| 摘 要： |
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 degrees 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. Mesoscale convective systems (MCSs) play a crucial role in generating heavy rainfall during severe rainfall events, such as the record-breaking rainfall occurred in Henan Province, China, in July 2021. Here, we investigate whether the MCSs during this extreme event are intensified due to global warming. We use a numerical model to simulate the MCSs under two different scenarios-the current climate background and a 0.8 degrees C colder climate, which analog to the pre-industrial climate. Our results indicate that the total rainfall from MCSs increased by 10.0% due to global warming, with a 3.1% larger MCSs area and a 6.7% stronger hourly rainfall intensity. Global warming also leads to a faster development of MCSs by providing favorable warmer and wetter atmosphere. When the MCSs are mature, the maximum hourly rainfall intensity can increase by up to 26.5% per degrees C. The center of MCSs could remain unmoved or shift, depending on the interaction between low-level flow and terrain. This study illustrates that MCSs can produce much stronger rainfall under global warming with varying changes during the developing and mature phases. These results provide deeper insight into the impacts of global warming to extreme rainfall events. Global warming intensifies the mesoscale convective system (MCS) during the record-breaking extreme rainfall event in July 2021 in Henan, China Global warming leads to a faster growth of MCS during its developing stage The interaction between terrains and moist flow may lead to different responses of rainfall centers to warming |
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