Assessments on climatologic simulation of atmospheric dynamic environment of tropical cyclone over western North Pacific in IPCC-AR4 models

The fidelity of atmospheric circulation over tropical regions, especially subtropical high, monsoon trough and vertical wind shear over the regions of tropical cyclone activity in the coupled general circulation models (CGCM) participating in the Forth Assessment Report (AR4) of Intergovernmental Panel on Climate Change (IPCC)is accessed by virtue of comparing simulated climate field with that of National Center Environmental Prediction(NCEP)/National Center Atmospheric Research(NCAR) during 1948—1999 from July to September. It is found that vast majority of 23 IPCC-AR4 models show a good performance in mean state in 500 hPa height field over the domain 0°—40°N, 0°E—180°—0°W and 850 hPa wind field over the region 20°S—40°N, 0°E—180°—0°W—180°—0°W, but in comparison to that of NCEP/NCAR, most of models show a low bias in 500 hPa height and a strong bias in 850 hPa wind flow.The subtropical high ridge over the western North Pacific of all models is in NE-SW orientation which is similar to that of NCEP/NCAR, but some of models' ridge locates to far away from the latter. Monsoon troughs of four models are absent from 850 hPa flow and six of monsoon troughs in models occur to the west of 140°E. According to the performance of simulation in spatial structure of atmospheric circulation over tropical area, subtropical high ridge, monsoon trough in the western North Pacific and vertical wind shear in active regions of tropical cyclone over western North Pacific in summer(from July to September), the first ten excellent models are successively mpi_echam5、cccma_t63、gfdl_cm2_1、cnrm_cm3、cccma_t47、ukmo_hadgem1、ingv_echam4、ncar_ccsm3_0、csiro_mk3_5、mri_cgcm2_3_2a and the last six models are successively inmcm3_0、iap_fgoals1_0_g、ipsl_cm4、miroc3_2_medres、giss_eh、giss_er.