Future Thermodynamic Impacts of Global Warming on Landfalling Typhoons and Their Induced Storm Surges to the Pearl River Delta Region as Inferred from High-Resolution Regional Models

Possible thermodynamic effects of global warming on the landfalling typhoons that affect South China and their associated storm surges over Pearl River Delta region are investigated, using the Weather Research and Forecasting (WRF) Model and the Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model based on the pseudo-global warming (PGW) technique. Twenty intense historical TCs that brought extreme storm surges to Hong Kong since the 1960s are selected and replicated by the 3-km WRF Model, with the outputs to drive the SLOSH model in storm surge simulation. The tracks, intensities, storm structure, and induced storm surges are well simulated. The PGW technique is then used to build a warmer background climate for the 20 selected TCs in the period of 2075-99 under the RCP8.5 scenario. To obtain a better adjusted warming environment, a pre-PGW adjustment method is developed. Comparing the same TCs in PGW experiments and historical runs, the TC lifetime peak (landfall) intensity can be intensified by about 9% +/- 8% (12% +/- 13%), with a similar to 3% increase of TC peak intensity per degree of SST warming being inferred. The TCs are projected to be more compact, with the radius of maximum wind (RMW) reduced by similar to 7% +/- 10%. TC precipitation is also expected to increase, with the extreme precipitation within the eyewall strengthened by 22% +/- 12%. All the above characters have passed the Student's t test at 0.05 significance level. Finally, the projected induced storm surges near the Hong Kong waters are not significantly tested, although a weak storm surge height increase tendency is revealed.