An Evaluation Of Latent Heat Flux Over The Sea Surface Affecting The South China Summer Simulated In BCC_CSM1.1m

In this paper, the standardized precipitation evapotranspiration index、OAFlux data sets and 15 CMIP5 models simulations are used to find the key sea areas of latent heat flux which impact summer drought of the south China and investigate the variations of latent heat flux over these key areas and the possible influence physical mechanisms. The model performance related to climatology and trend of latent heat flux over these key areas are then evaluated by BCC_CSM1.1m climate model. The main results are summaried as below.(1) There exists an obvious interdecadal change from dry to wet in the southern China in the early 1990s, as well as latent heat flux in the tropical Pacific and North Atlantic Oceans from weak to strong. The summer latent heat flux anomaly in the key area of the North Atlantic may affects the summer drought in the southern China through the atmospheric teleconnetion wave at the upper troposphere. There are indirect and direct ways which the summer latent heat flux anomaly in the the tropical western Pacific impact the the summer drought in the south China. The indirect way is that the anomaly over this key area firstly impacts Walker circulation and then the South Asia High, resulting in the drought in the southern China. The direct way of the anomaly over this key area affecting the drought in the southern China is through the local meridional circulation cell.(2) Among the 15 CMIP5 models’abilities in simulating the summer latent heat flux in the two key areas, i.e., the tropical western Pacific and north Atlantic Oceans, BCCCSM1.1m ranks eighth and third respecitively.(3) The possible main reasons of BCCCSM1.1m deviations on the Climatology and trend of summer latent heat flux in the tropical western Pacific compared to the observation are investigated by the perturbation decomposition method. ①BCC_CSM1.1m underestimates the local effect of the wind speed on the trend of latent heat flux, Afte rthe disturbance decomposition of BCC_CSM1.1m simulation, the spatial structures of sea surface temperature and specific humidity items exhibt the uniform structures, which are inconsistent with the observation, resulting in BCC_CSM1.1m failing on simulating non-local contributions of the wind speed to the trend of latent heat flux; ②BCC_CSM1.1m overestimates the positive contribution of the SST on the trend of latent heat flux;③BCC_CSM1.1m fails to simulate the response of the wind speed to global warming.