First results on tropospheric observations by the Global Ozone Monitoring Experiment, GOME, on ERS 2

ERS2 based GOME provides UV-VIS-spectra of nadir scattered sunlight which carries the absorption signals of atmospheric compounds. So far ozone, nitrogen dioxide, chlorine dioxide, and bromine monoxide have been identified. As tropospheric chemistry is of high interest for the science community some effort was made to identify formaldehyde in the spectra taken by GOME. Formaldehyde as an important intermediate in the oxidation cycle of hydrocarbons is expected to occur in regions of strong and extended photochemical activity which are mostly found in the lower layers of the troposphere. In this contribution first observations of formaldehyde are described in plumes of burning savannas in Africa and in a smog episode which covered the upper Rhein area around Frankturt/Ludwigshaten in Germany. So far the weak formaldehyde absorptions could only be identified against a spectrum from the same or from close orbits containing background levels of formaldehyde absorptions. The plume above Africa and above the Atlantic Ocean contains an additional vertical column of 1.6 x 1016 molec/cm2 which corresponds to 2.5 or 1.4 ppb in a layer of 3 or 6 Km from ground, respectively.