Atmos. Chem. Phys. Discuss., 7, 2389-2475, 2007
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
An overview of the HIBISCUS campaign
J.-P. Pommereau1, A. Garnier1, G. Held2, A.-M. Gomes2, F. Goutail1, G. Durry1,*, F. Borchi1, A. Hauchecorne1, N. Montoux1, P. Cocquerez3, G. Letrenne3, F. Vial4, A. Hertzog5, B. Legras4, I. Pisso4, J. A. Pyle5, N. R. P. Harris5, R. L. Jones5, A. Robinson5, G. Hansford5, L. Eden5, T. Gardiner6, N. Swann6, B. Knudsen7, N. Larsen7, J. Nielsen7, T. Christensen7, F. Cairo8, M. Pirre9, V. Marécal9, N. Huret9, E. Riviére9,*, H. Coe10, D. Grosvenor10, K. Edvarsen11, G. Di Donfrancesco12, P. Ricaud13, J.-J. Berthelier14, M. Godefroy14, E. Seran14, K. Longo15, and S. Freitas15
1CNRS-Service d'Aéronomie, Verrières le Buisson, France
2Instituto de Pesquisas Meteorológicas, UNESP, Bauru, Brazil
3Centre National d’Etudes Spatiales, Toulouse, France
4CNRS-Laboratoire de Météorologie Dynamique, Palaiseau, France
5University of Cambridge, Dept of Chemistry, Cambridge, UK
6National Physical Laboratory, Teddington, UK
7Danish Meteorological Institute, Copenhagen, Denmark
8CNR-Institute for Atmospheric Science and Climate, Roma, Italy
9CNRS-Laboratoire de Physique et Chime de l’Environment, Orléans, France
10University of Manchester Institute of Science and Technology, Manchester, UK
11Norwegian Institute for Air Research, Kjeller, Norway
12ENEA, Ente Per le Nuevo Tecnologie, l’Energia, l’Ambiante, Roma, Italy
13CNRS Laboratoire d’Aérologie, Toulouse, France
14CNRS Centre d’Etude des Environnements Terrestre et Planétaires, St Maur, France
15CPTEC, Centro de Previsão de Tempo e Estudos Climàticos, Cachoeira Paulista, Brazil
*now at: Université de Reims Champagne-Ardenne/CNRS Groupe de Spectrométrie Moléculaire et Atmosphérique, France

Abstract. HIBISCUS was a field campaign for investigating the impact of deep convection on the Tropical Tropopause Layer (TTL) and the Lower Stratosphere, which took place during the Southern Hemisphere summer in February–March 2004 in the State of São Paulo, Brazil. Its objective was to provide a set of new observational data on meteorology, tracers of horizontal and vertical transport, water vapour, clouds, and chemistry in the tropical UT/LS from balloon observations at local scale over a land convective area, as well as at global scale using circumnavigating long-duration balloons. Overall, the composition of the TTL, the region between 14 and 19 km of intermediate lapse rate between the almost adiabatic upper troposphere and the stable stratosphere, appears highly variable. Tracers and ozone measurements performed at both the local and the global scale indicate a strong quasi-horizontal isentropic exchange with the lowermost mid-latitude stratosphere suggesting that the barrier associated to the tropical jet is highly permeable at these levels in summer. But the project also provides clear indications of strong episodic updraught of cold air, short-lived tracers, low ozone, humidity and ice particles across the lapse rate tropopause at about 15 km, up to 18 or 19 km at 420–440 K potential levels in the lower stratosphere, suggesting that, in contrast to oceanic convection penetrating little the stratosphere, fast daytime developing land convective systems could be a major mechanism in the troposphere-stratosphere exchange at the global scale.

The present overview is meant to provide the background of the project, as well as overall information on the instrumental tools available, on the way they have been used within the highly convective context of the South Atlantic Convergence Zone, and a brief summary of the results, which will be detailed in several other papers of this special issue.

Citation: Pommereau, J.-P., Garnier, A., Held, G., Gomes, A.-M., Goutail, F., Durry, G., Borchi, F., Hauchecorne, A., Montoux, N., Cocquerez, P., Letrenne, G., Vial, F., Hertzog, A., Legras, B., Pisso, I., Pyle, J. A., Harris, N. R. P., Jones, R. L., Robinson, A., Hansford, G., Eden, L., Gardiner, T., Swann, N., Knudsen, B., Larsen, N., Nielsen, J., Christensen, T., Cairo, F., Pirre, M., Marécal, V., Huret, N., Riviére, E., Coe, H., Grosvenor, D., Edvarsen, K., Di Donfrancesco, G., Ricaud, P., Berthelier, J.-J., Godefroy, M., Seran, E., Longo, K., and Freitas, S.: An overview of the HIBISCUS campaign, Atmos. Chem. Phys. Discuss., 7, 2389-2475, doi:10.5194/acpd-7-2389-2007, 2007.
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