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气象:2020,46(10):1375-1384
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2020年春季我国气候特征及成因分析
洪洁莉,郑志海
(国家气候中心,中国气象局气候研究开放实验室,北京 100081)
Features and Possible Causes for the Boreal Spring Climate Anomalies in 2020
HONG Jieli,ZHENG Zhihai
(Laboratory for Climate Studies, National Climate Centre, CMA, Beijing 100081)
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投稿时间:2020-07-14    修订日期:2020-08-31
中文摘要: 2020年春季(3—5月),全国平均气温为11.5℃,为1961年以来历史同期第五位,全国大部地区气温接近常年同期或偏高。全国平均降水量为137 mm,较常年同期偏少4%,东部降水总体呈现“南北多中间少”的特征,东北大部、华北东部、内蒙古东部、江南南部和华南大部降水偏多,江淮地区降水显著偏少,季节内变化显著。春季(尤其是4—5月)中高纬度呈现“两槽一脊”分布,在对流层中层,乌拉尔山西北地区为负高度距平中心,贝加尔湖以西地区有很强的高度场正距平中心,日本海上空为高度场负距平;在对流层低层,中国东部大部盛行偏北风,经向度大。低纬度地区西北太平洋上空为反气旋式距平,西太平洋副热带高压偏强偏西偏南。这种环流形势有利于水汽在东北、华北东部和内蒙古东部辐合,降水偏多,而对我国东部大部分地区的水汽输送则较为不利。3月中高纬度的纬向型环流和偏强的西太平洋副热带高压的阶段性偏北有利于江南和华南降水偏多。2019/2020年中东太平洋发生一次弱El Ni〖AKn~D〗o事件,同时印度洋海温偏高,对维持春季西太平洋副热带高压的偏强偏西有利。2020年2—3月北大西洋偶极子海温距平与后期4—5月海温有较好持续性,前期北大西洋偶极子是预测4—5月贝加尔湖以西阻塞高压偏强的重要外强迫因子。
Abstract:In boreal spring 2020 (March-April-May), the average temperature in China is 11.5℃ ranking the fifth since 1961.The temperature is above or near average in most China. The mean precipitation is 137 mm, lower by 4% than climatology. The characteristic precipitation in East China is featured with enhanced precipitation in North and South China and suppressed in central China. The positive anomalies are mainly in most of Northeast, eastern North China, eastern Inner Mongolia, southern Jiangnan and most of South China. The negative is pronounced in the Jiang Huai Region. The sub seasonal variation of precipitation is significant. During boreal spring (mainly in April and May) in mid high latitudes, the signal of the pattern in the upper troposphere is two troughs and one ridge which is characterized by one blockage over west Lake Baikal and two troughs located over northwest Ural Mountains and the Sea of Japan, respectively. In low troposphere northerly anomaly prevails in eastern China with strong meridional circulation. An anticyclone in low troposphere is located at Northwest Pacific Ocean while the Western North Pacific subtropical high (WPSH) is much stronger and its ridge line is more southwestward. The water vapor is divergent over most Eastern China with deficient precipitation. In March 2020 the zonal circulation dominates mid high latitudes of Asia and WPSH exhibits stronger and northward, resulting in positive precipitation anomaly in Jiangnan and South China. The influence of tropical SST forcing shows that the Indian Ocean Basin warming (IOBW) and West Pacific play important roles in the sustained strengthening and westward trend of WPSH in spring in the decaying 2019/2020 weak Modoki ENSO. The North Atlantic SST dipole (NASD) mode shows good spatial persistence from February-March to April-May 2020. NASD in early boreal spring can be an important predictor that impacts the mid high latitude circulation with blocking over west Lake Baikal during April-May.
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基金项目:国家重点研发计划(2017YFC1502303)和国家自然科学基金项目(41875101、41530531、41875096、41975088和41575074)共同资助
引用文本:
洪洁莉,郑志海,2020.2020年春季我国气候特征及成因分析[J].气象,46(10):1375-1384.
HONG Jieli,ZHENG Zhihai,2020.Features and Possible Causes for the Boreal Spring Climate Anomalies in 2020[J].Meteor Mon,46(10):1375-1384.