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The source of chemical species involved in stratospheric ozone depletion at global-scale, lies in the tropics where they are transported vertically from surface level to the tropopause by deep convection. Among most important chemical species and aerosols specific to the tropics, which could have an impact on ozone and climate in the future are: the still unknown volume of NOx production by lightning, a prerequisite to evaluate the impact of aircraft, and the chemical impact of biomass burning, change of agricultural practices and pollution from fast growing population in tropical developing countries on the Upper Troposphere and Lower Stratosphere (UT/LS).
HIBISCUS is to study a number of dynamical, microphysical, radiative and chemical aspects of the UT/LS related to deep convection in the tropics, detailed in the list of specific objectives. HIBISCUS is a European project in scientific and technical cooperation with IPMet/UNESP , the Institute for Meteorological Research of the State University of Sao Paulo . The HIBISCUS team includes a number of European research groups as well as Brazilian partners associated with the project.
The experimental approach, based on successful techniques developed for the Arctic European campaigns in the 90's, is to combine in situ measurements by a variety of instruments flown on small balloons for few hours in Brazil during the summer convective season and on long duration balloons for several weeks around the world in the tropics, with support of ground-based measurements in Brazil , simultaneous observations at La Réunion and state of the art transport, microphysical, radiative and chemical modelling. The balloons developed by the CNES Balloon Division are operated in cooperation with IPMet/UNESP. Two field campaigns were planned at Bauru (State of Sao Paulo, Brazil) at the IPMet/UNESP balloon facility. The first, dedicated to the validation of ENVISAT and the testing of new instrumentation, named the ENVISAT pre-HIBISCUS campaign, was in February 2003. The main HIBISCUS campaign was in January/February/March 2004 in coordination with the aircraft of the TROCCINOX campaign.
Specific anticipated deliverables are: a validation of satellite (particularly ENVISAT) measurements in the tropics and the determination of the altitude down to which their measurements could be reliable ; a study of the accuracy of global operational meteorological models (particularly ECMWF) in the tropics and of possible causes of deviations (i.e. mesoscale waves); an evaluation of the amplitude of NOx production by lightning and alternatively lifting from biomass burning and urban pollution needed to better understanding the relative impact of aircraft exhaust, the measurement of the frequency and geographic distribution of sub-visible cirrus at global scale.
HIBISCUS is a shared cost project supported by the European Commission and partners national research agencies.
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