WRF Dynamical Downscaling for High-Intensity Typhoons of D4PDF

Global climate models have a relatively coarse spatial resolution that may not capture the fine-scale features and local atmospheric processes associated with tropical cyclones (TCs). Hence, there is a high demand for regional dynamical downscaling models with higher resolution that can refine the spatial details and provide a more accurate representation of TC characteristics and their interactions with the local environment. The Database for Policy Decision Making for Future Climate Change (d4PDF) is an unprecedentedly large ensemble dataset that enables the assessment of past and future extreme events including TCs. It comprises results from both a global atmospheric General Circulation Model (GCM) and a Regional Climate Model (RCM). In previous studies, the primary focus of regional-scale applications of the d4PDF dataset has been to assess the impacts of climate change on temperature and precipitation. Nevertheless, the impact of the downscaling process from GCM to RCM on the center pressure of high-intensity typhoons remains unexplored. In this study, we employed the d4PDF dataset to analyze typhoons, which are TCs that occur in the northwestern Pacific Ocean. We have examined that the results from RCM indicate a weakening of the center pressure of high-intensity typhoons, in contrast to the results obtained from the GCM. Hence, this study attempts to utilize initial and boundary conditions from GCM instead of RCM to drive WRF dynamical downscaling. The WRF downscaling demonstrated stronger agreement with the GCM, highlighting the reliability of this approach for downscaling high-intensity typhoons in the d4PDF dataset.