A global high-resolution coupled general circulation model (CGCM) consisting of a T319 atmosphere general circulation model and an eddy-permitted ocean general circulation model is examined in terms of the reproducibility of the northern hemisphere tropical cyclone (TC) activity as well as the large-scale environmental conditions. The CGCM successfully simulates the realistic TC structure, TC-induced ocean response, and TC genesis frequency. The global TC genesis frequency simulated by the high-resolution CGCM is much closer to the observed, compared that simulated by the medium-resolution (T106) CGCM. In addition, the high-resolution CGCM partially reproduces the bimodal seasonal cycle of the North Indian Ocean cyclogenesis, while the medium-resolution CGCM fails to simulate it. The high-resolution CGCM also reasonably reproduces the environmental conditions favorable for the TC genesis: warm sea surface temperature, low-level cyclonic circulation, weak vertical wind shear, and high relative humidity in the mid-troposphere. The eastward extension of monsoon-trough is well simulated by the high-resolution CGCM as observed, compared to the medium-resolution CGCM. There are, however, still some discrepancies between the modeled and observed TC activity. We discuss about the following two discrepancies from the view point of the simulated large-scale environmental conditions: the high-resolution CGCM fails to reproduce the bimodal seasonal cycle of the Arabian cyclogenesis during the pre-monsoon period, and the western North Pacific TC genesis locations are confined in the southwestern part of the western North Pacific. It is found that less Arabian cyclogenesis during the pre-monsoon period is due to the weak low-level cyclonic circulation in the Arabian Sea during this period, although the weak vertical wind shear is well simulated as observed. For the western North Pacific, less TC genesis in the southeastern part of the western North Pacific is found to be due to the failure to simulate the eastward extension of the monsoon-trough up to the international dateline. Compared to a medium-resolution CGCM, one of the advantages of the high-resolution CGCM is the reproduction of the intense TC. Surface wind speed exceeding 20~40 ms-1 is successfully simulated by the high-resolution CGCM, while the TC wind speed simulated by the medium-resolution CGCM is less than 20~30 ms-1. The frequency distribution of TC surface wind speed simulated by the high-resolution CGCM is closer to the observed compared to the medium-resolution CGCM.Edited by K. Oouchi and H. Fudeyas
