Interdecadal variability of the warm Arctic-cold Eurasia pattern linked to the Barents oscillation

Artikel i vetenskaplig tidskrift, 2023

Observed winter near-surface air temperature anomalies in the Northern Hemisphere have exhibited a warm Arctic-cold Eurasia (WACE) pattern with interdecadal variation in recent decades, but the exact mechanism behind WACE is still under debate. This study used reanalysis data and climate model simulations to investigate the interdecadal variability of the WACE pattern on a centennial scale, as well as the role of atmospheric circulations. It is found that the second mode of atmospheric variability over the North Atlantic-Arctic region, known as the Barents oscillation (BO), played a dominant role in regulating the interdecadal variability of WACE. The atmospheric circulation associated with the positive phase of the BO corresponds to an anomalous enhancement of the quasi-barotropic anticyclone near the southern Barents-Kara Seas (BKS) and the North Atlantic, as well as a weakening of the mid-latitude westerly jet. This atmospheric circulation anomaly favors the northward transport of atmospheric heat and moisture to the BKS from the mid-latitudes, resulting in an increased air temperature through downward longwave radiation. Concurrently cold air is transported from the polar region to Central Eurasia (CE), decreasing air temperature over CE. The amplified temperature anomaly dipole results in the decadal enhancement of the WACE pattern. The atmospheric circulation anomalies related to the negative phase of the BO are the opposite, which in turn leads to the decadal weakening of the WACE pattern. Our results further support the important role of internal atmospheric variability in the formation of WACE and emphasize that the atmospheric circulation associated with the BO is the main driver of WACE decadal variability over the past century.