Evaluation And Projection Of Interannual Variability Of The East Asian Winter Monsoon In CMIP5 Models

The Climatology, interannual variability of the East Asian winter monsoon and the impact of the simulation ability of the relationship between El Nino and EAWM(El Nino-EAWM) in models on the EAWM is evaluated in 17 CMIP5 models by using the statistical methods and selecting the elements including sea level temperature(SLP), surface air temperature(SAT),850hPa wind field(850U,850V), 500hPa geopotential height(Z500) and 200hPa zonal wind(U200). On the basis of assessment, the climate in the next 50 years is projecting under the medium greenhouse gas emissions scenario(RCP4.5). The results show that:(1)MME can well capture the characteristics of the circulation in East Asia; The climatology of the East Asia can be captured by all of the models, which have best simulation capability for U200 and SAT in space, for Z500 in strength. Models have best simulation capacities in surface temperature and 500hPa geopotential height integrated both of spatial and intensity. In addition, the Tibetan Plateau plays an important impact on the lower elements in models(2)Most models have ability to simulate the interannual variability of EAWM, the interannual variability of main systems is simulated better in space than in intensity, and most models simulate slightly weaker than the observations in intensity. But deviation is relatively large between models, wherein the interannual variability of East Asian trough analog best. Through a comprehensive assessment found that bcc-csm1-1, CCSM4, HadCM3and NorESM1-M have good simulation capability in EAWM, GISS-E2-R, inmcm4, MIROC5, MPI-ESM-LR and MRI-CGCM3 have bad.(3) According to the large deviation of the interannual simulation ability among models, two types of models which have best and worst simulation variability are then discussed. The simulation ability of the El Nino-EAWM of models is one of the most important factors for the bias by evaluating the influence of El Nino on the circulation in East Asia winter. In other words, the success of these models’good interannual simulation ability is attributed to the reasonable simulation of El Nino-EAWM.(4)In the future, the Aleutian Low will be weaker, while the Siberian High will be weak in the north part and strong in the south part which is influenced by the Tibet Plateau; The East Asian trough will not change significantly and the westerly jet stream will slightly increased. The temperature in the East Asia will be rising with the greenhouse gas continuing increase, the average heating rate is 0.343℃/10a, which is three times over the past global average surface temperature. The East Asian trough gradually weakened indicating that EAWM will be slightly weakening in the future.