ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 45 Issue 10 > 2019,45(10):1483-1493. DOI:10.7519/j.issn.1000-0526.2019.10.015 Prev Next
Features and Possible Causes for the Spring Climate Anomalies in 2019
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Abstract:
In spring 2019 (March-April-May, MAM), the average temperature in China is 11.5℃, ranking the fourth in the same period since 1961. The average precipitation in China is 148.7 mm (near normal), with profound spatial differences. The precipitation is more than normal over Northeast China, east part of Northwest China and South China, but less than normal over Huanghuai, Jianghuai and most of Yunnan Province in MAM 2019. The MAM precipitation in Yunnan is the least since 1961. High temperature and uneven spatial distribution of precipitation lead to the coexistence of drought and flood disasters in MAM 2019. The sub-seasonal climate variability in spring 2019 is significant, showing the characteristics of the transition period from East Asian winter monsoon circulation to summer monsoon circulation. The high temperature in most China in spring (especially in March and April) is obviously affected by the mid-latitude circulation anomalies pattern. The Ural Mountains and to their north regions are the center of negative height anomaly, while the areas east of Ural Mountains to Lake Baikal are the center of positive height anomaly. Such an anomalous circulation pattern is very helpful to the overall high temperature in China. The atmospheric circulation systems present an obvious response to the tropical SST anomalies in MAM 2019. The western North Pacific subtropical high (WPSH) is strong, westward and southward extending, which basically determines the spatial pattern of spring precipitation anomaly in China. The intensity and location of WPSH not only directly control the pattern of precipitation anomaly in southern China, but also affect the distribution of precipitation over northern China through the interaction of circulation anomalies in mid-high latitudes. Further analysis on the influence of tropical SST forcing shows that the warming of tropical Indian Ocean SST plays a more important role in the sustained strengthening and westward trend of WPSH in the El Ni〖AKn~D〗o decaying spring. The influence of the El Ni〖AKn~D〗o event on the intensity of WPSH gradually weakens in spring, and the effect on the north-south position of WPSH becomes more obvious.
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