Comparison of Synoptic Circulation Characteristics in Different Types of Warm-Sector Heavy Rainfall Events over South China

Based on the objective classification of warm-sector heavy rainfall events over South China, a synoptic analysis is used to study the similarities and differences between the circulation characteristics and environmental variables for the different types of warm-sector rainfall events. Results reveal that most of the shear line type, vortex type, and backflow type warm-sector rainfall events have strong baroclinic environments, with the backflow type being the strongest and the south wind type being relatively weak. All warm-sector rainfall events are controlled by the horizontal westerly airflow at the middle latitudinal area when they occurred. The precipitation area is mainly located in front of the short-wave trough and is affected by the low-level jet at lower layers. The main differences between the different types of warm-sector rainfall events are the location and intensity of the South Asia high, middle-level wave trough, western Pacific subtropical high, and low-level jet, and the difference between the wind direction and water vapor condition. Different types of warm-sector rainfall events exhibit differences between the environmental variables. The shear line warm-sector rainfall has the strongest vertical wind shear (0–3 km) in five types, and the vortex type has the largest convection effective potential energy. The dynamic and thermal forces of the two types of southerly warm-sector rainfall events are the weakest among all types of warm-sector rainfall events. The mechanism of its occurrence and development needs to be further studied.