2015/2016和1997/1998超强El Niño衰减年我国夏季降水异常的比较
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国家自然科学基金资助项目(41641042;41675039;41305039;41375047;41305079;91537213);江苏高校优势学科建设工程项目(PAPD)


Comparison between anomalies of summer rainfall in China in decaying years during super El Niño events of 2015/2016 and 1997/1998
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    摘要:

    El Niño可通过海-气相互作用遥相关型影响东亚季风,进而影响中国气候,是中国短期气候最重要的预测指标之一。典型的El Niño事件通常在春、夏季开始,在秋、冬季成熟,在下一年的春、夏季消退,考虑到海-气作用的滞后效应,El Niño事件甚至可以在消退时期对东亚大气环流系统造成影响。因此,利用中国160站的逐月降水资料、NCEP/NCAR再分析资料以及美国NOAA提供的全球海温数据,对比分析了2015/2016年和1997/1998年典型El Niño衰减年我国夏季降水和东亚环流特征的差异,并讨论了造成差异的可能原因。结果表明:1)2016年和2008年夏季降水都大范围偏多,2016年夏季降水异常更为集中,但降水强度不及1998年。2)2016年降水的季节推进特征不明显。1998年6-8月的降水逐渐从南向北推进,与传统的季风降水演变进程较为一致。3)2016年和2008年我国夏季降水的差异与副热带高压的变化有直接的关系。1998年6-7月副热带高压较2016年同期偏西偏南,而2016年8月副热带高压更为偏西并明显比气候平均偏北。4)1997/1998年El Niño事件中的赤道西太平洋异常冷海温比较强盛,而2015/2016年基本表现为偏暖,可能是造成1998年6-7月副热带高压较2016年同期偏西偏南的原因。

    Abstract:

    The El Niño Southern Oscillation is the most significant interannual scale signal of global tropical air sea systems.It can affect the East Asian monsoon system through the teleconnection form of air-sea interaction,following which it has an impact on climate in China.Therefore,El Niño is one of the most important predictors of short-term climate in China.El Niño events typically begin in the spring and summer,mature in the autumn and winter,and subside in the spring and summer of the following year.Considering the hysteretic response of the atmosphere to the ocean,El Niño can have an influence on the atmospheric circulation over East Asia,and even the precipitation in China in decaying years of El Niño.Therefore,the anomalies of summer rainfall in China and atmospheric circulation over East Asia in the decaying years of two super El Nino events(2015/2016 and 1997/1998) were compared,in order to improve the understanding of the relationship between El Niño events and climate anomalies in China,as well as to provide a reference for short-term climate prediction.Specifically speaking,the percentage of precipitation anomaly in China,water vapor flux anomaly,anomaly of water vapor flux divergence,geopotential height anomaly,western end of the ridge and position of the ridge of the subtropical high and sea surface temperature anomaly in the decaying years of two super El Nino events were analyzed,by means of the monthly mean precipitation data of 160 meteorological observation stations in China,along with the circulation index,Indian Ocean Basin-wide Warming index from the National Climate Center of China Meteorological Administration,monthly mean geopotential height,wind,specific humidity and surface pressure from the American National Centers for Environmental Prediction,and the Optimum Interpolation Sea Surface Temperature version 2 data from the American National Oceanic and Atmospheric Administration.The results are as follows.Summer rainfall frequently occurs on a large scaleand flood disaster is serious in 2016 and 2008.However,summer rainfall anomalies in the two years also have different characteristics.The area of summer precipitation positive anomaly in 2016 is more concentrated than that in 1998,but the intensity of precipitation in 2016 is lower than that in 1998.In June and July 2016,the positive anomalous precipitation is maintained in the area to the north of the Yangtze River.By August,the positive anomalous precipitation area is significantly reduced.There is only a small range of rainfall in southern China,which is mainly caused by typhoons.Therefore,the seasonal moving features of the rain band are not significant,while the area of the rainfall positive anomaly gradually moves from south to north during the summer of 1998,which is consistent with the traditional process of the precipitation of the monsoon.The difference of summer rainfall in 2016 and 2008 in China is closely related to the difference of the anomaly of water vapor flux divergence caused by the anomaly of atmospheric circulation.The Pacific Subtropical High in summer 1998 is more robust and located more to the west than that of summer 2016,and the ridge of the Pacific Subtropical High in summer 1998 is more to the south than that of 2016.Moreover,the Pacific Subtropical Highin June and July is located more to the southwest in 1998 than 2016,while the Pacific Subtropical High in August is more to the west in 2016 than 1998,and more to the north than usual.These differences of the Pacific Subtropical High can partially explain the differences between the 2016 and 2008 summer rainfall in China.Further more,one possible reason for the difference of the Pacific Sub tropical High in June and July in 1998 and 2016 is that the Western Equatorial Pacific sea surface temperature in 1997/1998 is colder than that in 2015/2016.The difference of the North western Equatorial Pacific sea surface temperature may also attribute to the difference of the Subtropical High in August of 1998 and 2016.

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郭栋,王琳玮,李震坤,苏昱丞,覃皓,黄莹,2016.2015/2016和1997/1998超强El Niño衰减年我国夏季降水异常的比较[J].大气科学学报,39(6):835-844. GUO Dong, WANG Linwei, LI Zhenkun, SU Yuchen, QIN Hao, HUANG Ying,2016. Comparison between anomalies of summer rainfall in China in decaying years during super El Niño events of 2015/2016 and 1997/1998[J]. Trans Atmos Sci,39(6):835-844. DOI:10.13878/j. cnki. dqkxxb.20160828010

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  • 收稿日期:2016-08-28
  • 最后修改日期:2016-11-08
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  • 在线发布日期: 2016-12-27
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