Effects of Typhoon In‐Fa (2021) and the Western Pacific Subtropical High on an Extreme Heavy Rainfall Event in Central China.

An extreme heavy rainfall event in Henan Province (HnHRE) of central China in July 2021, which is jointly affected by the western Pacific subtropical high (WPSH) and Typhoon In‐Fa (2021), is comprehensively studied through five experiments conducted using the Weather Research and Forecasting Model (WRF). The patterns of the WPSH, In‐Fa, and precipitation are well reproduced in the control experiment. The magnitude of potential vorticity (PV) anomaly associated with the WPSH (In‐Fa) is increased and decreased by 50% in the initial condition based on the piecewise PV inversion method, namely, SH150 and SH050 (TC150 and TC050), respectively. The analysis shows that the 54‐hr rainfall accumulations in TC150 and TC050 are reduced by 39.5% and 31.8%, respectively, more than 28.8% in SH150 and 20.1% in SH050, indicating that Typhoon In‐Fa plays a more critical role in the rainfall amplification than the WPSH. This result also confirms that the HnHRE occurs within the quite favorable configuration of WPSH and In‐Fa circulations. The WPSH and In‐Fa majorly control the meridional and zonal moisture transports, respectively. The diagnosis of moist ageostrophic ω $\omega $ turns out that diabatic heating is closely related to the vertical motion during the HnHRE. Besides, the heavy rainfall region is also closely attributed to the distributions of equivalent potential temperature and divergence. Plain Language Summary: This study focuses on a typical heavy rainfall event (HRE) related to the western Pacific subtropical high (WPSH) and Typhoon In‐Fa (2021). The study aims to quantitatively analyze the effects of the WPSH and In‐Fa and their interactions, which play a vital role in the HRE. The distribution and amount of rainfall are reasonably reproduced in a numerical model. Moreover, the four sensitivity experiments are conducted to identify the influence of the WPSH and In‐fa on the HRE. The results confirm that the HRE occurs under the highly favorable WPSH and In‐Fa circulations and their cooperation. Typhoon In‐Fa plays a more critical role in rainfall amplification than the WPSH. This finding emphasizes that the interaction of the WPSH and typhoon has an important effect on the HRE. Key Points: Typhoon In‐Fa plays a more critical role in the rainfall amplification than the western Pacific subtropical highThe western Pacific subtropical high and Typhoon In‐Fa majorly control the meridional and zonal moisture transports, respectivelyDiabatic heating plays a primary role in vertical motion during this heavy rainfall event [ABSTRACT FROM AUTHOR]