Abstract
The Tibetan Plateau (TP), atmosphere, and Indo-Pacific warm pool (IPWP) together constitute a regional land–atmosphere–ocean water vapor transport system. This study uses remote sensing data, reanalysis data, and observational data to explore the spatiotemporal variations of the summer atmospheric water cycle over the TP and its possible response to the air-sea interaction in the IPWP during the period 1958–2019. The results reveal that the atmospheric water cycle process over the TP presented an interannual and interdecadal strengthening trend. The climatic precipitation recycle ratio (PRR) over the TP was 18%, and the stronger the evapotranspiration, the higher the PRR. On the interdecadal scale, the change in evapotranspiration has a significant negative correlation with the Pacific Decadal Oscillation (PDO) index. The variability of the water vapor transport (WVT) over the TP was controlled by the dynamic and thermal conditions inside the plateau and the external air-sea interaction processes of the IPWP. When the summer monsoon over the TP was strong, there was an anomalous cyclonic WVT, which increased the water vapor budget (WVB) over the TP. The central and eastern tropical Pacific, the maritime continent and the western Indian Ocean together constituted the triple Sea Surface Temperature (SST) anomaly, which enhanced the convective activity over the IPWP and induced a significant easterly wind anomaly in the middle and lower troposphere, and then generated pronounced easterly WVT anomalies from the tropical Pacific to the maritime continent and the Bay of Bengal. Affected by the air-sea changes in the IPWP, the combined effects of the upstream strengthening and the downstream weakening in the water vapor transport process, directly and indirectly, increased the water vapor transport and budget of TP.
Highlights
Water plays a vital role in maintaining the stability of ecosystems and social systems; in the context of global warming, the evolution of the regional water resources pattern and the water cycle under high mountain conditions show more significant response characteristics [1,2]
Under the background of thermal and dynamic effects caused by complex topographic features, the water vapor transport (WVT) and water cycle system of Tibetan Plateau (TP) are different from other regions at the same latitude, making the TP an important bridge connecting the landatmosphere-ocean system in the northern hemisphere [5,6]
600 hPa in summer, and the Div_PMI was reversed to obtain Neg(Div_PMI), which means that the greater the positive value, the stronger the TP summer monsoon (TPSM)
Summary
Water plays a vital role in maintaining the stability of ecosystems and social systems; in the context of global warming, the evolution of the regional water resources pattern and the water cycle under high mountain conditions show more significant response characteristics [1,2]. The Tibetan Plateau (TP), known as the “Asian Water Tower,” stores a large amount of freshwater resources (lakes, glaciers, snow, etc.) but is the birthplace of many rivers, and its water cycle is sensitive to the climate change [3,4]. For the plateau terrestrial water cycle, the accelerated melting and degradation of glaciers, degradation of permafrost, and significant expansion of lakes have jointly regulated the land water balance of many local and downstream rivers [2,10,11]. Examining the evolution characteristics of the atmospheric water cycle of the TP provides indispensable theoretical support for revealing the evolution of the hydrological system of the TP and has great practical significance for the scientific utilization of water resources [14,15]
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