Airmass Origin in the Arctic. Part I: Seasonality
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Author/Creator ORCID
Date
2015-06-15
Type of Work
Department
Program
Citation of Original Publication
Orbe, C., Newman, P. A., Waugh, D. W., Holzer, M., Oman, L. D., Li, F., & Polvani, L. M. (2015). Airmass Origin in the Arctic. Part I: Seasonality, Journal of Climate, 28(12), 4997-5014. Retrieved Jan 10, 2023, from https://journals.ametsoc.org/view/journals/clim/28/12/jcli-d-14-00720.1.xml
Rights
This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Public Domain Mark 1.0
Public Domain Mark 1.0
Subjects
Abstract
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
608N. 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.