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江西省冬季大雪气候概况和环流特征分析
引用本文:郑婧,许爱华,刘波,许彬.江西省冬季大雪气候概况和环流特征分析[J].气象与减灾研究,2009,32(1):32-38.
作者姓名:郑婧  许爱华  刘波  许彬
作者单位:江西省气象台,江西,南昌,330046
基金项目:中国气象局气象新技术推广项目,江西省气象局重点科研项目 
摘    要:利用NCEP2.5°×2.5°再分析资料和常规观测资料,对1980--2008年江西省50次区域性大雪过程的气候概况、环流演变、热力层结、影响系统特征进行归纳分析。结果表明,江西省冬季大雪具有明显的年际、月际变化特征,冷冬年为大雪天气的多发年,进入暖冬期后,则有减少的趋势;空间变化上,出现大雪的频次基本上呈现出自西北向东南逐渐减少的特征,各地区积雪分布极不均匀。大雪期间,极涡、阻塞高压异常强而稳定,中低纬锋区异常强盛;超长波的稳定形势有利于天气背景的维持,造成连续性大雪。有80%的比例存在阻塞高压,以贝加尔湖阻塞高压最多;有70%的比例是受南支槽影响,当南支槽与中高纬度转竖的横槽同位叠加时,有利于引导极地强冷空气向副热带地区爆发,形成江西大范围降雪天气。对流层中低层多存在切变线,雪区位于冷式切变线以南1—3个纬距内或暖式切变附近,雪区伴随着暖切的南移而扩展;700hPa西南气流强盛,急流轴最大风速超过16m/s;当850hPa同时存在切变线时,降雪天气更剧烈。有98%的比例对流层中低层存在逆温,逆温高度平均在700-925hPa;温度垂直分布一般具有1000hPa温度≤0℃,925—850hPa温度≤-2℃,700hPa温度≤-2℃的特点。地面冷空气多为中路,蒙古冷高压异常强大,为降雪的产生创造良好的热力条件。

关 键 词:冬季大雪  气候概况  环流  热力结构

ANALYSIS OF THE CLIMATE AND CIRCULATION CHARACTERISTICS OF HEAVY SNOW IN JIANGXI
Zheng Jing,Xu Aihua,Liu Bo,Xu Bin.ANALYSIS OF THE CLIMATE AND CIRCULATION CHARACTERISTICS OF HEAVY SNOW IN JIANGXI[J].Meteorology and Disaster Reduction Research,2009,32(1):32-38.
Authors:Zheng Jing  Xu Aihua  Liu Bo  Xu Bin
Institution:Zheng Jing,Xu Aihua,Liu Bo,Xu Bin Jiangxi Provincial Meteorological Observatory,Nanchang 330046,China
Abstract:Based on NCEP 2.5°×2.5°reanalyzed data and daily observation data, the characteristics of climatic situation, circulation evolution, thermal stratification and influencing system of 50 regional heavy snow events from 1980 to 2008 in Jiangxi were summarized and analyzed. The results showed that: (1) Heavy snow events in Jiangxi presented noticeable inter-annual and inter-monthly variations and tended to occur more frequently in cold-winter years than in warm-winter years. As to the spatial variation, the frequency of heavy snow was characterized by the distribution of gradually inducing from the northwest to the southeast, and the snow covers were very uneven. (2) During heavy snow periods, the blocking high and the polar vortex were extremely strong and stable, and the frontal zone in mid-low latitude was extremely powerful. Thus, the stabilized ultra long wave was favorable to the maintenance of the synoptic situation for heavy snow events. ( 3 ) 80% heavy snow events were associated with blocking highs, most of which were Baikal Lake blocking highs. While southern system were extraordinarily strong and active, and 70% of the events were associated with southern trough within 100--115°E. When a southern trough was coupled with a transversal trough turning into upright at mid-high latitude, the polar cold air was likely to break out towards subtropical area and initiate large area heavy snow event. (4) Most heavy snow events were associated with shear line at mid-low layer. Normally, the shear line located within 25--32°N, with a snowing region 1--3 latitudes distance southern to a cold shear line or at the neighborhood of a warm shear line. There was significant southwest jet with an over 16 m/s axis at 700 hPa. If there was a shear line at 850 hPa simultaneously, the .snow would be heavier. (5) 98% of the events were accompanied by inversion layers in the troposphere. The average height of inversion layer was located between 925 and 700 hPa. The vertical distribution of temperature was characterized by ≤0℃ at 1 000 hPa, ≤-2℃ at 925--850 hPa and ≤-2℃ at 700 hPa. (6) Mostly, the surface cold air was from the middle area where an extremely strong Mongolia cold high offered a favorable thermal condition for snowfall.
Keywords:Heavy snow in winter  Climatic general situation  Circulation characteristics  Characteristics of thermal stratification    
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