Feasibility of measurements of water vapor and ice clouds in the tropical UT/LS region with MIPAS/Envisat Original Research Article

On 1 March 2002, the European research satellite Envisat has been successfully launched. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board is a limb viewing mid-infrared high-resolution spectrometer. Among numerous atmospheric parameters, water vapor and temperature profiles will be retrieved from spectral data in an altitude range from 5 km up to the mesosphere. In this paper, we analyze MIPASʹ potential for spatially resolved water vapor measurements in the tropical tropopause region. A detailed pre-launch retrieval study, which includes error sources like random noise, smoothing error and error contributions due to interfering species, has shown that significant results can be obtained down to 10 km. The achievable accuracy is between 10% and 20% depending on the altitude range. By making use of a finer sampling grid in the tangent altitude domain a vertical resolution as good as 1.5–2 km can be reached. The impact of thin cirrus clouds on the infrared spectra measured by MIPAS has been simulated.