Role of Ural blocking in Arctic sea ice loss and its connection with Arctic warming in winter
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Role of Ural blocking in Arctic sea ice loss and its connection with Arctic warming in winter Dong‑Jae Cho1 · Kwang‑Yul Kim1 Received: 13 July 2020 / Accepted: 17 November 2020 © The Author(s) 2020
Abstract Ural blocking (UB) is suggested as one of the contributors to winter sea ice loss in the Barents–Kara Seas (BKS). This study compares UB with Arctic warming (AW) in order to delineate the role of UB on winter sea ice loss and its potential link with AW. A detailed comparison reveals that UB and AW are partly linked on sub-seasonal scales via a two-way interaction; circulation produced by AW affects UB and advection induced by UB affects temperature in AW. On the other hand, the long-term impacts of AW and UB on the sea ice concentration in the BKS are distinct. In AW, strong turbulent flux from the sea surface warms the lower troposphere, increases downward longwave radiation, and broadens the open sea surface. This feedback process explains the substantial sea ice reduction observed in the BKS in association with long-term accelerating trend. Patterns of turbulent flux, net evaporation, and net longwave radiation at surface associated with UB are of opposite signs to those associated with AW, which implies that moisture and heat flux is suppressed as warm and moist air is advected from mid-latitudes. As a result, vertical feedback process is hindered under UB. The qualitative and quantitative differences arise in terms of their impacts on sea ice concentrations in the BKS, because strong turbulent flux from the open sea surface is a main driving force in AW whereas heat and moisture advection is a main forcing in UB. Keywords Sea ice concentration · Ural blocking · Arctic warming · Feedback mechanism · Heat and moisture budget analysis
1 Introduction Growing concerns over the recent changes of rapid sea ice loss and atmospheric warming in the Arctic, known as Arctic warming (AW), have led to major debates on its linkage to mid-latitude weather in winter (Cohen et al. 2020). A number of studies suggested a connection between AW and harsh mid-latitude winters, which is often referred as “warm Arctic–cold Eurasia (WACE)” (Overland et al. 2011; Francis and Vavrus 2012; Mori et al. 2014; Kug et al. 2015). Meanwhile, other studies report that recent WACE is associated with natural variability rather than AW (Singarayer
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00382-020-05545-3) contains supplementary material, which is available to authorized users. * Kwang‑Yul Kim [email protected] 1
School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
et al. 2005; Barnes 2013; Blackport and Screen 2020; Dai and Song 2020). Screen (2017) showed that atmospheric response to a regional forcing (sea ice reduction) resembles the WACE pattern, although an ensemble of model simulations with a pan-Arctic forcing did not yield mid-latitude cooling. This shows that observational and modeling studies are in accord only on a reg
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