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<p>Persistent low-temperature, rain-snow, and freezing (LTRSF) weather is a catastrophic extreme event resulting from interaction between weather systems from different latitudes across various spatial–temporal scales. However, distinct discrepancies in weather and climate regimes among LTRSF events remain poorly understood. In this study, we conduct a comparative analysis of the extreme LTRSF events of 2008 and 2022 in South China. The 2008 LTRSF was characterized by persistent freezing, while the 2022 LTRSF featured more frequent rain-snow occurrences. Both extreme LTRSF events exhibit the typical circulation pattern of a blocking high coupled with a westward-shifted East Asia trough. However, significant differences in the intensity of cold air and moisture transport between the two events were observed. These differences were attributed to discrepancies in the India-Burma trough (IBT) and mid-high latitude trough-ridge patterns, which were influenced by Rossby wave activity flux propagation over Eurasia. Furthermore, our results indicate that the joint influence of La Niña and the positive North Atlantic Oscillation favored the occurrence of both events. The frequent rain-snow in 2022 event could be attributed to the synergistic effects of high sea ice anomalies in the northeastern East Siberian Sea-northern Chukchi Sea and La Niña. This combination could result in the deepened IBT and an anomalous anticyclone over the northwest Pacific, leading to increased precipitation. But remarkably, the Arctic sea ice anomalies alone play a negligible impact on LTRSF. These results can enhance our comprehension of LTRSF occurrence in South China and identify potential climate predictors for forecasting extreme LTRSF.</p>

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Synoptic regimes and climatic drivers of persistent low temperature, rain-snow, and freezing extremes over South China: a comparative analysis of 2008 and 2022

  • 期刊论文

  • 发表日期：

    2025年10月13日

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  • Runzhao Hu,
  • Yong Liu,
  • Huopo Chen,
  • Zhuozhuo Lyu,
  • Xiangyu Li,
  • Xiaorui Niu,
  • Hua Li,
  • Huixin Li,
  • Zhongshi Zhang

摘要

Persistent low-temperature, rain-snow, and freezing (LTRSF) weather is a catastrophic extreme event resulting from interaction between weather systems from different latitudes across various spatial–temporal scales. However, distinct discrepancies in weather and climate regimes among LTRSF events remain poorly understood. In this study, we conduct a comparative analysis of the extreme LTRSF events of 2008 and 2022 in South China. The 2008 LTRSF was characterized by persistent freezing, while the 2022 LTRSF featured more frequent rain-snow occurrences. Both extreme LTRSF events exhibit the typical circulation pattern of a blocking high coupled with a westward-shifted East Asia trough. However, significant differences in the intensity of cold air and moisture transport between the two events were observed. These differences were attributed to discrepancies in the India-Burma trough (IBT) and mid-high latitude trough-ridge patterns, which were influenced by Rossby wave activity flux propagation over Eurasia. Furthermore, our results indicate that the joint influence of La Niña and the positive North Atlantic Oscillation favored the occurrence of both events. The frequent rain-snow in 2022 event could be attributed to the synergistic effects of high sea ice anomalies in the northeastern East Siberian Sea-northern Chukchi Sea and La Niña. This combination could result in the deepened IBT and an anomalous anticyclone over the northwest Pacific, leading to increased precipitation. But remarkably, the Arctic sea ice anomalies alone play a negligible impact on LTRSF. These results can enhance our comprehension of LTRSF occurrence in South China and identify potential climate predictors for forecasting extreme LTRSF.