Responses of summer mesoscale convective systems to irrigation over the North China Plain based on convection-permitting model simulations

Journal Article · 20 September 2024 · Environmental Research Communications

DOI: https://doi.org/10.1088/2515-7620/ad78ba · OSTI ID:2447691

Wang, Yixiao  ^[1]; Yang, Ben  ^[1]; Yang, Zhao  ^[2]; Feng, Zhe  ^[2]; Qiu, Bo  ^[1]; Dai, Guoqing ^[1]; Qian, Yun  ^[2]; Zhang, Yaocun ^[1]

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1. Nanjing Univ. (China)
2. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Extensive irrigation activities in the North China Plain (NCP) significantly influence regional weather and climate. However, previous studies focusing on the NCP were primarily based on coarse-resolution models, which are unable to explicitly resolve convection systems, causing large uncertainty in precipitation simulations. In this study, a convection-permitting model coupled with a dynamic irrigation scheme is utilized to investigate the impacts of irrigation on summertime mesoscale convective systems (MCSs) over the NCP. Sensitivity experiments with irrigation off and on are conducted for 5 summers and an MCS identification and tracking algorithm is applied to both satellite observations and model simulations. We find that incorporating irrigation in the model increases MCS precipitation, which agrees more with observations. The probability distributions of MCS lifetime, area, propagation speed, and intensity are all better simulated with irrigation. Irrigation increases the occurrence frequency of MCSs throughout the entire day. The nighttime increase is partly because of more frequent local initiation of MCS developed from isolated deep convection, while the daytime increase is mainly attributed to the changes in MCSs initiating elsewhere and then propagating to the NCP. On average, irrigation induces additional moisture that is more thermodynamically favorable for precipitation, but this effect is partially offset by the weakened ascending air motion primarily caused by irrigation surface cooling. Compared to weak MCS precipitation events, strong MCS precipitation events experience greater enhancement in precipitation intensity when including irrigation because the offset effect from the change in large-scale ascending air motion is insignificant. In addition, irrigation makes the variation of MCS precipitation intensity more correlated with the variation in ascending motion but less correlated with that in atmospheric moisture. Our results suggest the pronounced impacts of irrigation on MCSs over the NCP which should be included in numerical models to improve regional precipitation simulation and prediction.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); National Natural Science Foundation of China (NSFC); Fundamental Research Funds for the Central Universities
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 2447691
• Report Number(s): PNNL-SA--200847
• Journal Information: Environmental Research Communications, Journal Name: Environmental Research Communications Journal Issue: 9 Vol. 6; ISSN 2515-7620
• Publisher: IOP ScienceCopyright Statement
• Country of Publication: United States
• Language: English