Atmospheric Pressure Rivalry Between the Arctic and Northern Pacific: Implications for Alaskan Climate Variability

• Published in: International journal of climatology 2024-12, Vol.44 (15), p.5339-5357
• Main Authors: Polyakov, Igor V., Ballinger, Thomas J., Overland, James E., Vavrus, Stephen J., Danielson, Seth L., Lader, Rick, Bhatt, Uma S., Hendricks, Amy S., Mueter, Franz J.
• Format: Article
• Language: English
• Subjects: Aleutian low; Arctic climates; Arctic fronts; Arctic zone; Atmospheric pressure; Atmospheric processes; Biota; Climate change; Climate system; Climate variability; Confluence; Freshwater; Ice cover; Ice environments; Inland water environment; Ocean basins; Pacific Arctic; Pressure distribution; Pressure effects; Regional climates; Sea ice; Sea level pressure; sea level pressure patterns; Variability; Water masses; Water transport; Winds
• ISSN: 0899-8418; 1097-0088
• DOI: 10.1002/joc.8638

ABSTRACT Located at the confluence of the Arctic and North Pacific and with Alaska at its heart, the Pacific Arctic Region (PAR) is a unique and interconnected regional climate system. Significant climatic changes in the PAR are described by a novel, mobile monthly Alaska Arctic Front (AAF) index, which is defined by sea level pressure differences between the migratory cores of the Beaufort High and Aleutian Low. Regional climate variability associated with the AAF shows prominent decadal signatures that are driven by the opposing effects of the North Pacific and the Arctic atmospheric pressure fields. Low AAF (negative phase) is dominated by North Pacific forcing, whereas high AAF (positive phase) is dominated by Arctic atmospheric processes. The recent (2011–2021) negative AAF phase, which is associated with the westward displacement of Aleutian Low explaining stronger northward winds and enhanced water transport northward through Bering Strait, is conducive to increased oceanic heat and freshwater content, reduced regional sea ice cover in the PAR, and to the expansion of Pacific species into the Arctic. These factors are all indicators of the Pacification of the Arctic Ocean, a key feature of climate change related to progression of anomalous Pacific water masses and biota into the polar basins. It is not yet clear if or when the recent phase of decadal variability will change and alter the rate of Pacification of the Arctic climate system. The recent phase of decadal mode of variability in the Pacific Arctic Region is dominated by the North Pacific Aleutian Low and is associated with the Pacification of the Arctic Ocean, with conditions favourable for regional warming, freshening, and expansion of Pacific species into the Arctic.