An overview of the HIBISCUS campaign

Jean-Pierre Pommereau (1) , Anne Garnier (1) , G. Held (2) , A.-M. Gomes (2) , Florence Goutail (1) , George Durry (1) , François Borchi (1) , Alain Hauchecorne (1) , Nadège Montoux (1) , P. Cocquerez (3) , G. Letrenne (3) , F. Vial (4) , Albert Hertzog (5) , B. Legras (4) , I. Pisso (4) , J. A. Pyle (5) , N. R. P. Harris (5) , R. L. Jones (5) , A. Robinson (5) , G. Hansford (5) , L. Eden (5) , T. Gardiner (6) , N. Swann (6) , B. Knudsen (7) , N. Larsen (7) , J. Nielsen (7) , T. Christensen (7) , F. Cairo (8) , Michel Pirre (9) , V. Marécal (9) , Nathalie Huret (9) , E. Riviére (9) , H. Coe (10) , D. Grosvenor (10) , K. Edvarsen (11) , G. Di Donfrancesco (12) , P. Ricaud (13) , Jean-Jacques Berthelier (14) , Michel Godefroy (14) , Elena Seran (14) , K. Longo (15) , S. Freitas (15)

1 SA - Service d'aéronomie
2 IPMet - Instituto de Pesquisas Meteorológicas
3 CNES - Centre National d'Études Spatiales [Toulouse]
4 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
5 CAM - University of Cambridge [UK]
6 NPL - National Physical Laboratory [Teddington]
7 DMI - Danish Meteorological Institute
8 ISAC - Istituto di Scienze dell'Atmosfera e del Clima
9 LPCE - Laboratoire de physique et chimie de l'environnement
10 UMIST - University of Manchester Institute of Science and Technology
11 NILU - Norwegian Institute for Air Research
12 ENEA - Italian National agency for new technologies, Energy and sustainable economic development [Frascati]
13 LAERO - Laboratoire d'aérologie
14 CETP - Centre d'étude des environnements terrestre et planétaires
15 CPTEC - Center for Weather Forecasting and Climate Studies [São Paulo]

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.

Domaines: Océan, Atmosphère

Jean-Pierre Pommereau, Anne Garnier, G. Held, A.-M. Gomes, Florence Goutail, et al.. An overview of the HIBISCUS campaign. Atmospheric Chemistry and Physics Discussions, 2007, 7 (1), pp.2389-2475. ⟨hal-00328044v1⟩