Comparative analysis of the rainstorms caused by two typhoons in inland China

Typhoon Haikui and Matmo made landfall in China and passed through Anhui Province in August 2012 and July 2014, respectively. Both of them caused regional heavy rainstorm in Anhui Province. By using daily observational data, the NCEP/NCAR reanalysis data and raindrop size distributions observed at Chuzhou, the tracks and the mechanisms of the rainstorms caused by the two typhoons are analyzed and compared. The results are as follows:(1) Typhoon Haikui and Matmo were distinctly different in their moving paths. The lasting time and heavy rainfall distributions of the rainstorms caused by the two typhoons were also quite different. Compared with Haikui, Matmo was characterized by faster moving speed, shorter rainfall duration, smaller cumulative rainfall and rainstorm range. In addition, the heavy rainfall duration associated with Matmo was longer and the precipitation intensity of the rainstorm center was greater. (2) Although strong water vapor transport and convergence occurred during the precipitation process associated with both Haikui and Matmo, their spatial and temporal distributions were different. Due to different water vapor transports, the heavy rainfall distribution of Haikui exhibited a zonal pattern, while that of Matmo showed a meridional pattern. Furthermore, the duration of moisture convergence can explain why the Matmo's rainfall duration was shorter than that of Haikui. However, the deep moisture convergence of Matmo made the heavy rainfall last longer and enhanced the rainfall intensity at the rainstorm center. (3) The precipitation of Haikui was a mixed type with the majority being stratiform precipitation, while the precipitation of Matmo was characterized by convective precipitation. During both of the two typhoon precipitation processes, short-period convective precipitation made large contribution to the total rainfall, and heavy rainfall mostly occurred on the left side of the area where environmental vertical wind shear occurred. (4) Matmo had higher raindrop concentration and larger raindrop size than Haikui. When the rainfall intensity is less than 10 mm/h, a large number of small raindrops contributed to the precipitation in both typhoons. On the contrary, when rainfall intensity is higher than 10 mm/h, the raindrop size increased while the number decreased. (5) The two typhoon precipitation processes showed a good exponential relationship between Z and R, which is consistent with their fitting curves. However, for different precipitation types of stratiform and convective precipitation, the values of a and b are obviously different in the Z-R relationship. Therefore, for different types of precipitation, different Z-R relationships should be used to estimate precipitation based on radar observations.