Acta Geographica Sinica ›› 2009, Vol. 64 ›› Issue (3): 289-302.doi: 10.11821/xb200903004

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Summertime Temperature Variations in the Middle and Lower Yangtze River and Their Related Circulation Anomalies in the Eastern Hemisphere in the Past Five Decades

CAI Jiaxi1,2, GUAN Zhaoyong1,2, GAO Qingjiu1,2, LIN Xin3, QIAN Daili1,2   

  1. 1. School of Atmospheric Sciences,NUIST,Nanjing 210044,China;
    2. Jiangsu Key Laboratory of Meteorological Disaster,NUIST,Nanjing 210044,China;
    3. Fujian Climate Center,Fuzhou 350001,China
  • Received:2008-09-23 Revised:2008-12-15 Online:2009-03-25 Published:2009-03-25
  • Supported by:

    National Scientific and Technical Supporting Programs,Grant No.2007BAC29B02;Project of Jiangsu Key Laboratory of Meteorological Disaster,Grant No.KLME060101

Abstract:

Using the data of daily temperature from China Meteorological Administration and the NCEP/NCAR reanalysis data, we analyze the relationships between the summertime high/low temperature events in the middle and lower Yangtze River and the related circulation anomalies in the Eastern Hemisphere from 1960 to 2005. The summer temperature shows a significantly increasing trend, which are explained by the rise of daily minimum temperature in the past 50 years. In the major regions, the opposite scenarios are observed circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower Yangtze River. The emergence and maintenance of the anomalous circulations are found to be related to three wave train related teleconnection patterns. The anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. Influences of the long wave surfaxe radiation on the air temperature are found to be stronger in the nighttime than in the daytime. Both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating (cooling) caused by the vertical thermal advection as well as the diabatic heating (cooling) caused by diabatic processes can explain the formation of the high (low) temperature events in the middle and lower Yangtze River in boreal summer.

Key words: the middle and lower Yangtze River, summertime temperature variations, circulation characteristics