The ENSO Prediction in 2021 Winter Based on the FIO-CPS v2.0

In the winter of 2020 (from December 2020 to February 2021)，the observed Sea Surface Temperature (SST) in the equatorial eastern Pacific continues to decrease，and a La Nina event is developed. In the spring of 2021，the SST increases， and the ENSO ( El Nino-Southern Oscillation) returns to neutral conditions. The latest observations suggest that SST in the equatorial eastern Pacific has dropped again since autumn 2021. Whether La Nina events will happen again in the coming winter of 2021, and how does this affect the winter climate? In this paper, the winter conditions of ENSO, surface air temperature, and precipitation over China are predicted by the FIO-CPS v2.0, a short- term climate prediction system developed by the First Institute of Oceanography, Ministry of Natural Resources of China. Prediction results starting from October 1 of 2021 show that the Nino 3.4 will be below一0.5 °C from October to December of 2021，which indicates a weak La Nina event will appear with the lowest value in November. In the spring of 2022，the ENSO will return to neutral state. Under the background of La Nina, the surface air temperature will decrease over most parts of China in November 2021，except for the Qinghai- Tibet Plateau, southwest region, southeastern coastal areas and Taiwan of China. After that，the surface air temperature will be warm in the north of China from December 2021 to February 2022，and the southernparts of China may experience a cold winter. Moreover, there will be more precipitation in the south and less in the north in the coming early winter, and the pattern will be reversed in the late winter of 2021.Note that there are significant differences in precipitation prediction results among different ensembles, indicating the higher uncertainty for precipitation prediction than that of air temperature.