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Darin Toohey
,
John McConnell
,
Linnea Avallone
, and
Wayne Evans

Aircraft emissions impact the atmosphere in a variety of ways, including enhancing greenhouse gases, especially water vapor and carbon dioxide, in the upper troposphere and lower stratosphere, forming persistent contrails, and altering the distributions of reactive chemical species, which change the oxidative capacity of the atmosphere. This paper summarizes some recent findings related to the impacts of aircraft exhaust on the chemistry of the upper troposphere and lower stratosphere (UTLS). Of particular note are the improvements in our understanding of production of nitrogen oxides (NOx ~ NO + NO2) by lightning and of the influence of long-range transport on background abundances of reactive species. Studies have also identified gaps in our knowledge, including the behavior of HOx (OH and HO2) species at high NOx and discrepancies in measurements of water vapor in the relatively dry UTLS. Lack of detailed observations of species, such as the halogens chlorine and bromine, limits our ability to assess the role of heterogeneous chemistry on UTLS chemistry with or without the influence of aircraft exhaust. Recommendations for studies that address these issues are presented.

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Florence Rabier
,
Aurélie Bouchard
,
Eric Brun
,
Alexis Doerenbecher
,
Stéphanie Guedj
,
Vincent Guidard
,
Fatima Karbou
,
Vincent-Henri Peuch
,
Laaziz El Amraoui
,
Dominique Puech
,
Christophe Genthon
,
Ghislain Picard
,
Michael Town
,
Albert Hertzog
,
François Vial
,
Philippe Cocquerez
,
Stephen A. Cohn
,
Terry Hock
,
Jack Fox
,
Hal Cole
,
David Parsons
,
Jordan Powers
,
Keith Romberg
,
Joseph VanAndel
,
Terry Deshler
,
Jennifer Mercer
,
Jennifer S. Haase
,
Linnea Avallone
,
Lars Kalnajs
,
C. Roberto Mechoso
,
Andrew Tangborn
,
Andrea Pellegrini
,
Yves Frenot
,
Jean-Noël Thépaut
,
Anthony McNally
,
Gianpaolo Balsamo
, and
Peter Steinle

The Concordiasi project is making innovative observations of the atmosphere above Antarctica. The most important goals of the Concordiasi are as follows:

  • To enhance the accuracy of weather prediction and climate records in Antarctica through the assimilation of in situ and satellite data, with an emphasis on data provided by hyperspectral infrared sounders. The focus is on clouds, precipitation, and the mass budget of the ice sheets. The improvements in dynamical model analyses and forecasts will be used in chemical-transport models that describe the links between the polar vortex dynamics and ozone depletion, and to advance the under understanding of the Earth system by examining the interactions between Antarctica and lower latitudes.

  • To improve our understanding of microphysical and dynamical processes controlling the polar ozone, by providing the first quasi-Lagrangian observations of stratospheric ozone and particles, in addition to an improved characterization of the 3D polar vortex dynamics. Techniques for assimilating these Lagrangian observations are being developed.

A major Concordiasi component is a field experiment during the austral springs of 2008–10. The field activities in 2010 are based on a constellation of up to 18 long-duration stratospheric super-pressure balloons (SPBs) deployed from the McMurdo station. Six of these balloons will carry GPS receivers and in situ instruments measuring temperature, pressure, ozone, and particles. Twelve of the balloons will release dropsondes on demand for measuring atmospheric parameters. Lastly, radiosounding measurements are collected at various sites, including the Concordia station.

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