Recent changes in the moisture source of precipitation over the Tibetan Plateau

• Various evidences have suggested a wetting trend over part of the Tibetan Plateau (TP) in recent decades, although there is still large uncertainty in the change trend of precipitation due to sparse observations. Examining change in moisture source for precipitation over a region in the TP with most obvious increasing precipitation trend may help understand the precipitation change. This study applied the modified Water Accounting Model with two atmospheric reanalyses, ground-observed precipitation, and evaporation from land surface model to investigate the change in moisture source of the precipitation over the targeted region. We estimated that on average more than 69% and more than 21% of the moisture supply to the precipitation over the targeted region came from land and ocean respectively. The moisture transports from the West of the TP by the westerlies and from the Southwest by the Indian summer monsoon likely contributed the most to the precipitation over the targeted region. The moisture from inside the region may have contributed to about 18% of the total precipitation. Most of the increased moisture supply to the precipitation during 1979-2013 was attributed to the enhanced influx from the Southwest and the local moisture supply. The precipitation recycling ratio over the targeted region increased significantly, suggesting an intensified hydrological cycle. Further analysis at monthly scale and with wet-dry year composites indicates that the increased moisture contribution was mainly from the Southwest and the targeted region during May and September. The enhanced water vapor transport from the Indian Ocean during July and September and the intensified local hydrological recycling seem to be the primary reasons behind the recent precipitation increase over the targeted region.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)