Impact of internal variability on recent opposite trends in wintertime temperature over the Barents–Kara Seas and central Eurasia

Abstract

The large ensembles of the IPSL-CM6A-LR model output for the historical forcing experiment were employed to investigate the role of internal variability in the formation of the recent "warm Arctic-cold Eurasia" trend pattern in winter surface air temperature (SAT). In the simulations, the winter SAT trends during 1991-2014 display remarkable inter-member diversity over the Barents-Kara Seas region and central Eurasia, suggesting an important role played by internal variability. It is indicated that internally generated SAT trends over the Barents-Kara Seas are induced mainly by the change in local sea surface temperature (SST) trends. Furthermore, we nd that the warming trend over the Barents-Kara Seas can induce an anomalous anticyclone over northern Eurasia, which in turn can contribute positively to the warming anomalies over the Barens-Kara Seas, but cannot account for the cooling trend over central Eurasia. The cooling trend over central Eurasia can be attributed to the negative Arctic Oscillation (AO)like atmospheric circulation pattern, which is independent of the climate change over the Arctic. Therefore, the observed opposite winter SAT trends over the Barents-Kara Seas and central Eurasia arise partly from the linear combination of high SST trends over the Barents-Kara Seas and decline in the winter AO index.

Quantifying Contributions of External Forcing and Internal Variability to Arctic Warming During 1900–2021

“…Rapid Arctic warming is a robust feature of the ongoing climate change, with significant impacts on Arctic ecosystems and climate. Arctic warming rate is not homogeneous over time, with decadal‐to‐multidecadal variations that modulate the long‐term warming trend (e.g., Bokuchava & Semenov, 2021; Chylek et al., 2014; England et al., 2021; Johannessen et al., 2004; Serreze & Barry, 2011; Serreze & Francis, 2006) and affect midlatitude climate (Dai & Deng, 2022; Wang & Chen, 2021). In general, the Arctic experienced accelerated warming in the early 20th century before the 1940s and in the recent decades since the 1980s, but between them the warming is relatively slow (e.g., Bokuchava & Semenov, 2021; England, 2021; Serreze & Barry, 2011; Svendsen et al., 2021).…”

Interannual variation of the Warm Arctic–Cold Eurasia pattern modulated by Ural blocking and the North Atlantic Oscillation under changing sea ice conditions

“…This pattern with two distinct winter temperature anomalies centered over the BKS and CEU is known as the Warm Arctic-Cold Eurasia (WACE) pattern, which is characterized as the second leading mode of winter surface air temperature (SAT) over Eurasia (Mori et al 2014). Despite the dedicated research effort in recent years on the causes of both the frequent cold winters in Eurasia and the WACE pattern, the mechanism linking the Arctic and the mid-latitude winter climate remains to be fully elucidated (e.g., Inoue et al 2012;McCusker et al 2016;Sun et al 2016;Zhang et al Page 2 of 12 Zhou et al Progress in Earth and Planetary Science (2023) 10:59 2018; Blackport et al 2019;He et al 2020;Wang and Chen 2022). It has been proposed that sea ice decline over the BKS has influenced the recent cold winters in Eurasia (e.g., Inoue et al 2012;Mori et al 2019), and that modulation of cyclone tracks and the troposphere-stratosphere pathway is responsible for the remote effect of sea ice loss (Inoue et al 2012;Kim et al 2014;Nakamura et al 2015;Zhang et al 2018).…”