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Convective Troposphere-to-Stratosphere Transport in the Tropics as seen by ODIN, CALIPSO, GOMOS, and TRMM satellite observations

Jean-Pierre Pommereau(1), Jean-Paul Vernier(1), Anne Garnier(1), Jacques Pelon(2), Alain Hauchecorne(1) and Philippe Ricaud(3)

(1) CNRS LATMOS, BP 3, 91371 Verrières le Buisson, France
(2) CNRS UPMC, 4 Place Jussieu, 75005 PARIS, France
(3) Université de Toulouse, CNRS, 14 Av Edouard Belin, 31400 Toulouse, France

Abstract

The analysis of the data collected over Brazil, Northern Australia and Africa from balloons and high altitude aircraft during the recent HIBISCUS, TROCCINOX, SCOUT-O3 and AMMA European campaigns, has led to significant revision in the understanding of troposphere-to-stratosphere transport (TST). Repeated observations of strong updrafts of adiabatically cooled and washed-out tropospheric air rich in chemical and greenhouse species by convective overshooting over the three continents, suggests a high frequency of occurrence of such phenomena over land in contrast to their generally assumed scarcity. But still open is the question of importance of those events on TST at global scale, which cannot be answered by local measurements only. This was explored from seasonal changes of tracers concentration in the lower stratosphere provided by satellites, N2O from ODIN, aerosols from CALIPSO lidar backscatter measurements calibrated with GOMOS extinction, all displaying strong injection of tropospheric air up to 20 km in the tropics during the convective summer season. Consistent with the seasonal variation of overshooting volume reported by the TRMM precipitation radar but in contradiction with global scale models all ignoring small scale overshooting, these results suggest that the mechanism could play a major, if not dominant, role in troposphere-to-stratosphere transport in contrast to the generally evoked slow ascent by radiative heating.

 

Workshop presentation