Summertime atmospheric water vapor transport between Tibetan Plateau and its surrounding regions during 1990-2019: Boundary discrepancy and interannual variation

The summertime atmospheric water vapor transport (WVT) of the Tibetan Plateau (TP) and surrounding regions is investigated based on the ERA5 reanalysis data during 1990-2019. It is found that the ascending motion on the south of the TP is conducive to the transport of water vapor from the low-latitude monsoon regions to the TP, showing strong WVT at 500 hPa on the southern TP. Strong water vapor transporting into the TP exists on the southern boundary (B-s) which is from Kashmir to the trumpet-shaped topography (TST) region, and from upper to lower layers. The WVT of the other three boundaries exhibit differently: (1) The prevailing westwards WVT exists on the western boundary. (2) The water vapor flows into the TP below 700 hPa on the Sichuan Basin and transports away from the TP above 700 hPa on the eastern boundary. (3) A regular water vapor flows out of into-out of the TP pattern is found on the northern boundary. The most active water vapor transporting towards the TP appears on the Sichuan Basin, TST and eastern Bs in the lower layer, while the most active water vapor transporting away from the TP occurs on the eastern boundary and middle-east Bs in the middle layer. In general, water vapor inflows of the TP are larger than its outflows, resulting in summertime TP becoming a water vapor sink (153.28 x 10(6) kg s(-1)). The result is mainly attributed to the water vapor inflows in the middle-lower layer on the Bs. The WVB and PW over the summer TP present the increasing trends during the recent years and the trend of the PW is significant.

Automated summary

The study on summertime atmospheric water vapor transport in the Tibetan Plateau and surrounding regions from 1990 to 2019 based on ERA5 reanalysis data revealed that the southern boundary is the main entry point for water vapor from low-latitude monsoon regions, with significant water vapor transport into regions like Sichuan Basin, TST and eastern boundary. The overall trend indicates that water vapor inflows into the Tibetan Plateau are greater than outflows, making it a water vapor sink during the summertime.