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Katharine S. Law
,
Andreas Stohl
,
Patricia K. Quinn
,
Charles A. Brock
,
John F. Burkhart
,
Jean-Daniel Paris
,
Gerard Ancellet
,
Hanwant B. Singh
,
Anke Roiger
,
Hans Schlager
,
Jack Dibb
,
Daniel J. Jacob
,
Steve R. Arnold
,
Jacques Pelon
, and
Jennie L. Thomas

Given the rapid nature of climate change occurring in the Arctic and the difficulty climate models have in quantitatively reproducing observed changes such as sea ice loss, it is important to improve understanding of the processes leading to climate change in this region, including the role of short-lived climate pollutants such as aerosols and ozone. It has long been known that pollution produced from emissions at midlatitudes can be transported to the Arctic, resulting in a winter/spring aerosol maximum known as Arctic haze. However, many uncertainties remain about the composition and origin of Arctic pollution throughout the troposphere; for example, many climate–chemistry models fail to reproduce the strong seasonality of aerosol abundance observed at Arctic surface sites, the origin and deposition mechanisms of black carbon (soot) particles that darken the snow and ice surface in the Arctic is poorly understood, and chemical processes controlling the abundance of tropospheric ozone are not well quantified. The International Polar Year (IPY) Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, Climate, Chemistry, Aerosols and Transport (POLARCAT) core project had the goal to improve understanding about the origins of pollutants transported to the Arctic; to detail the chemical composition, optical properties, and climate forcing potential of Arctic aerosols; to evaluate the processes governing tropospheric ozone; and to quantify the role of boreal forest fires. This article provides a review of the many results now available based on analysis of data collected during the POLARCAT aircraft-, ship-, and ground-based field campaigns in spring and summer 2008. Major findings are highlighted and areas requiring further investigation are discussed.

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Taneil Uttal
,
Sandra Starkweather
,
James R. Drummond
,
Timo Vihma
,
Alexander P. Makshtas
,
Lisa S. Darby
,
John F. Burkhart
,
Christopher J. Cox
,
Lauren N. Schmeisser
,
Thomas Haiden
,
Marion Maturilli
,
Matthew D. Shupe
,
Gijs De Boer
,
Auromeet Saha
,
Andrey A. Grachev
,
Sara M. Crepinsek
,
Lori Bruhwiler
,
Barry Goodison
,
Bruce McArthur
,
Von P. Walden
,
Edward J. Dlugokencky
,
P. Ola G. Persson
,
Glen Lesins
,
Tuomas Laurila
,
John A. Ogren
,
Robert Stone
,
Charles N. Long
,
Sangeeta Sharma
,
Andreas Massling
,
David D. Turner
,
Diane M. Stanitski
,
Eija Asmi
,
Mika Aurela
,
Henrik Skov
,
Konstantinos Eleftheriadis
,
Aki Virkkula
,
Andrew Platt
,
Eirik J. Førland
,
Yoshihiro Iijima
,
Ingeborg E. Nielsen
,
Michael H. Bergin
,
Lauren Candlish
,
Nikita S. Zimov
,
Sergey A. Zimov
,
Norman T. O’Neill
,
Pierre F. Fogal
,
Rigel Kivi
,
Elena A. Konopleva-Akish
,
Johannes Verlinde
,
Vasily Y. Kustov
,
Brian Vasel
,
Viktor M. Ivakhov
,
Yrjö Viisanen
, and
Janet M. Intrieri

Abstract

International Arctic Systems for Observing the Atmosphere (IASOA) activities and partnerships were initiated as a part of the 2007–09 International Polar Year (IPY) and are expected to continue for many decades as a legacy program. The IASOA focus is on coordinating intensive measurements of the Arctic atmosphere collected in the United States, Canada, Russia, Norway, Finland, and Greenland to create synthesis science that leads to an understanding of why and not just how the Arctic atmosphere is evolving. The IASOA premise is that there are limitations with Arctic modeling and satellite observations that can only be addressed with boots-on-the-ground, in situ observations and that the potential of combining individual station and network measurements into an integrated observing system is tremendous. The IASOA vision is that by further integrating with other network observing programs focusing on hydrology, glaciology, oceanography, terrestrial, and biological systems it will be possible to understand the mechanisms of the entire Arctic system, perhaps well enough for humans to mitigate undesirable variations and adapt to inevitable change.

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