Multidecadal Changes in the Influence of the Arctic Oscillation on the East Asian Surface Air Temperature in Boreal Winter

Abstract

The time-varying influences of the wintertime Arctic Oscillation (AO) on the concurrent East Asian surface air temperature (EAT) are investigated based on JRA-55 reanalysis data. Results reveal that there are multidecadal variations in the influences of wintertime AO on the EAT during 1958–2018. Before the mid-1980s, the impact of winter AO on the simultaneous EAT is weak and confined northward of 40° N over East Asia. After the mid-1980s, by contrast, the winter AO’s influence is stronger and can extend southward of 25° N over East Asia. The multidecadal variations of the winter AO–EAT relationship are mainly modulated by the magnitudes of the North Pacific center of the winter AO. During the periods with strong North Pacific center of the winter AO, in association with the positive phase of the winter AO, the low-level southeasterly anomalies on the west side of the anticyclone over North Pacific bring warm air from the ocean to East Asia and lead to a significant winter AO–EAT relationship. In contrast, the southerly anomalies are weak and even reversed to northerly over the coast of East Asia during the periods with weak North Pacific center of winter AO, which confines the influence of winter AO on northern East Asia and lead to an insignificant winter AO–EAT relationship. Our finding provides new insight into the understanding of the decadal changes of AO’s impacts on the regional climate.

The 2020 Siberian heat wave

“…The multi‐year regression shows the main features of winter‐early spring 2020: an extensive positive relation from Europe through East Asia and a bimodal maxima distribution over Europe and East Asia. Eurasian surface air temperature anomalies have also been shown to be associated with the persistence of large‐scale atmospheric circulation anomaly patterns over the North Atlantic and Eurasia, featuring a combination of the North Atlantic Oscillation (NAO)/AO and the Scandinavian pattern (SCA), from winter to spring (Gong et al ., 2019; Wu and Chen, 2020). NAO was greater than 1.0 for January–March 2020 and SCA was strongly negative (negative heights over Scandinavia and correlated with positive Siberian temperatures) for January–May 2020.…”

“…The multi-year regression shows the main features of winterearly spring 2020: an extensive positive relation from Europe through East Asia and a bimodal maxima distribution over Europe and East Asia. Eurasian surface air temperature anomalies have also been shown to be (Gong et al, 2019;Wu and Chen, 2020). NAO was greater than 1.0 for January-March 2020 and SCA was strongly negative (negative heights over Scandinavia and correlated with positive Siberian temperatures) for January-May 2020.…”

Influence of the NAO on Wintertime Surface Air Temperature over East Asia: Multidecadal Variability and Decadal Prediction

“…Zhang et al (2019) also emphasized the important impacts of equatorial La Niña and mega-La Niña on the cold southern mode of winter East Asian SAT (EASAT). Some studies suggested that the Arctic Oscillation (AO)/Northern Hemisphere (NH) Annular Mode (NAM) could contribute to anomalously low SAT in the winter NH mid-latitudes as well as China (Gong et al, 2001;Wu and Wang, 2002;Jeong and Ho, 2005;Li, 2005a, b;Wang and Chen, 2010;Ha et al, 2012;Sun and Li, 2012;Chen et al, 2013;Ding et al, 2014;Yun et al, 2014;Zuo et al, 2015;Li, 2016;Li et al, 2019a) and the springtime extreme low temperature events in northeast China (Yin et al, 2013;Li, 2016). In addition, there are other responsible factors for the winter EASAT, e.g., the autumn and winter Arctic sea ice (Wu et al, 2011a(Wu et al, , 2011bLi and Wu, 2012;Li et al, 2019c;Zhang et al, 2020), autumnal North Pacific sea surface temperature (SST) (Kim and Ahn, 2012), two types of El Niño (Hu et al, 2012), Southern Hemisphere annular mode (SAM) (Wu et al, 2009(Wu et al, , 2015Zheng et al, 2014;Li, 2016), Eurasian snow cover (Yu et al, 2018), etc.…”

Role of the Moist and Dry Components of Moist Isentropic Mass Circulation in Changing the Extratropical Surface Temperature in Winter

“…The total column air mass, which is proportional to the surface pressure, shows positive (negative) anomalies in the high (mid‐) latitudes associated with WB_D + events (Figure 4c), suggesting a negative phase of the Arctic Oscillation. A negative Arctic Oscillation is well known to be accompanied by stronger planetary wave activity, favoring the stronger southward transport of cold air (Chen et al., 2005; Yu et al., 2015b; H. Gong et al., 2019a, 2019b). By contrast, a positive Arctic Oscillation, which corresponds to stronger westerly winds in the extratropics (Thompson & Wallace, 1998, 2000), accompanies WB_M + events, promoting the development of synoptic‐scale eddies (Thompson et al., 2003; Yamada & Pauluis, 2015) and the supply of water vapor to the poleward moist component of the warm branch.…”

“…The total column air mass, which is proportional to the surface pressure, shows positive (negative) anomalies in the high (mid-) latitudes associated with WB_D + events (Figure 4c), suggesting a negative phase of the Arctic Oscillation. A negative Arctic Oscillation is well known to be accompanied by stronger planetary wave activity, favoring the stronger southward transport of cold air (Chen et al, 2005;Yu et al, 2015b;H. Gong et al, 2019aH.…”