scholarly journals Disentangling fast and slow responses of the East Asian summer monsoon to reflecting and absorbing aerosol forcings

2017 ◽  
Author(s):  
Zhili Wang ◽  
Lei Lin ◽  
Meilin Yang ◽  
Yangyang Xu ◽  
Jiangnan Li
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Sea Surface ◽  
Slow Response ◽  
Total Response ◽  
Thermal Contrast ◽  
Response Component ◽  
Asian Summer

Abstract. We examine the roles of fast and slow responses in shaping the total equilibrium response of the East Asian summer monsoon (EASM) to reflecting (sulfate, SO4) and absorbing (black carbon, BC) aerosol forcings over the industrial era using the Community Earth System Model version 1. Our results show that there is a clear distinction between fast and slow responses of the EASM to aerosol forcings and the slow climate response due to aerosol-induced change in sea surface temperature plays an important role in the impacts of aerosols on the EASM. The EASM is weakened by a decrease in land-sea surface thermal contrast in the fast response component to SO4 forcing, whereas the weakening is more intensive by the changes in tropospheric thermodynamic and dynamic structures in the slow response component to SO4. The total climate adjustment caused by SO4 is a significant weakening of the EASM and a decrease in precipitation. The BC-induced fast adjustment strengthens the EASM both by increasing the local surface land-sea thermal contrast and shifting the East Asian subtropical jet northwards. BC-induced slow climate adjustment, however, weakens the EASM through altering the atmospheric temperature and circulation. Consequently, the EASM is enhanced north of 30° N but slightly reduced south of 30° N in the total response to BC. The spatial patterns of precipitation change over East Asia due to BC are similar in total response and slow response. This study highlights the importance of ocean response to aerosol forcings in driving the changes of the EASM.

scholarly journals Disentangling fast and slow responses of the East Asian summer monsoon to reflecting and absorbing aerosol forcings

2017 ◽  
Vol 17 (18) ◽  
pp. 11075-11088 ◽  
Author(s):  
Zhili Wang ◽  
Lei Lin ◽  
Meilin Yang ◽  
Yangyang Xu ◽  
Jiangnan Li
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Atmospheric Temperature ◽  
Sea Surface ◽  
Slow Response ◽  
Total Response ◽  
Thermal Contrast ◽  
Asian Summer

Abstract. We examine the roles of fast and slow responses in shaping the total equilibrium response of the East Asian summer monsoon (EASM) to reflecting (sulfate, SO4) and absorbing (black carbon, BC) aerosol forcings over the industrial era using the Community Earth System Model version 1 (CESM1). Our results show that there is a clear distinction between fast and slow responses of the EASM to aerosol forcings and the slow climate response due to aerosol-induced change in sea surface temperature (SST) plays an important role in the impacts of aerosols on the EASM. The EASM is weakened by a decrease in land–sea surface thermal contrast in the fast response (FR) component to SO4 forcing, whereas the weakening is more intensive due to the changes in tropospheric thermodynamic and dynamic structures in the slow response (SR) component to SO4. The total climate adjustment caused by SO4 is a significant weakening of the EASM and a decrease in precipitation. The BC-induced fast adjustment strengthens the EASM both by increasing the local land–sea surface thermal contrast and shifting the East Asian subtropical jet (EASJ) northwards. The BC-induced slow climate adjustment, however, weakens the EASM through altering the atmospheric temperature and circulation. Consequently, the EASM is slightly enhanced, especially north of 30° N, in the total response (TR) to BC. The spatial patterns of precipitation change over East Asia due to BC are similar in the total response and slow response. This study highlights the importance of ocean response to aerosol forcings in driving the changes of the EASM.

Relationship between sea surface temperature anomalies over tropical Atlantic in late spring and East Asian summer monsoon

2020 ◽  
Author(s):  
Joong-Bae Ahn ◽  
Yeon-Woo Choi
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Late Spring ◽  
Sea Surface ◽  
Tropical Atlantic ◽  
Asian Summer

