Air-mass Origin in the Arctic. Part II: Response to Increases in Greenhouse Gases ...

• Main Authors: ORBE, CLARA, EWMAN, PAUL A., WAUGH, DARRYN W., HOLZER, MARK, OMAN, LUKE D., LI, FENG, POLVANI, LORENZO M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: AMS 2015
• Subjects: Arctic
• Online Access: https://dx.doi.org/10.13016/m2jqep-kp3u; https://mdsoar.org/handle/11603/26726

Future changes in transport from Northern Hemisphere (NH) midlatitudes into the Arctic are examined using rigorously defined air-mass fractions that partition air in the Arctic according to where it last had contact with the planetary boundary layer (PBL). Boreal winter (December–February) and summer (June–August) air-mass fraction climatologies are calculated for the modeled climate of the Goddard Earth Observing System Chemistry–Climate Model (GEOSCCM) forced with the end-of-twenty-first century greenhouse gases and ozone-depleting substances. The modeled projections indicate that the fraction of air in the Arctic that last contacted the PBL over NH midlatitudes (or air of ‘‘midlatitude origin’’) will increase by about 10% in both winter and summer. The projected increases during winter are largest in the upper and middle Arctic troposphere, where they reflect an upward and poleward shift in the transient eddy meridional wind, a robust dynamical response among comprehensive climate models. The boreal ...