Introduction

The experimental approach is to combine 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, in collaboration with IPMet and Brazilian research institues , simultaneous observations at La Réunion and state of the art transport, microphysical, radiative and chemical modelling.

HIBISCUS will combine in situ and remote measurements using a variety of small and light weight instruments flown on long duration as well as short duration balloons. Long duration balloons of two types, constant level super-pressure balloons and Infra-Red Montgolfier , flown for several weeks around the world will provide measurements at global scale:

in situ measurements of meteorology, ozone and water vapour at constant level at, and immediately above the tropopause (80 and 60 hPa)
remote sensing in the upper troposphere and the lower stratosphere of temperature, aerosols, clouds and of chemical composition from Infra-Red Montgolfier flying in the lower stratosphere, at 26-27 km altitude during daytime and 18-24 km during night-time.

In addition, several instruments flown together with small short duration balloons will provide co-located high resolution vertical profiles of tracers, aerosols, clouds, water, UV radiation, ozone and chemical composition.

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.