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长江以南和东北冬季湿冷型复合极端天气的对比

Comparative analysis of wet-cold compound extremes in Southern China and Northeastern China during the winter

  • 摘要: 利用1962—2022年基于中国台站观测的高分辨率格点化逐日2 m气温、相对湿度以及降水资料,客观定义了有利于低温雨雪冰冻天气形成的湿冷型复合极端天气,进一步对比分析了长江以南与东北湿冷型复合极端天气的异同。结果表明:(1) 长江以南地区是我国湿冷型复合极端天气最高发的地区,年平均发生频次可达30 d以上;东北地区为又一高发中心,年平均发生频次为10 d以上。(2) 长江以南的湿冷型天气以中等强度降温和高湿度为主要特征,平均持续时间为5.2 d,影响范围约为30万km2;而东北地区以强降温和中等湿度为主,平均持续时间为3.3 d,影响范围约为38.3万km2。(3) 长江以南的区域性湿冷型复合极端事件的强度和影响范围以年际变化为主要特征,而东北地区的区域性湿冷型复合极端事件的强度和影响范围近30 a (1992—2021年)相比于前30 a (1962—1991年)分别增加了100%和43.5%,相对湿度变率的显著增加是造成湿冷型复合极端事件增强的重要原因之一。本文研究结果有助于进一步提升对我国南北方区域湿冷型复合极端天气差异的认识。

     

    Abstract: Based on high-resolution gridded daily observations of 2-meter air temperature, relative humidity, and precipitation from Chinese meteorological stations during 1962-2022, this study objectively defines wet-cold compound extremes (WCCE) conducive to low-temperature freezing rain and snow weather, and further compared the WCCEs between northeastern China and south of the Yangtze River. The results indicate that: (1) WCCEs frequently occur over south of the Yangtze River, with an average frequency exceeding 30 days per year. Northeastern China is another hotspot of WCCEs, with an average occurrence of more than 10 days. (2) The WCCEs south of the Yangtze River are characterized by moderate temperature drop and high humidity, with an average duration of 5.2 days and affected area of approximately 300,000 km2. In contrast, northeastern China experiences stronger low temperature and moderate humidity, with a shorter average duration of 3.3 days and smaller affected areas (383,000 km2). (3) The intensity and spatial extent of regional WCCE events south of the Yangtze River mainly exhibit interannual variability. By contrast, the intensity and spatial extent of regional WCCE events in northeastern China have increased by 100% and 43.5% over the past 30 years (1992-2021) relative to the preceding 30-year period (1962-1991), respectively. This intensification of WCCE is intimately associated with the increased variability of relative humidity in this region. The findings of this study are significant in improving our understanding of the differences in WCCE between southern and northern regions of China.

     

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