Responses of Mesoscale Convective System to Global Warming: A Study on the Henan 2021 Record‐Breaking Rainfall Event

Abstract

The limited capabilities of global climate models in simulating mesoscale convective systems (MCSs) restrict our understanding of how global warming impacts MCSs. This study uses a high‐resolution numerical model with large‐ensemble experiments to simulate MCSs during the record‐breaking extreme rainfall event in Henan Province, China, in July 2021. We compare the changes in the MCS's strength, size, and structure in a real‐world simulation (RW) and a 0.8°C colder simulation (analog to no‐anthropogenic‐warming‐world simulation, short for NAWW) to assess the response of MCSs to global warming. Our results show that the total rainfall from the MCS increased by 10.0% in RW compared to NAWW, with a 3.1% increase in area and a 6.7% increase in rainfall intensity. The development of MCS becomes more rapid in response to warming since the pre‐industrial era. The warmer and wetter climate results in higher convective available potential energy, and accelerates the MCS growth, but then the narrower low‐convective inhibition regions suppress the continuous growth of MCS. During the mature phase, the maximum hourly rainfall intensity (Pmax) can increase by up to 26.5%/K, while Pmax locations can either remain unchanged or shift depending on the interaction of flows and terrains. These results highlight varying responses of MCSs to global warming during its different stages and provide valuable insights into the changing characteristics of extreme rainfall events under global warming.