Synoptic classification and statistical characteristics of physical diagnoses for thunderstorm gale in Shandong Province

In this study, we divide the region covering Shandong Province into inland and peninsula area. By using the surface meteorological observation and sounding data from the MICAPS, we have conducted a classification to the thunderstorm gale events occurred between April and September from 2009 to 2016 in Shandong Province primarily based on the 500 hPa synoptic systems. In addition, based on the mesoscale weather systems in the 850 hPa and at the surface, the different patterns of thunderstorm gale events are classified. Then the physical diagnose of each pattern of thunderstorm gale event is statistically analyzed by using the percentile method, and the critical values of these physical diagnoses are given. The results show that (1) based on the configuration of the 500 hPa weather influence systems, the thunderstorm gales in Shandong can be divided into pre-trough pattern, post-trough pattern and around subtropical high pattern. Additionally, according to the relation between the falling area of thunderstorm strong wind and the 850 hPa weather systems, they can also be divided into three types, i.e. shear line convergence, southerly airflow convergence and northerly airflow convergence. Furthermore, according to the position relationship between the weather system and the thunderstorm gale in the sea-level pressure field, the surface weather systems that generate thunderstorms high winds can be mainly divided six types. (2) The suitable physical diagnoses of thunderstorm gales between April and June in the inland area of Shandong are temperature difference (ΔT_850-500) between 850 hPa and 500 hPa, velocity difference (ΔV_500-850) between 500 hPa and 850 hPa, Storm Strength Index (SSI) and Wind Index (WI), while in the peninsula area of Shandong, the physical diagnoses SSI and WI, which can represent the comprehensive characteristics of atmospheric thermodynamics and dynamics, show a good indication to thunderstorm gales in this area. (3) The physical diagnoses Convective Available Potential Energy (CAPE), K index, Lift Index (LI), pseudo-equivalent potential temperature difference (Δθ_se700-850) between 700 hPa and 850 hPa and severe weather threat index (SWEAT), representing atmospheric thermal instability, have good indicative signification to the thunderstorm gales between July and August in Shandong province. (4) Δθ_se700-850, SSI, SWEAT and ΔV_500-850 have good indication to the thunderstorm gales occurred in the peninsula area of Shandong in September.