East Asian Summer monsoon (EASM) has prominent impacts on the local climate of East Asia because it increases the frequency of deep convections and precipitation. Due to the limitations in orography and resolutions etc., the general circulation models usually have bias in simulating EASM. The local cloud, as a component of EASM, is traditionally regarded as a result of atmospheric circulation changes associated with the EASM system. However, besides the well-known latent heat releasing, the radiative effects of clouds may also have effect on the EASM circulation by changing the profile of heating rates.
Recently, Dr. GUO Zhun and Dr. ZHOU Tianjun (Institute of Atmospheric Physics), Prof. WANG Minghuai (Nanjing University), and Dr. Yun QIAN (Pacific Northwest National Laboratory, USA) tried to investigate the effects of cloud on the simulation of EASM by blocking cloud radiations over Southeastern China in a general circulation model. Their sensitive experiments show that the EASM circulation and precipitation would be much weaker than that in the normal condition, when the cloud radiations are ignored. Clarifying the importance of cloud radiative heating cannot only provide a useful understanding of EASM but also a possible way to reduce the bias in the simulation of EASM.
The horizontal distributions of Precipitation (shading, units: mm/day) and 850 hPa winds (vectors, units: m/s) in JJA during 1979-2011. (a) Observations, (b) control run, (c) differences between no-longwave run and control run, (d) and (e) are same with (c), but for no-shortwave and no-net radiations runs separately. The dotted areas indicate that the precipitation anomalies are statistically significant at the 10% level. The masked areas mean that the topography is higher than 1.5 km. The red boxes are southeastern China (105°-125°E, 20°-35°N). (Guo et al, 2015)
Their study is published in Environmental Research Letters (doi:10.1088/1748-9326/10/7/074014).
Reference: Guo, Z., T. Zhou, M. Wang, Y. Qian: Impact of cloud radiative heating on East Asian summer monsoon circulation. Environmental Research Letters, 10(7), 074014, doi:10.1088/1748-9326/10/7/074014, 2015.
Contact: Dr. GUO Zhun, guozhun@lasg.iap.ac.cn
