Spatial and temporal variations of the isotopic composition of precipitation over Thailand were investigated. The local meteoric water line for Thailand deviates slightly from the global meteoric water line, with lower slopes (7.62 ± 0.07, 7.59 ± 0.08) and intercepts (6.42 ± 0.39, 6.22 ± 0.42) using ordinary and precipitation weighted methods. Differences in spatial and temporal δ¹⁸O distributions between the tropical monsoon and tropical savanna climate zones were found due to differing moisture source contributions and seasonal precipitation patterns. The temporal data reveals that the northeast monsoon rains originate from isotopically‐enriched local moisture with isotope values of −9.36 to −0.09‰ (mean − 3.73 ± 0.42‰), whereas the southwest monsoon clouds had a more significant rainout effect from Rayleigh distillation, with isotope values of −9.56 to −1.78‰ (mean − 5.40 ± 0.38‰). The precipitation amount at each site was negatively correlated with δ¹⁸O (−0.24 to −3.20‰ per 100 mm, R² = 0.1–0.9). Furthermore, δ¹⁸O was negatively correlated with geography (latitude, altitude) for the southwest monsoon periods, as expected based on other observed correlations. However, an inverse correlation was seen in the northeast monsoon due to differing moisture transportation as part of the continental effect. The correlation coefficient (R) was higher in the southwest monsoon (−0.84 for latitude effect, −0.64 for altitude effect) than the northeast monsoon (0.67 for latitude effect, 0.35 for altitude effect). The spatial pattern of isotopic composition reflects the southwest monsoon more clearly than the northeast monsoon, but the two monsoons also have a cancelling impact on orographic patterns. An agreement of the δ¹⁸O and deuterium excess (d‐excess) was a negative correlation and found to reflect precipitation sources and re‐evaporation processes. The d‐excess was slightly higher for the northeast monsoon, bringing moisture from the Pacific Ocean and travelling across the continent before reaching the observed stations. By contrast, the d‐excess was relatively lower for the Indian Ocean's moisture in the southwest monsoon.

中文翻译：

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泰国降水中稳定同位素的时空分布

研究了泰国降水的同位素组成的时空变化。泰国的局部大气水线与全球大气水线略有不同，采用常规和降水加权方法，具有较低的坡度（7.62±0.07，7.59±0.08），并具有截距（6.42±0.39，6.22±0.42）。在空间和时间上的差异δ ¹⁸由于不同的水分源贡献和季节性降水模式，发现了热带季风和热带稀树草原气候带之间的O分布。时间数据表明，东北季风雨源来自同位素富集的局部水分，其同位素值为−9.36至-0.09‰（平均值为-3.73±0.42‰），而西南季风云的瑞利蒸馏具有更大的降雨效应，同位素值为-9.56至-1.78‰（平均值-5.40±0.38‰）。在每个站点的析出量呈负相关δ ¹⁸ O（-0.24到-3.20‰每100mm，R ² = 0.1-0.9）。此外，Δ ¹⁸根据其他观测的相关性，O与西南季风时期的地理（纬度，高度）呈负相关。然而，由于大陆活动的一部分不同的水分输送，在东北季风中发现了反相关。西南季风（纬度效应为-0.84，高度效应为-0.64）的相关系数（R）高于东北季风（纬度效应为0.67，高度效应为0.35）。同位素组成的空间模式比西南季风更清楚地反映了西南季风，但是这两个季风也对地形模式产生了抵消作用。该δ的协议，¹⁸ O和过量氘（d-过量）为负相关，并且发现反映了降水源和再蒸发过程。东北季风的d过量略高，从太平洋带入水分，并在到达观测站之前穿越整个大陆。相比之下，d建筑不动产是印度洋的西南季风湿度相对较低。