The IAGOS team in Toulouse is very happy to welcome 2 new collaborators :

- Audrey GAUDEL is the new collaborator for the MACC-II program, on the VAL sub-project.

On the supervision of Valérie Thouret and Hannah Clark, she is responsible of the automatic validation of the models with IAGOS data.

Visit the dedicated web site: http://www.iagos.fr/macc

Contact: audrey.gaudel@aero.obs-mip.fr

- Benoît GAUTRON is the new collaborator for the IGAS project. On the supervison of Valérie Thouret and Damien Boulanger, he is responsible of the further development of the IAGOS central database including metadata and interoperability.

Visit the web site project: http://www.igas-project.org

Contact: benoit.gautron@aero.obs-mip.fr

P. G. Hess and R. Zbinden, Stratospheric impact on tropospheric ozone variability and trends: 1990–2009, Atmos. Chem. Phys., 13, 649–674, 2013.

The influence of stratospheric ozone on the interannual variability and trends in tropospheric ozone is evaluated between 30 and 90◦ N from 1990–2009 using ozone measurements and a global chemical transport model, the Community Atmospheric Model with chemistry (CAM-chem). Long-term measurements from ozonesondes, at 150 and 500 hPa, and the Measurements of OZone and water vapour by in-service Airbus aircraft programme (MOZAIC), at 500 hPa, are analyzed over Japan, Canada, the Eastern US and Northern and Central Europe. The measurements generally emphasize northern latitudes, although the simulation suggests that measurements over the Canadian, Northern and Central European regions are representative of the large-scale interannual ozone variability from 30 to 90◦ N at 500 hPa. CAM-chem is run with input meteorology from the National Center for Environmental Prediction; a tagging methodology is used to identify the stratospheric contribution to tropospheric ozone concentrations. A variant of the synthetic ozone tracer (synoz) is used to represent stratospheric ozone. Both the model and measurements indicate that on large spatial scales stratospheric interannual ozone variability drives significant tropospheric variability at 500 hPa and the surface (Fig 5 below). In particular, the simulation and the measurements suggest large stratospheric influence at the surface sites of Mace Head (Ireland) and Jungfraujoch (Switzerland) as well as many 500 hPa measurement locations. Both the measurements and simulation suggest the stratosphere has contributed to tropospheric ozone trends. In many locations between 30–90◦ N 500 hPa ozone significantly increased from 1990–2000, but has leveled off since (from 2000–2009). The simulated global ozone budget suggests global stratosphere-troposphere exchange increased in 1998–1999 in association with a global ozone anomaly. Discrepancies between the simulated and measured ozone budget include a large underestimation of measured ozone variability and discrepancies in long-term stratospheric ozone trends. This suggests the need for more sophisticated simulations including better representations of stratospheric chemistry and circulation.

In Figure a, the differences in the tropospheric burden of ozone (O3, solid black), of stratospheric ozone (O3s, dotted black), tropospheric chemical ozone (O3NOX, blue) and synoz* (representative of STE, green) are given from their 1990 annually averaged burden (354 Tg, 190 Tg, 164 Tg and 253 Tg, respectively).

In Figure b, the change in net STE (blue lines), net chemistry (red) and surface deposition (green) compared to 1990 is given for both O3 (solid lines) and O3S (dotted lines).

January 2013 is the first month the new IGAS project.

IGAS stands for IAGOS for the GMES Atmospheric Service (although GMES has recently been renamed "Copernicus").

Please visit the following web site for further details :

http://www.igas-project.org/