THE TROPOSPHERIC DISTRIBUTION OF FORMALDEHYDE DURING TROPOZ-II

A series of 149 measurements of the HCHO mixing ratio were made betwee n 0 and 10 km altitude and 70 degrees N to 60 degrees S latitude durin g TROPOZ II. The data show a vertical decrease of the HCHO mixing rati o with altitude at all latitudes and a broad latitudinal maximum in th e HCHO mixing ratio between 30 degrees N and 30 degrees S at all altit udes. The measured mixing ratios of HCHO are considerably higher than those expected from CH4 oxidation alone, but agree broadly with the av erage latitude by altitude distribution of HCHO derived by a 2D model including emissions of C-1-C-7 hydrocarbons. A number of the regional scale deviations of the measured HCHO distribution from the average mo delled one can be explained in terms of the local wind field.