MODELLING

Chemical transport models are being extensively used to simulate regional loading of different aerosol species under the combined effects of production, dispersion, chemistry and transport in regional and global climate models. Most of these draw the required meteorological fields from reanalysis data and sources from the emission inventories and remain practically untested over the south Asian region. In a first of its kind effort, the performance of three chemical transport models; one regional climate model (RegCM), two chemical transport models - GOCART and CHIMERE – have been evaluated over Indian region, by comparing the simulations with concurrent multi-station measurements. It was shown that all the models failed to simulate the measurements; more so during the winter and pre-monsoon seasons and over mega cities. Of the three models, however, the deviation was lower for CHIMERE. The possible reasons for these deviations included unrealistic parameterization of the advection processes, boundary layer dynamics and inappropriate emission inventories for the Asian region.