Determination of the major moisture sources of cumulative effect of torrential rain events during the preflood season over South China using a Lagrangian particle model

Abstract

In this paper, reanalysis data collected by ERA‐Interim 4 times daily from 1979 to 2014 are used to analyze the main atmospheric moisture sources of cumulative effect of torrential rain (CETR) events during the preflood season (1 April to 30 June) over South China. Using a Lagrangian particle dispersion model—the Hybrid Single‐Particle Lagrangian Integrated Trajectory model—the major atmospheric moisture sources of 66 CETR events for the period of 1979–2014 are identified and compared. In this study, five atmospheric moisture sources—the land area, Indian Ocean, Pacific Ocean, South China Sea, and South China—are defined, and the effects of these moisture sources on preflood season CETR events over South China are quantitatively estimated. The results indicate that during the preflood season, Indian Ocean water vapor transport accounts for 30% of the atmospheric moisture generated in CETR events, thus dominating precipitation over South China. The water vapor transport from the land area (14%), western Pacific Ocean (10%), South China Sea (25%), and South China (20%) also play important roles in preflood season CETR events. Furthermore, a significant transition in water vapor transport occurred in the 1990s, during which water vapor transport from the Indian Ocean increased significantly, while water vapor transport from the western Pacific Ocean significantly declined. In addition, a significant positive anomaly in Pacific Ocean and South China Sea water vapor transport spurred CETR events in the east, while a significant positive anomaly in Indian Ocean water vapor transport facilitated CETR events in the west.

Effects of horizontal resolution and air–sea coupling on simulated moisture source for East Asian precipitation in MetUM GA6/GC2

“…Precipitation bias is further reduced with an increase in horizontal resolution (Fig. 3b), which is consistent with previous studies showing that the higher the horizontal resolution is, the more remote moisture is blocked by the Himalayas (Curio et al, 2015). On the other hand, the precipitation recycling ratio increases with horizontal resolution (Fig.…”

“…One the other hand, in winter, over midlatitude EA, the major moisture source is the vast Eurasian continent beneath the midlatitude westerly jet (van der Ent et al, 2010). On the Tibetan Plateau, due to the surrounding mountains, the major moisture source is the evaporation from the local land mass (Curio et al, 2015;van der Ent and Savennije, 2011;Zhang et al, 2017). Although more and more recent studies support the view that the land surface is the major moisture source for EA precipitation, exceptions have also been found.…”

The roles of moisture transports in intraseasonal precipitation during the preflood season over South China

“…The Lagrangian method can trace variations in specific air parcels over time based on positioning and meteorological elements. Thus, the Hybrid Single‐Particle Lagrangian Integrated Trajectory (HYSPLIT) model (Draxler and Hess, , ) has been extensively used to study global moisture transport processes (Brimelow and Reuter, ; Perry et al ., ; Sodemann and Stohl, ; van der Ent et al ., ; Drumond et al ., ; Jiang et al ., ; Sun and Wang, , ; Chu et al ., ; Pathak et al ., ). Brimelow and Reuter () simulated the trajectories of air parcels over the Mackenzie River during three torrential rain events and found that the Gulf of Mexico was the main water vapour source for those torrential rain processes.…”

Review comments on GMD-2020-104

“…You could briefly compare your findings with previous moisture source/transport diagnostic studies in East/Southeast Asia using Langragian models and reanalysis data (e.g. Sun and Wang, 2015;Baker et al 2015;Chu et al 2017).…”