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

The present study investigated the joint impacts of the spring Arctic Oscillation (AO) and the Scandinavia (SCAND) teleconnection pattern on spring surface air temperature (SAT) variations over the midhigh latitude Eurasia. It is found that the connection of the spring AO (SCAND) to the first two empirical orthogonal function (EOF) modes of the spring Eurasian SAT variations depends strongly on the phase of the spring SCAND (AO) index. The EOF1 and EOF2 modes display same sign variation and tripole pattern, respectively. In the in-phase AO-SCAND years, the mid-high latitude Eurasia is covered by same sign SAT anomalies, and the spring AO and SCAND indices both have a strong (weak) connection with the EOF1 (EOF2) mode. In the out-of-phase AO-SCAND years, the SAT anomalies over the mid-high latitude Eurasia are featured by a tripole pattern, and the connection of the spring AO and SCAND indices with the EOF1 (EOF2) is insignificant (significant). Differences in the distribution of SAT anomalies between the in-phase and out-of-phase AO-SCAND years are attributed to the constructive and destructive superposition of atmospheric circulation anomalies related to the spring AO and SCAND indices. The observed joint impacts of the spring AO and SCAND on spring Eurasian SAT variations are captured by a historical simulation of the flexible global ocean-atmosphere-land system model, spectral version 2. Analysis indicates that the prediction skill of the spring Eurasian SAT variations related to the first two EOF modes is enhanced when taking both the spring AO and SCAND signals into account.