近40年中国冬季寒潮的气候特征及大气环流异常

Climatology of Winter Cold Waves and Associated Atmospheric Circulation Anomalies in China During the Last 40 Years

  • 摘要: 利用1980—2023年高分辨率中国气象站观测数据,根据寒潮标准及强度指数,对中国寒潮事件的强度及影响区域进行客观分类,探讨全国性、区域性寒潮事件的时空变化特征和环流演变。结果表明:近40年我国冬季寒潮频次呈显著减少趋势,其影响范围扩大,而强寒潮的强度呈显著增加趋势,且年际变化幅度明显增大。中国寒潮冷空气主要来源于新地岛东南地区,路径因寒潮类型而异。分析全国型、东北华北型和西北华北型寒潮前期和同期大气环流异常特征发现:格陵兰岛的异常深厚暖高压是全国型寒潮的重要前兆,欧亚大陆对流层中高层纬向波列是其爆发的显著特征;东北华北型寒潮与冷涡在中低纬度异常高压系统阻挡下的东移有关;西北华北型寒潮与东欧平原上空暖性高压脊的发展及欧亚大陆两脊一槽的形势密切相关。所有类型寒潮爆发前均有乌拉尔阻塞高压的维持和西伯利亚地区冷空气的堆积。

     

    Abstract: Based on daily high-resolution temperature observations at 1941 meteorological stations in China from 1980 to 2023, stations reaching standard for cold wave and 418 cold wave processes (including 152 strong cold waves processes) in winter are identified according to the monitoring indices of cold air processes. And cold wave processes are objectively classified according to their intensity and influencing areas using K-means++ clustering method. The temporal and spatial characteristics of the single-station cold waves and 418 cold wave events are discussed. Results show that the frequency of cold waves in the high affecting areas of China has not increased significantly but has shown a decreasing trend over the last 40 years. The increasing trend of frequency and intensity of single-station cold waves in the middle-lower reaches of the Yangtze River Plain is significant. Additionally, the intensity of single-station cold waves in South China is also noticeably enhanced. The frequency of winter cold wave events in China has decreased significantly in the last 40 years with an expanding range of influence, while the intensity of strong cold wave events has increased significantly, accompanied by a marked increase in the amplitude of interannual variations. The cold air associated with cold waves in China mainly originates from the southeast of Novaya Zemlya, and its trajectory varies depending on the type of cold wave. Based on the fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis data (ERA5), characteristics of atmospheric circulation anomalies in the preceding and the simultaneous period for cold wave processes in the countrywide, Northeast-North China and Northwest-North China are analyzed. It is found that the deep warm high pressure in Greenland is an important precursor of the countrywide cold wave, and the zonal wave train in the middle and upper troposphere of Eurasia is a prominent feature of the cold wave outbreak. The cold wave in Northeast-North China is related to the eastward movement of the cold vortex under the block of anomalous high-pressure system in the mid-low latitudes. The cold wave in Northwest-North China is closely related to the development of a warm high ridge over the East European Plain and the circulation situation of two-ridge-one-trough in mid-high latitudes of Eurasia. All types of cold waves are preceded by the maintenance of the Ural blocking high and the accumulation of cold air in Siberia.

     

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