ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 50 Issue 4 > 2024,50(4):499-513. DOI:10.7519/j.issn.1000-0526.2024.022602 Prev Next
Features and Possible Causes of Abnormal Climate over China in Autumn 2023
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Abstract:
Based on the NCEP/NCAR reanalysis data and climate observations from 2400 stations of China, the characteristics of climatic anomalies over China in autumn 2023 and the possible causes are analyzed. The results denote that, in autumn 2023, the average temperature in China peaked the record in the same period since 1961, and the average precipitation was close to the climatic mean, but had uneven spatial distribution and significant intra-seasonal variability. The circulation in the mid-high latitudes of Eurasia showed a “negative-positive-negative” pattern on the seasonal mean scale, leading to the abnormal warming in China. In September, the circulation was in a “positive-negative-positive” pattern that caused the frequent activity of the trough near Balkhash Lake and the increase of precipitation in Northwest China; in October, the “negative-positive-negative” pattern of circulation caused further warming in northern China; and in November the circulation pattern of “positive in west and negative in east” formed, enhancing the cold air in the east and causing the temperature in Northeast 〖JP2〗China to drop to below normal and precipitation〖JP〗 to be more than normal. The Western Pacific subtropical high (WPSH) was stronger and more westward than usual overall, and its ridge line swung frequently in the meridional direction, that is, the ridge line was abnormally further north than usual in September, further south than usual in October and close to normal position in November. The India-Burma trough was significantly stronger in September and near normal during October-November. In September, the stronger Indo-Burma trough and the northerly WPSH jointly contributed to the heavy〖JP2〗 rainfall in the region between the middle and lower reaches of Yangtze〖JP〗 River and the lower reaches of Yellow River. The basic water vapor transport condition in eastern China became negative from October to November. In addition, typhoon activities in southern coastal area of China were frequent in September and October, resulting in more precipitation in South China. These results reveal that the climate anomaly in autumn 2023 was significantly affected by the intra-seasonal variation of the atmosphere, and it did not match the typical responses to the tropical SST anomaly.
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