Spatiotemporal Variation of Water Vapor Budget over the Tibetan Plateau and Its Regulation on Precipitation

The spatiotemporal variations of water vapor budget (Bt) and their relationships with local precipitation over the Tibetan Plateau (TP) are critical for understanding the characteristics of spatial distributions and evolutions of water resources over the TP. Based on a boundary of the TP, this paper explored the spatiotemporal characteristics of Bt over the TP using the European Centre for Medium-Range Weather Forecasts interim (ERA-Interim) reanalysis datasets. On the climatological mean, the TP is a water vapor sink throughout four seasons and the seasonal variation of Bt is closely associated with the water vapor budget at the southern boundary of the TP. The transient water vapor transport is quasimeridional in the mid- and high-latitude areas and plays a leading role in winter Bt but contributes little in other seasons. At the interannual timescale, the variation of Bt is mainly determined by anomalous water vapor transports at the western and southern boundaries. The Bay of Bengal, the North Arabian Sea, and mid-latitude West Asia are the main sources of excessive water vapor for a wetter TP. At the southern and western boundaries, the transient water vapor budget regulates one-third to four-fifths of Bt anomalies. Moreover, the variability of the TP Bt is closely associated with precipitation over the central-southern and southeastern parts of the TP in summer and winter, which is attributed to the combined effect of the stationary and transient water vapor budgets. Given the role of the transient water vapor transport, the linkage between the TP Bt and local precipitation is tighter.