Transformation and removal processes for sulfur compounds in the atmosphere as described by a one-dimensional time-dependent diffusion model

• Published in: Atmospheric environment 1978, Vol.12 (1), p.503-509
• Main Authors: Omstedt, Gunnar, Rodhe, Henning
• Format: Article
• Language: English
• ISSN: 0004-6981; 1352-2310
• DOI: 10.1016/0004-6981(78)90232-9

The model is used to simulate vertical profiles of H 2S, SO 2 and SO 4 2− in the atmosphere up to about 8 km. Transformation and wet removal processes are treated as first order reactions with constant rate coefficients and the dry deposition is estimated using deposition velocity parameters. From a systematic study of the sensitivity of the model to variations in some of the key parameters and from a comparison with aircraft measurements of SO 2 and SO 4 2− over Scandinavia the following results are derived. An increase in the value of the deposition velocity in long range transport models beyond about 1cm s −1 has little effect on the estimated dry deposition. As the rate coefficient for the transformation of H 2S to SO 2 varies from 10 to 0.01 h −1 the scale height of H 2S varies from 40 to 1400 m and that of SO 2 (applicable to background air) from 1300 to 3400 m. An average value for the first 30 hours of the rate of transformation of man-made SO 2 to SO 4 2− is probably in the range 0.007 to 0.04 h −1 for European conditions. It is difficult to simulate the observed pattern of wet deposition of sulfur over northern Europe if the wet removal of SO 2 is neglected.