The relationship between climatic changes and convective conditions of heavy rain in Fuyang of Anhui Province from 1962 to 2016

Climatic characteristics and convective conditions of heavy rain were analyzed based on the daily rainfall data at 6 observation stations in Fuyang and the NCEP/NCAR reanalysis data from 1962 to 2016. The results show that the heavy rain increased obviously in recent 55 years, and changed abruptly in 1989, which was also a major contributor to the increase in annual rainfall. Heavy rain occurred mainly from May to September, especially in June and July. The heavier the rain occurs in summer, the higher the heavy rain concentration index can be found. Three convective parameters including K index, precipitable water and vertical velocity at 850 hPa have been chosen based on the convection stability, wanted vapor condition and lifting condition. The threshold statistical method has been used to analyze the climatic trend and convective conditions. Compared to the climatic mean statistics, the threshold statistical method had obvious advantages in interdecadal and interannual timescale, or for abnormal years of heavy rain analysis. The threshold statistics showed that interdecadal and interannual variability of heavy rain had a good relationship with K index, precipitable water and vertical speed on 850 hPa that provide the favorable convective conditions for the heavy rain formation. However, the impacts of convective conditions on the trend of rainstorm were different from May to September during the recent 55 years.