Changes of Baiu (Mei-yu) Frontal Activity in the Global Warming Climate Simulated by a Non-hydrostatic Regional Model

The Baiu (Mei-yu) front over East Asia in the global warming climate as well as that in the present one, is studied using outputs of a non-hydrostatic regional model with a horizontal grid size of 5 km (NHM). The NHM was run in June and July for ten years, applying a spectral boundary coupling method to reduce the horizontal phase differences of large-scale disturbances using the outputs of a global climate model with a grid size of 20 km. In the global warming climate, the Baiu front is likely to stay over the southern Japan Islands around the latitudes of 30 N-32 N and will not move northward. Therefore, the activity of the Baiu front maintains longer than that in the present climate, and the precipitation increases. On the other hand, the precipitation decreases over the northern Japan Islands and the northern Korean Peninsula. Years with no end of the Baiu season are often seen, and the frequency of occurrence of heavy rainfall greater than 30 mm h(-1) increases over the Japan Islands.