to study vertical and horizontal transport in upper troposphere and lower stratosphere (UTLS) including contribution of meso- and small scale waves;

to assess the quality of current operational global meteorological analyses at the tropics (temperature, winds);

to explore the mechanism which controls the amount of water vapour reaching the stratosphere (dehydration) and the possible cause of its trend in the stratosphere;

to assess the impact on chemistry of short lived active chemical species from pollution and biomass burning lifted by convection and NOx production by lightning;

to assess the impact of aerosols on the formation of thin sub-visible cirrus at tropopause level and their impact on chemistry and radiation transfer;

to validate satellite ODIN, ESA-ENVISAT, NASA-SAGE III atmospheric chemistry measurements at the tropics.