ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 38 Issue 11 > 2012,38(11):1367-1377. DOI:10.7519/j.issn.1000-0526.2012.11.006 Prev Next
Abnormality of General Circulation with LFO During the Torrential Rainstorms over Southern China in 2010
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Abstract:
By using NCEP/NCAR daily reanalysis data and NCC station precipitation data, the authors analyze the abnormality of general circulation with LFO during the torrential rainstorms over southern China in 2010 with the application of multivariate empirical orthogonal function (MV EOF). Results show that: the East Asian summer monsoon to be exceptionally weak, the West Pacific subtropical anticyclone to be exceptionally southerly, the emergence of three monsoon surges, the abnormal activities of upper level westerly jet and divergence field and their interactions with one another, are the main affecting systems of precipitation abnormality over southern China in 2010. To the MV EOF spatial distributions of wind and precipitation fields, the centers of low frequency precipitation always correspond to those of 200 hPa flow divergence and 850 hPa convergence. The first MV EOF mode of precipitation field reflects the climatic evolution of East Asian summer monsoon, while the second and third modes reflect the LFOs on different time scales of summer monsoon during the seasonal advancing process. The second mode is in positive phase of LFO during the first half of July while the third mode during the middle and later part of June, so that the ends of Jiang huai Meiyu season and early flood season of southern China are put off and Meiyu precipitation in the middle and lower reaches of the Yangtze River is enhanced. The climatic evolution of summer monsoon coincided with LFO ultimately leads to the frequent rainstorms over southern China in 2010.
Keywords:
torrential rainstorms, abnormality of circulation, low frequency oscillation (LFO), MV EOF (multivariate empirical orthogonal function)
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