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Airmass Origin in the Arctic. Part I: Seasonality

Orbe, Clara; Newman, Paul A.; Waugh, Darryn W.; Holzer, Markus; Oman, Luke D.; Li, Feng; Polvani, Lorenzo M.

The first climatology of airmass origin in the Arctic is presented in terms of rigorously defined airmass fractions that partition air according to where it last contacted the planetary boundary layer (PBL). Results from a present-day climate integration of the Goddard Earth Observing System Chemistry–Climate Model (GEOSCCM) reveal that the majority of air in the Arctic below 700 mb last contacted the PBL poleward of 60°N. By comparison, 62% (±0.8%) of the air above 700 mb originates over Northern Hemisphere midlatitudes (i.e., “midlatitude air”). Seasonal variations in the airmass fractions above 700 mb reveal that during boreal winter air from midlatitudes originates primarily over the oceans, with 26% (±1.9%) last contacting the PBL over the eastern Pacific, 21% (±0.87%) over the Atlantic, and 16% (±1.2%) over the western Pacific. During summer, by comparison, midlatitude air originates primarily over land, overwhelmingly so over Asia [41% (±1.0%)] and, to a lesser extent, over North America [24% (±1.5%)]. Seasonal variations in the airmass fractions are interpreted in terms of changes in the large-scale ventilation of the midlatitude boundary layer and the midlatitude tropospheric jet.

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Title
Journal of Climate
DOI
https://doi.org/10.1175/JCLI-D-14-00720.1

More About This Work

Academic Units
Lamont-Doherty Earth Observatory
Earth and Environmental Sciences
Applied Physics and Applied Mathematics
Publisher
American Meteorological Society
Published Here
February 24, 2016
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