Identification and characteristics analysis of Meiyu in Anhui Province based on the National Standard of Meiyu monitoring indices

Meiyu is the term used to depict the consecutive rainy weather advancing in the months before the flooding season in East Asia. However, the temporal-spatial climatic characteristics of Meiyu can be differently specified by different evaluation criteria. In this study, we employ both the atmospheric circulation conditions and meteorological factors to identify the spatial characteristics of precipitation of Meiyu in Anhui Province using the collected data of 1957-2020. We further conduct a comparison analysis of the precipitation characteristics in the northern Huaihe River of Aihui province (NHA) with Meiyu rainfall features in two other regions: south of the Yangtze River in Anhui Province (SYA) and the region between the Yangtze River and Huaihe River in Anhui Province (YHA). Finally, the relation between the intensity index between Meiyu and flood or drought is investigated. The results showed that the climatic feature in NHA is a transitional region between Meiyu and non-Meiyu. Also, we proposed a Meiyu intensity index determined by the precipitation amount, intensity, and days of heavy rain. This index performs better than the Meiyu intensity index of National Standard in terms of flood and drought identification.