Roles of water vapor sources and transport in the intraseasonal and interannual variation in the peak monsoon rainfall over East China

Abstract

ERA-Interim reanalysis data from 1979-2017 are utilized to analyze the intraseasonal and interannual variabilities in the moisture transport associated with the summer rainfall over East China. Three key issues of moisture sources for East China summer precipitation are discussed in this study: the identi cation of the primary moisture sources of summer precipitation, determination of their individual contributions to the intraseasonal variation in summer precipitation, and determination of the extent to which each source affects the interannual variation in precipitation during the peak monsoon rainfall period (PMRP). Through the Lagrangian method, the water vapor is divided into six sources, namely, the land area source (LD source), East China source (EC source, except for the target region), Indian Ocean source (IO source), Paci c Ocean source (PO source), South China Sea source (SCS source), and regional evapotranspiration sources. This study proposes that the rainfall over South China (SC) during the PMRP is mainly in uenced by the IO source water vapor transport (52.4%). For the middle and lower Yangtze River valley (YRV), the rainfall contribution from southwesterly moisture transport accounts for approximately 50% of the total rainfall during the PMRP and determines the intraseasonal and interannual variation in the summer rainfall. The water vapor from terrestrial evaporation, which includes EC source water vapor (38.9%) and NC source water vapor (21.8%), is the most important moisture source for rainfall over North China (NC) during the PMRP.

Changes of extreme precipitation in the middle and lower reaches of the Yangtze River and their correlation with atmospheric circulation

“…Research indicates that precipitation in the MLYR is closely linked to the Western Pacific Subtropical High (WPSH) and the South China Sea high (SCSH). The South China Sea serves as one of the sources of water vapor for MLYR, transporting it to eastern China through the summer monsoon (Que et al, 2016;Chu et al, 2021). Additionally, the location of WPSH highly affects precipitation in the MLYR by controlling the position of the precipitation belt and transporting water vapor along the edge of the subtropical high (Tian et al, 2000).…”

Spatial-temporal variations of extreme precipitation indices and their linkage with atmospheric circulation in the middle and lower reaches of the Yangtze River

“…Similar patterns exist between R95 and SCSHI, and most of the arrows point to the upper right, indicating that R95 is positively correlated with the SCSH and lags behind the change of the SCSH. The WPSH and SCSH mainly affect the transport and convergence of water vapor (Chu et al, 2021;He et al, 2021). The South China Sea summer monsoon carries a large amount of water vapor, which opens the water vapor channels from the Indian Ocean through the Indian Peninsula, the Bay of Bengal, the Indo-China Peninsula and the South China Sea, and the southwest airflow continuously conveys water vapor northward along the periphery of the WPSH to MLYR (Tian et al 2000).…”

“…Studies have shown that precipitation in the MLYR is closely related to the Western Pacific Subtropical High (WPSH) and the South China Sea high (SCSH). As one of the sources of water vapor in the MLYR, the South China Sea conveys water vapor to eastern China through the South China Sea summer monsoon, Indian summer monsoon and East Asian summer monsoon (Chu et al, 2021;Que et al, 2016). Meanwhile, the precipitation in the MLYR is highly affected by the location of WPSH as WPSH controls the precipitation belt position and transportation of water vapor along the edge of the subtropical high (Tian et al, 2000).…”

Energy and Water Cycles in the Third Pole

“…Using the Lagrangian method, Jiang et al ( 2013) studied the characteristics of the moisture contributions during the boreal summer over the Yangtze River valley (YRV) [27]. Chu et al (2021) focused on the effect of water vapor transport processes on the variations in the seasonal mean rainfall over East China [28]. Chen and Luo (2018) used the Lagrangian model to explore the paths and sources of the water vapor carried to Southern China (SC) during the pre-flood season [29].…”