Parameterization of wet deposition of sulfate by precipitation rate

A method for the estimation of wet deposition of sulfate is developed using routinely available meteorological data and the observed airborne sulfate concentration. This approach takes into account different mechanisms of pre cipitation formation that determine sulfate concentration in precipitation water. Four different precipitating cloud types, including cold cloud, warm cloud, stratified layered cloud and convective cloud, according to their p recipitation formations are incorporated differently to estimate sulfate co ncentration in precipitation water. This method is implemented to estimate wet deposition of sulfate in Seoul for the days when the airborne sulfate c oncentration is available. The estimated wet deposition of sulfate shows th at the model slightly overestimates the wet deposition of sulfate especiall y for the warm cloud case while it does underestimate sulfate deposition fo r the Bergeron process in developing precipitation particularly when the in put airborne sulfate concentration is small. The precipitation amount weigh ted mean wet deposition of sulfate obtained from the model, overestimates t hat observed by a factor of 1.6 for this case study. This discrepancy might be associated with non-steady revolutional features of precipitating cloud s and the resolvable scaling difference between the model and observation. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.