Dominant Modes of Interannual Variability in Eurasian Surface Air Temperature during Boreal Spring

Abstract

This study investigates interannual variations of surface air temperature (SAT) over mid-and high latitudes of Eurasia during boreal spring and their association with snow, atmospheric circulation, and sea surface temperature (SST) changes. The leading mode of spring SAT variations is featured by same-sign anomalies over most regions. The second mode features a tripole anomaly pattern with anomalies over the central part opposite to those over the eastern and western parts of Eurasia. A diagnosis of surface heat flux anomalies suggests that snow change contributes partly to SAT anomalies in several regions mainly by modulating surface shortwave radiation but cannot explain SAT changes in other regions. Atmospheric circulation anomalies play an important role in spring SAT variability via wind-induced heat advection and cloud-induced surface radiation changes. Positive SAT anomalies are associated with anomalous westerly winds from the North Atlantic Ocean or with anomalous anticyclone and southerly winds. Negative SAT anomalies occur in regions of anomalous cyclone and northerly winds. Atmospheric circulation anomalies associated with the first mode have a close relationship to spring Arctic Oscillation (AO), indicating the impact of the AO on continental-scale spring SAT variations over the mid-and high latitudes of Eurasia. The atmospheric circulation anomalies associated with the second mode feature a wave pattern over the North Atlantic and Eurasia. Such a wave pattern is related to a tripole SST anomaly pattern in the North Atlantic Ocean, signifying the contribution of the North Atlantic Ocean state to the formation of a tripole SAT anomaly pattern over the mid-and high latitudes of Eurasia.

Seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring and the associated surface heat budget

“…However, the relationship between the dominant modes of Eurasian snow and atmospheric circulation during autumn and spring is still not clear. In addition, a better understanding of the snow-atmosphere coupling mode demands a deeper insight into the associated boundary thermal conditions (Chen, Wu, and Liu 2016).…”

“…Excessive autumn and winter Eurasian snow cover can cause a negative-phase winter AO mode, and vice versa (Saito, Cohen, and Entekhabi 2001;Cohen et al 2007). On the other hand, the AO/NAO mode also exerts important influence on the Eurasian snowpack variability as the Eurasian continent is warmer in the positive-phase AO (Clark, Serreze, and Robinson 1999;Kim, Kim, and Kim 2013;Chen, Wu, and Liu 2016). A consensus has been reached that the Eurasian snow cover variability is more dependent on temperature than on precipitation (Walland and Simmonds 1997;Henderson and Leathers 2010;Yeo, Kim, and Kim 2017).…”

Combined Influence of the Arctic Oscillation and the Scandinavia Pattern on Spring Surface Air Temperature Variations Over Eurasia

“…SAT variations over Eurasia were impacted by lower boundary factors, including Eurasian snow cover (Chen et al, ; K. Ye et al, ), the Arctic sea ice (Chen & Wu, ; J. P. Liu et al, , C. Sun et al, ; J. Zuo et al, ), and sea surface temperature (SST) in the North Atlantic and Pacific (Chen et al, , ; Graf & Zanchettin, ; R. Wu & Chen, ; R. Wu et al, , ). Above mentioned studies generally showed that atmospheric circulation anomalies play an important role in relaying the impacts of the Arctic sea ice and SST on the Eurasian SAT.…”

“…Above mentioned studies generally showed that atmospheric circulation anomalies play an important role in relaying the impacts of the Arctic sea ice and SST on the Eurasian SAT. R. Wu et al () and Chen et al () indicated that the North Atlantic SST anomalies influence the Eurasian SAT variations via triggering an atmospheric wave train over the North Atlantic through the Eurasia. J. Zuo et al () reported that preceding autumn Arctic sea ice anomalies have a significant influence on the subsequent winter temperature variations over China via modulating the Siberian High and the East Asian trough.…”

“…They showed that pronounced positive (negative) SAT anomalies appear over most parts of Eurasia during positive (negative) phase of spring AO. Spring AO affects Eurasian SAT variations primarily through wind‐induced horizontal temperature advection and cloud‐induced surface shortwave radiation change (Chen et al, ).…”