Attribution of Persistent Precipitation in the Yangtze-Huaihe River Basin during February 2019
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• Original Paper •
Attribution of Persistent Precipitation in the Yangtze–Huaihe River Basin during February 2019 Zhixuan WANG1, Jilin SUN*1,2, Jiancheng WU3, Fangyue NING1, and Weiqi CHEN4 1College 2Key
of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China
laboratory of Physical Oceanography, Ocean University of China, Qingdao 266100, China
3Zhangzhou 4Huaan
Meteorological Observatory, Zhangzhou Meteorological Bureau, Zhangzhou 363000, China Meteorological Observatory, Huaan Meteorological Bureau, Zhangzhou 363800, China (Received 24 April 2020; revised 27 July 2020; accepted 10 August 2020) ABSTRACT
In February 2019, a month-long persistent precipitation event occurred in the Yangtze–Huaihe River basin. The geopotential height field that affected the duration of this frontal rainfall was divided into a high-latitude part and a lowlatitude part for analysis. In the high-latitude part, a two-wave structure led to quasi-stationary circulation, and the change of both the blocking high pressure and Arctic Oscillation phase caused cold air to invade South China continuously and changed the frontal position. In mid-to-low latitudes, the persistent precipitation showed quasi-biweekly oscillation characteristics. The so-called “subtropical high–precipitation–anticyclone ” (SHPA) feedback mechanism blocked the circulation systems in the mid-to-low latitudes and provided a continuous supply of water vapor for precipitation. As for the effect of sea surface temperature, the western North Pacific anomalous anticyclone stimulated by El Niño strengthened the intensity of the southerly wind and provided support for the redevelopment of the anticyclone system in the SHPA feedback mechanism. The sea surface temperature anomaly in the South China Sea provided sensible heating for precipitation, and convergent rising airflow was conducive to the occurrence of precipitation. Additionally, the SHPA mechanism provides a reliable basis for the prediction of persistent precipitation in winter in the mid-to-low latitudes. Key words: persistent precipitation, feedback mechanism, latent heat Citation: Wang, Z. X., J. L. Sun, J. C, Wu, F. Y. Ning, and W. Q. Chen, 2020: Attribution of persistent precipitation in the Yangtze–Huaihe River basin during February 2019. Adv. Atmos. Sci., 37(12), 1389−1404, https://doi.org/10.1007/s00376020-0107-6. Article Highlights:
• Attribution analysis of persistent precipitation throughout February 2019 in the Yangtze–Huaihe River basin was carried out.
• A “subtropical high–precipitation–anticyclone” feedback mechanism is identified. • A new method for forecasting persistent anomalous weather is proposed.
1. Introduction In February 2019, a month-long persistent rainfall event occurred in the Yangtze–Huaihe River basin (YHRB), China. During this period, the daily precipitation was substantially higher than in other years and the precipitation anomaly intensity in the central area of the rainfall reached a maximum of 6 mm d−1 (Fig. 1a). Additionally, the
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