Atmospheric moisture distribution and transport over the Tibetan Plateau and the impacts of the South Asian summer monsoon

In this study, by using the ECMWF ERA-Interim reanalysis data from 1979 to 2010, the spatial distribution and transport of total atmospheric moisture over the Tibetan Plateau (TP) are analyzed, together with the associated impacts of the South Asian summer monsoon (SASM). Acting as a moisture sink in summer, the TP has a net moisture flux of 2.59×107 kg s−1 during 1979–2010, with moisture supplies mainly from the southern boundary along the latitude belts over the Bay of Bengal and the Arabian Sea. The total atmospheric moisture over the TP exhibits significant differences in both spatial distribution and transport between the monsoon active and break periods and between strong and weak monsoon years. Large positive (negative) moisture anomalies occur over the southwest edge of the TP and the Arabian Sea, mainly due to transport of easterly (westerly) anomalies during the monsoon active (break) period. For the whole TP region, the total moisture supply is more strengthened than the climatological mean during the monsoon active period, which is mainly contributed by the transport of moisture from the south edge of the TP. During the monsoon break period, however, the total moisture supply to the TP is slightly weakened. In addition, the TP moisture sink is also strengthened (weakened) in the strong (weak) monsoon years, mainly attributed by the moisture transport in the west-east directions. Our results suggest that the SASM has exerted great impacts on the total atmospheric moisture and its transport over the TP through adjusting the moisture spatial distribution.