域和恒河附近地区，季风期间则主要来自孟加拉湾、科西河流域和恒河，阿拉伯海的输入量很少。对流活动显着调节内季节降水 δ18O，强对流与低同位素值相关。海拔升高会导致 δ18O 值显着差异，表明较高的凝结水平和较低的温度进行了调节。这些发现强调了区域水分输送对降水同位素变异的影响，并为解释印度夏季季风地区的古同位素记录提供了见解。