In this paper, we investigate the influence of the winter NAO on the multidecadal variability of winter East Asian surface air temperature (EASAT) and EASAT decadal prediction. The observational analysis shows that the winter EASAT and East Asian minimum SAT (EAmSAT) display strong in-phase fluctuations and a significant 60–80-year multidecadal variability, apart from a long-term warming trend. The winter EASAT experienced a decreasing trend in the last two decades, which is consistent with the occurrence of extremely cold events in East Asia winters in recent years. The winter NAO leads the detrended winter EASAT by 12–18 years with the greatest significant positive correlation at the lead time of 15 years. Further analysis shows that ENSO may affect winter EASAT interannual variability, but does not affect the robust lead relationship between the winter NAO and EASAT. We present the coupled oceanic-atmospheric bridge (COAB) mechanism of the NAO influences on winter EASAT multidecadal variability through its accumulated delayed effect of ∼15 years on the Atlantic Multidecadal Oscillation (AMO) and Africa-Asia multidecadal teleconnection (AAMT) pattern. An NAO-based linear model for predicting winter decadal EASAT is constructed on the principle of the COAB mechanism, with good hindcast performance. The winter EASAT for 2020–34 is predicted to keep on fluctuating downward until ∼2025, implying a high probability of occurrence of extremely cold events in coming winters in East Asia, followed by a sudden turn towards sharp warming. The predicted 2020/21 winter EASAT is almost the same as the 2019/20 winter.
The north China July precipitation (NCJP) accounts for the largest proportion of annual total precipitation in north China and displays a significant decadal variability of a cycle about 20‐year at least from the past 40 years. There is a significant negative correlation between the July northern North Atlantic sea surface temperature (NNASST) and NCJP on decadal scale. When the detrended July NNASST anomaly is in negative phase, the NCJP anomaly is in positive phase, and vice versa. We present the coupled oceanic–atmospheric bridge (COAB) mechanism of the July NNASST influences on NCJP decadal variability via the Eurasian decadal teleconnection (EAT) pattern: the NNASST stimulates the EAT pattern which regulates circulation anomalies in north China and its surrounding regions, and finally regulates precipitation anomalies in north China by influencing the local water vapour transport. In addition, a preliminary analysis about the causes of the super‐abnormal NCJP in 2021 indicates that the super‐abnormal NCJP in 2021 is not just the decadal role of the NNASST on NCJP, may be the combined influence of the WPSH in the northeastern of north China, the abnormal high pressure in the northwest and the low‐pressure cyclone in the south in the rainy decadal background.
<p>In this paper, we investigate the influence of the winter NAO on the multidecadal variability of winter East Asian surface air temperature (EASAT) and its decadal prediction. The observational analysis shows that the winter EASAT and East Asian minimum SAT (EAmSAT) display strong in-phase fluctuations and a significant 60&#8211;80-year multidecadal variability, apart from a long-term warming trend. The winter EASAT experienced a decreasing trend in the last two decades, which is conducive to the occurrence of winter extremely cold events in East Asia in recent years. The winter NAO leads the detrended winter EASAT by 12&#8211;18 years with a maximumly significant positive correlation at the leading time of 15 years. Further analysis shows that ENSO may affect winter EASAT interannual variability, but does not affect the robust leading relationship between the winter NAO and EASAT. We present the coupled oceanic-atmospheric bridge (COAB) mechanism of the NAO influences on winter EASAT multidecadal variability through its accumulated delayed effect of ~15 years on the Atlantic Multidecadal Oscillation (AMO) and Africa&#8211;Asia multidecadal teleconnection (AAMT) pattern. Based on the COAB mechanism an NAO-based linear model for predicting winter decadal EASAT is constructed, with good hindcast performance. The winter EASAT for 2020&#8211;2034 is predicted to keep on fluctuating downward until ~2025, implying a high probability of occurrence of extremely cold events in coming winters in East Asia, and then turn towards sharp warming. The predicted 2020/21 winter EASAT is almost the same as the 2019/20 winter.</p><p><strong>Keywords:</strong> winter East Asian surface air temperature (EASAT), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), Africa-Asia multidecadal teleconnection (AAMT) pattern, coupled oceanic-atmospheric bridge (COAB), multidecadal variability.</p>
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