Arctic sea ice melt onset favored by an atmospheric pressure pattern reminiscent of the North American-Eurasian Arctic pattern

• Published in: Climate dynamics Vol. 57; no. 7-8; pp. 1771 - 1787
• Main Authors: Horvath, Sean, Stroeve, Julienne, Rajagopalan, Balaji, Jahn, Alexandra
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2021; Springer; Springer Nature B.V
• Subjects: Archipelagoes; Arctic sea ice; Atmospheric moisture; Atmospheric pressure; Catalysts; Circulation patterns; Climatology; Dipoles; Downwelling; Earth and Environmental Science; Earth Sciences; Environmental aspects; Funnels; Geophysics/Geodesy; High pressure; Ice melting; Long wave radiation; Low pressure; Melting points; Moisture; Oceanography; Pressure patterns; Radiation; Sea ice; Sea level; Sea level pressure; Self organizing maps; Transport; Arctic; North America; Arctic region; Arctic sea ice; Melt onset; Atmospheric moisture transport; Atmospheric circulation; Climate variability; Self organizing maps (SOM)
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-021-05776-y

The timing of melt onset in the Arctic plays a key role in the evolution of sea ice throughout Spring, Summer and Autumn. A major catalyst of early melt onset is increased downwelling longwave radiation, associated with increased levels of moisture in the atmosphere. Determining the atmospheric moisture pathways that are tied to increased downwelling longwave radiation and melt onset is therefore of keen interest. We employed Self Organizing Maps (SOM) on the daily sea level pressure for the period 1979–2018 over the Arctic during the melt season (April–July) and identified distinct circulation patterns. Melt onset dates were mapped on to these SOM patterns. The dominant moisture transport to much of the Arctic is enabled by a broad low pressure region stretching over Siberia and a high pressure over northern North America and Greenland. This configuration, which is reminiscent of the North American-Eurasian Arctic dipole pattern, funnels moisture from lower latitudes and through the Bering and Chukchi Seas. Other leading patterns are variations of this which transport moisture from North America and the Atlantic to the Central Arctic and Canadian Arctic Archipelago. Our analysis further indicates that most of the early and late melt onset timings in the Arctic are strongly related to the strong and weak emergence of these preferred circulation patterns, respectively.