The stable isotopes (δ¹⁸O and δD) of water vapor are used to characterize continuous variations in large-scale and boundary-layer atmospheric processes. We presented continuous measurements of δ¹⁸O in surface water vapor at Lhasa, southern Tibetan Plateau, from October 2018 to September 2019 to investigate how large-scale and local atmospheric processes influence variations in water vapor δ¹⁸O at different time scales. The water vapor δ¹⁸O measurements reveal different seasonal characteristics and diurnal patterns. At the seasonal scale, δ¹⁸O exhibits a W-shape with two maxima in May–June and October as well as two minima in July–August and February. The diurnal variations in the water vapor δ¹⁸O and meteorological data throughout the year present distinct occurrences of maxima and minima during different periods. We found that the significant seasonal variability is mainly associated with the transition between the Indian summer monsoon and the westerlies, which transport distinct moisture to the southern Tibetan Plateau. The local temperature, specific humidity and boundary layer height impact the diurnal variations in water vapor δ¹⁸O to some extent with remarkable seasonal differences.

水蒸气的稳定同位素（δ ¹⁸ O 和 δD）用于表征大规模和边界层大气过程中的连续变化。我们展示了2018 年 10 月至 2019 年 9 月对青藏高原南部拉萨地表水汽中 δ ¹⁸ O 的连续测量，以研究大尺度和局地大气过程如何影响不同时间尺度下水汽 δ ¹⁸ O 的变化。水蒸气 δ ¹⁸ O 测量揭示了不同的季节特征和昼夜模式。在季节性尺度上，δ ¹⁸ O 呈 W 形，在 5-6 月和 10 月有两个最大值，在 7-8 月和 2 月有两个最小值。水汽的日变化δ ¹⁸全年的 O 和气象数据在不同时期呈现出不同的最大值和最小值。我们发现显着的季节性变化主要与印度夏季风和西风之间的过渡有关，西风将明显的水分输送到青藏高原南部。局地温度、比湿和边界层高度对水汽δ ¹⁸ O的日变化有一定的影响，具有显着的季节差异。