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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 between south of the Yangtze River 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,客观定义有利于低温雨雪冰冻天气形成的湿冷型复合极端天气,对比分析长江以南和东北地区湿冷型复合极端天气的异同。结果表明:(1) 长江以南是我国湿冷型复合极端天气高发区,年均发生频次达30 d以上;东北地区为另一高发中心,年均发生频次达10 d以上。(2) 长江以南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5.2 d,影响范围约30万km2;东北地区以强降温和中等湿度为主,平均持续时间3.3 d,影响范围约38.3万km2。(3) 长江以南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,东北地区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大是造成湿冷型复合极端事件增加的重要原因之一。上述研究结果有助于加深对我国南北地区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 (WCCEs) 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 are as follows. (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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