Impact of Greenland blocking on midlatitude extreme cold weather: Modulation of Arctic sea ice in western Greenland

• Published in: Science China. Earth sciences Vol. 64; no. 7; pp. 1065 - 1079
• Main Authors: Chen, Xiaodan, Luo, Dehai
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.07.2021; Springer Nature B.V
• Subjects: Anomalies; Arctic sea ice; Atmospheric circulation; Brittleness; Cold; Cold surges; Cold weather; Dispersion; Earth and Environmental Science; Earth Sciences; Extreme cold; Extreme low temperatures; Extreme weather; Ice; Modulation; Nonlinear systems; Nonlinearity; Phase velocity; Polar environments; Potential vorticity; Research Paper; Sea ice; Surface temperature; Vorticity; Wind; Winter; Winter circulation; Zonal winds; Arctic region; Greenland; Arctic sea ice; Greenland blocking; Meridional gradient of potential vorticity; Extreme cold weather
• ISSN: 1674-7313; 1869-1897
• DOI: 10.1007/s11430-020-9782-2

In this study, we analyzed 1979–2019 daily ERA-Interim reanalysis data in winter and performed atmospheric circulation experiments to examine the modulation of Arctic sea ice in western Greenland (Baffin Bay, Davis Strait, and the Labrador Sea, BDL) on winter Greenland blockings. It is found that low BDL sea ice and high BDL surface temperature favor frequent, long-lived, westward-moving Greenland blockings in winter, which cause frequent and strengthening cold surges over the mid-eastern United States. In contrast, high BDL sea ice and low BDL surface temperature favor short-lived, less frequent and quasi-stationary Greenland blockings, mainly leading to cold anomalies in North Europe. Low wintertime BDL sea ice reduces the background potential vorticity meridional gradient (PV y ) and zonal wind over the mid-high latitudes of the North Atlantic, which enhances the nonlinearity of Greenland blocking, accelerates the phase speed of its westward movement, and weakens its energy dispersion, thus favoring the occurrence and persistence of Greenland blocking. High BDL sea ice strengthens the background PV y and zonal wind in the mid-high latitudes of the North Atlantic, which weakens the nonlinearity and movement of Greenland blocking, enhances its energy dispersion, and thus suppresses the occurrence and persistence of Greenland blocking and its retrogression. A set of atmospheric circulation experiments supports the above results based on the reanalysis dataset.