East Asian Monsoon Rainfall: Lessons from Four Decades of Field Campaigns

During the past four decades, a number of U.S.-Asia collaborative field campaigns have been carried out over the South China Sea that have focused on the study of East Asian monsoon circulations and rainfall: WMONEX (1978), TAMEX (1987), SCSMEX (1998), SoWMEXTiMREX (2008), and SCMREX (2013-18). These campaigns have yielded new insight into a wide range of phenomena and processes associated with East Asian monsoon: winter cold surges, the Borneo vortex, orographic effects, the Meiyu front, mesoscale convective systems, mesoscale convective vortices, the diurnal cycle, and SST gradients. The findings have contributed to steady improvements in monsoon prediction over this long time frame. Of particular interest has been the problem of extreme monsoon rainfall and it associated flooding in the neighboring countries of the South China Sea. There is growing concern over this issue as the climate warms.

This paper reviews past findings from field campaigns that bear on the problem of monsoon heavy rainfall and addresses key questions and challenges that remain.