Analyses of tropical cyclone characteristics and its relation to environmental conditions based on IPRC-regional climate model

Many studies have identified the variations of TC activities in the past few decades and made future projections on TC behaviors in some warming scenarios based on numerical models. However, there still exist quite high uncertainties in modeling TC activities. In this study, the high-resolution IPRC (International Pacific Research Center) regional climate model is used to simulate TC activities in the western North Pacific during July to October from 1982 to 2001. The NCEP reanalysis and NOAA Optimum Interpolation SST data are used as the boundary conditions to produce four ensemble members, starting from different initial dates (i.e. 28, 29, 30 June and 1 July, respectively, in each year). Detailed analyses of the relationship among the long-term statistics of TC behaviors, environmental conditions and large-scale circulations are performed. The results show that the difference of the TC number among these four members is significant in some years even though the boundary conditions of these members are the same. The potential mechanisms of the impact on TC activities from the model's interior dynamical processes and the dynamical constraints of the scale interaction between the large-scale circulations and TCs are under examination. It is hoped that these results could provide better insights into the understanding of TC characteristics in regional climate models.