Abstract:Based on the observational datasets from National Meteorological Information Center (NMIC) of China and NCEP/NCAR reanalysis, the characteristics of spatial-temporal distributions of climate anomalies in winter 2023/2024 and its possible mechanisms are analyzed. In the winter of 2023/2024, the average temperature in China was 0.3℃ higher than climatology. The fluctuation of temperature is significant, with warmer early winter and colder late winter. The average precipitation was 19.8% more than climatology, with above normal precipitation for most parts of central and eastern China. The intensity of East Asian winter monsoon and Siberian high was near normal. The East Asian trough was weak than normal. The 500hPa geopotential height in the middle and high latitudes of Eurasia was low in the west and high in the east, with significant subseasonal fluctuation. Zonal atmospheric circulation prevails in December 2023 and January 2024, and transition to meridional patterns in February 2024, which was favorable for cold surge outbreak. In response to the synergistic effect of El Ni?o mature phase, warm tropical Indian and Atlantic ocean, cold phase of Pacific decadal oscillation, an anomalous lower tropospheric anticyclone developed in the western North Pacific, the western Pacific subtropical high intensified and extends westward, a Rossby wave train propagates along Asian westerly jet in the upper troposphere, which was favorable for the water vapor transport into central and eastern China. The confluence of cold air intrusion and warm air leads to frequent snow and rain process in central and eastern China.