Abstract
In this study, the effects of the Northern Hemisphere atmospheric blocking circulation on Arctic sea ice decline at weekly time scales are examined by defining four key regions based on observational data analysis. Given the regression analysis, the frequently occurring atmospheric patterns related to the sea ice decline in four key sea regions (Baffin Bay, Barents-Kara Seas, Okhotsk Sea and Bering Sea) are found to be Greenland blocking (GB), Ural blocking (UB), western Pacific blocking (PB-W) and eastern Pacific blocking (PB-E), respectively. The results show that the regional blocking frequency is higher (lower) in lower (higher) sea ice winters for each key region. Moreover, composite analysis indicates that blocking evolution is usually accompanied by significant sea ice decline at weekly time scales during the blocking life cycle for each key region. In addition, the intensified surface downward infrared radiation (IR) anomaly and the precipitable water for the entire atmosphere (PWA) in each key region are found to make significant contributions to the positive surface air temperature (SAT) anomaly, which is beneficial for the reduction in sea ice. The approximate quantitative analysis of different surface energy fluxes induced by blocking is also applied. Further analysis shows that the blocking event and the associated changes in SAT and radiation anomalies for each key region lead the sea ice decline by approximately 3~6 days. This result indicates that regional blocking can contribute to regional sea ice decline at weekly time scales through surface warming associated with enhanced water vapor and associated IR variations. Further quantitative estimates indicate that regional blocking can reduce regional sea ice cover (SIC) by 49.6%, 49.4%, 52.2% and 49.5% for Baffin Bay, Barents-Kara Seas, Okhotsk Sea and Bering Sea, respectively, during the blocking life cycle. Finally, a physical process diagrammatic sketch is given to illustrate how blocking affects SIC decline.
Highlights
The Arctic amplification has attracted many researchers in recent decades [1,2,3,4] and the direct effect of the Arctic amplification is Arctic warming and the rapid melting of Arctic sea ice in all seasons [5,6]
Radiation anomalies for each key region lead the sea ice decline by approximately 3~6 days. This result indicates that regional blocking can contribute to regional sea ice decline at weekly time scales through surface warming associated with enhanced water vapor and associated infrared radiation (IR) variations
In this study, we do not intend to focus on the interdecadal linear trend in Arctic sea ice but rather on the possible link between the sea ice variabilities in each key region and the regional atmospheric circulation, especially at the weekly time scale
Summary
The Arctic amplification has attracted many researchers in recent decades [1,2,3,4] and the direct effect of the Arctic amplification is Arctic warming and the rapid melting of Arctic sea ice in all seasons [5,6]. For different key sea regions, as shown, the role of regional blocking in the regional SIC decline is unclear and needs to be further clarified. At weekly time scales especially, the physical processes by which regional blocking affects SIC variation still need to be addressed. The goals of this study are to examine how the regional blocking circulations affect the regional SIC declines at weekly time scales and to determine the physical. SIC across whole that the atmospheric circulations (blockings) make important contributions to the SIC decline [7,19,20], Arctic from 1979–2016, four key sea regions of SIC change are chosen. Section regional SIC declines at weekly time scales and to determine the physical processes involved. Represent values that are above the 95% confidence level based on a two-sided Student’s t test
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