<p>This study investigates the relationship between the preceding late spring Sea Surface Temperature (SST) over the tropical Atlantic and the East Asian Summer Monsoon (EASM) based on the observational data and Coupled Model Intercomparison Project Phase 5 (CMIP5) historical simulations. The results show that warm (cold) tropical Atlantic SST (TASST) during May tends to be followed by a strong (weak) EASM with positive (negative) precipitation anomalies over the subtropical frontal area. Evidence is also provided that the atmospheric teleconnections propagating in both east and west directions are the key mechanisms linking the EASM with the preceding May TASST. That is, the warm TASST anomaly during late spring can persist through the subsequent summer, which, in turn, induces the Gill-type Rossby wave response in the eastern Pacific, exciting the westward relay of the Atlantic signal, as well as the eastward propagation of the Rossby wave along the jet stream. Furthermore, the westward (eastward) propagating teleconnection signal may induce the anomalous anticyclone in the lower troposphere over the Philippine Sea (anomalous tropospheric anticyclone with barotropic structure over the Okhotsk Sea). The anomalous anticyclonic circulation over the Philippine Sea (Okhotsk Sea) brings warm and humid (cold) air to higher latitudes (lower latitudes). These two different types of air mass merge over the Baiu-Meiyu–Changma region, causing the enhanced subtropical frontal rainfall. To support the observational findings, CMIP5 historical simulations are also utilized. Most state-of-the-art CMIP5 models can simulate this relationship between May TASST and the EASM.</p><p>Reference: Choi, Y., Ahn, J. Possible mechanisms for the coupling between late spring sea surface temperature anomalies over tropical Atlantic and East Asian summer monsoon. Clim Dyn <strong>53, </strong>6995–7009 (2019) doi:10.1007/s00382-019-04970-3</p><p>Acknowledgment: This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI2018-01213.</p><p> </p>

scholarly journals Weakening Relationship between East Asian Summer Monsoon and Asian-Pacific Oscillation after 1990s

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Wei Hua ◽  
Zouxin Lin ◽  
Xin Wang ◽  
Guangzhou Fan
Keyword(s):  
Summer Monsoon ◽  
North Pacific ◽  
East Asian Summer Monsoon ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Thermal Contrast ◽  
The Pacific ◽  
Asian Summer ◽  
Asian Pacific

The East Asian summer monsoon (EASM), which is an important influencing summer climate of East Asia, is associated with large-scale change of the land-sea thermal contrast. The Asian-Pacific Oscillation (APO) can modulate the EASM because it not only represents the upper-tropospheric zonal land-sea thermal contrast over Asia and the Pacific region, but it also affects the sea surface temperature (SST) over the North Pacific, which can tune the land-sea thermal contrast for the EASM. This study revealed weakening of the APO-EASM relationship since the 1990s. It was found that the relationship between the APO and the EASM during 1948–1990 (1991–2016) was statistically significant (insignificant). Further study indicated that the APO was concurrent with significant positive SST in the central North Pacific and subtropical central-western Pacific during 1948–1990, which contributed to the shift of the Pacific Decadal Oscillation (PDO) from its cold to warm phase and led to a weakened EASM. The APO-related SST and atmospheric circulation anomalies were found statistically to be insignificant during 1991–2016, which indicates a weakening of influence of the APO on shift of the PDO, and even a weaker link to the EASM.

scholarly journals Early Summer Response of the East Asian Summer Monsoon to Atmospheric CO2 Forcing and Subsequent Sea Surface Warming

2016 ◽  
Vol 29 (15) ◽  
pp. 5431-5446 ◽  
Author(s):  
Jinqiang Chen ◽  
Simona Bordoni
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Summer Rainfall ◽  
Early Summer ◽  
Sea Surface ◽  
Atmospheric Co2 ◽  
Asian Summer ◽  
Co2 Forcing

Abstract The early summer regional climate change of the East Asian summer monsoon (EASM) is investigated in the phase 5 of the Coupled Model Intercomparison Project (CMIP5) archive. In the greenhouse gas–forced scenario, reduction of radiative cooling and increase in continental surface temperature occur much more rapidly than changes in sea surface temperatures (SSTs). Without changes in SSTs, the early summer rainfall in the monsoon region decreases (increases) over ocean (land) in most models. On longer time scales, as SSTs increase, rainfall changes are opposite. The total response to atmospheric CO2 forcing and subsequent SST warming is a large (modest) increase in rainfall over ocean (land) in the EASM region. Dynamic changes, in spite of significant contributions from the thermodynamic component, play an important role in setting up the spatial pattern of precipitation changes. Early summer rainfall anomalies over east China are a direct consequence of local land–sea contrast, while changes in the large-scale oceanic rainfall band are closely associated with the displacement of the larger-scale North Pacific subtropical high (NPSH). Ad hoc numerical simulations with the AM2.1 general circulation model show that topography and SST patterns play an important role in early summer rainfall changes in the EASM region.

Sign in / Sign up

Export Citation Format

Share Document