South China Sea Annual Meeting 2023 (SCSAM)

137 / 2023-08-18 23:51:34

Changes of ENSO-Southeast Asian Rainfall Association Driven by Warmer Climate

ENSO,rainfall anomalies,CMIP6,Southeast Asia,Global Warming

El Niño-Southern Oscillation (ENSO) is the dominant inter-annual variabilities modulator for rainfall  over the Southeast Asia regions. However, how this modulation may be altered under future warmer climate is currently unknown. In current study, we examined the changes of ENSO associated winter rainfall anomalies in Southeast Asia (SEA) within the historical period (1981-2010) and also during the end of 21^st century (2071-2100) Coupled Model Inter-comparison Project Phase 6 (CMIP6) General Circulation Models (GCMs) simulations. During the historical period, ENSO had a significant negative association with Southeast Asia’s winter rainfall, particularly over Indochina mainland, Maritime Continent and northern Borneo. During the El Nino, the dry anomalies are largely associated with a low-level anticyclonic system driven subsidence over the western north Pacific (WNP). Under the SSP5-8.5 scenarios, the analysis outcome indicates the strengthening of the negative rainfall-ENSO teleconnection, toward the end of 21^st century. The anticyclonic system shifted slight northwestward and the downward motion expanded westward, and expanding the ENSO affected areas. The westward expansion of downward branch leads to the suppression of convective activities, causing the ’dry-getting-drier’ condition to occur. Overall, the outcome of the study indicates that ENSO will have a stronger influence on Southeast Asia atmospheric circulation and rainfall anomalies under a warmer climate toward the late-21^st century. This could have additional implications for future seasonal rainfall forecast over the Southeast Asian countries. This aspect will be discussed during the meeting presentation.