Predictability of China winter temperature under different intensities of La Nina events in seasonal climate forecast models

In this study, we focus on the features and predictability of winter 2-m air temperature (t2m) over China under different intensities of La Nina events. The seasonal and intraseasonal prediction skills of winter t2m over China are examined by four state-of-art seasonal climate forecast models. The results show that the China winter t2m anomaly is sensitive to the intensity of La Nina. Strong and moderate (S/M) La Nina events are often accompanied by cold winter over China, while a positive anomaly of mean t2m over China frequently occurs in the weak La Nina events. The intensity difference of the East Asian winter monsoon (EAWM) results in this discrepancy. All models have a slightly higher anomaly correlation coefficient (ACC) for the S/M La Nina than that for the weak La Nina in leading 1 month (LT1). Both individual models and MME exhibit higher skills of anomaly sign consistency rate (ASCR) for the S/M La Nina, which implies that models predict t2m anomaly over China more accurately in the S/M La Nina events. Furthermore, the winter t2m over China presents larger intraseasonal variability for the S/M La Nina than that for the weak La Nina. Models can capture the t2m anomaly over China more accurately when the temperature varies gently with small intraseasonal variability during winter for the S/M La Nina.