Assessing Future Changes in the East Asian Summer Monsoon Using CMIP5 Coupled Models

Abstract

Future changes in the East Asian summer monsoon (EASM) are estimated from historical and Representative Concentration Pathway 6.0 (RCP6) experiments of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The historical runs show that, like the CMIP3 models, the CMIP5 models produce slightly smaller precipitation. A moisture budget analysis illustrates that this precipitation deficit is due to an underestimation in evaporation and ensuing moisture flux convergence. Of the two components of the moisture flux convergence (i.e., moisture convergence and horizontal moist advection), moisture convergence associated with mass convergence is underestimated to a greater degree. Precipitation is anticipated to increase by 10%–15% toward the end of the twenty-first century over the major monsoonal front region. A statistically significant increase is predicted to occur mostly over the Baiu region and to the north and northeast of the Korean Peninsula. This increase is attributed to an increase in evaporation and moist flux convergence (with enhanced moisture convergence contributing the most) induced by the northwestward strengthening of the North Pacific subtropical high (NPSH), a characteristic feature of the future EASM that occurred in CMIP5 simulations. Along the northern and northwestern flank of the strengthened NPSH, intensified southerly or southwesterly winds lead to the increase in moist convergence, enhancing precipitation over these areas. However, future precipitation over the East China Sea is projected to decrease. In the EASM domain, a local mechanism prevails, with increased moisture and moisture convergence leading to a greater increase in moist static energy in the lower troposphere than in the upper troposphere, reducing tropospheric stability.

Regional climate projection over South Korea simulated by the HadGEM2-AO and WRF model chain under RCP emission scenarios

“…For example, the HadGEM-AO projection over our target region is not markedly different from that of the CMIP5 multi-model ensemble mean. The increases in temperature and precipitation around the Korean peninsula projected by HadGEM-AO (Baek et al 2013) are consistent with the CMIP5 multi-model ensemble mean reported in Qu et al (2014), Lee & Wang (2014), and Seo et al (2013). In addition, WRF-downscaled results are also in line with other projections using different RCMs driven by the HadGEM-AO (e.g.…”

“…Consistent with our result, several studies have supported the intensification of the East Asian summer monsoon under global warming based on CMIP5 projections (e.g. Chen & Sun 2013, Jiang & Tian 2013, Seo et al 2013, Lee & Wang 2014, Qu et al 2014, Tian et al 2015. As shown in Chapter 14 of the IPCC AR5 (Christensen et al 2013), CMIP5 projections indicate a likely increase in both the circulation and rainfall of the East Asian summer monsoon through the 21st century.…”

Drivers and mechanisms for enhanced summer monsoon precipitation over East Asia during the mid-Pliocene in the IPSL-CM5A

“…Here, to estimate the processes that are important for the EASM precipitation, the moisture budget equation is analyzed (Seo et al 2013). The vertically integrated moisture budget equation can be expressed as where q is specific humidity, V is three-dimensional wind, and 〈 〉 represents a vertical integration from 1000 to 100 hPa.…”

Future Change Using the CMIP5 MME and Best Models: II. The Thermodynamic and Dynamic Analysis on Near and Long-Term Future Climate Change over East Asia

“…하지만 대기 중의 수 증기량의 증가에 비해 강수의 증가량은 C.-C. 관계에 서 보다 적게 나타나는 것으로 추정되었다 (Held and Soden, 2006). 이는 강수의 증가가 그 지역에서 수증 기량의 증가뿐만이 아니라 대기 순환에 의한 수송에 도 영향을 받기 때문이다 (Zhou and Yu, 2005;Held and Soden, 2006;Yun et al, 2008;Seo et al, 2013;Lee et al, 2014a, b;Oh and Ha, 2014). (Lee and Wang, 2014).…”