Spatial distribution of oceanic moisture contributions to precipitation over the Tibetan Plateau

[摘要] Evaporation from global oceans is an important moisturesource for glaciers and headwaters of major Asian rivers in the TibetanPlateau (TP). Although the accelerated global hydrological cycle, thealtered sea–land thermal contrast and the amplified warming rate over theTP during the past several decades are known to have profound effects on theregional water balance, the spatial distribution of oceanic moisturecontributions to the vast TP remains unclear. This hinders the accuratequantification of regional water budgets and the reasonable interpretationof water isotope records from observations and paleo archives. Based onhistorical data and moisture tracking, this study systematically quantifiesthe absolute and relative contributions of oceanic moisture to long-termprecipitation in the TP. Results show that the seasonal absolute andrelative oceanic contributions are generally out of phase, revealing thepreviously underestimated oceanic moisture contributions brought by thewesterlies in winter and the overestimated moisture contributions from theIndian Ocean in summer. Quantitatively, the relative contribution ofmoisture from the Indian Ocean is only ∼30  % in the southTP and further decreases to below 10 % in the northernmost TP. Theabsolute oceanic contribution exhibits a spatial pattern consistent with thedipole pattern of long-term precipitation trends across the BrahmaputraCanyon region and the central-northern TP. In comparison, relative oceaniccontributions show strong seasonal patterns associated with the seasonalityof precipitation isotopes across the TP.

[学科分类] 妇产科学