Optical monitoring of aerosols in urban regions

Monitoring of the optical and physical properties of aerosol particles is very important for assessment of their effect on climate, radiation budget or healt (e.g., it is well-known that only particles of specific size may cause respiration problems). It has been suggested recently that tropospheric aerosols can contribute substantially to climate changes on Earth by causing a direct radiative forcing comparable in magnitude to the expected climate forcing by greenhouse gases. It is, therefore, desireable and necessary to retrieve accurate information about the territorial distribution and physical properties of aerosol particles. However, the problem with aerosols is that mineral and dust particles have nonspherical shapes thus making questionable the applicability of standard retrieval algorihms. The project will focus on the solution of these problems. Aerosol characteristics will be gained by optical contactless methods (based on light scattering theory). An additional aim is to investigate aerosol optical properties and relate the optical parameters with aerosol mass and specific aerosol species. The main properties of the aerosol particles for such studies are (i) size/shape distribution, for the different aerosol types (e.g. inorganic species black smoke) averaged on the prevailing condition; (ii) the scattering phase function at large angles of these aerosol types; (iii) the single-scattering albedo by theparticles; (iv) lifetime of the aerosol particles; and (v) the effect of atmospheric processes on the aerosol particles. An identification of particle size/shape distributions and in particular, temporal and spatial changes in the relative concentrations of different size particles, can yield considerable insight into the sources and sinks of the particles. We expect that an accuracy of retrieval algorithms for aerosol size distribution will differ from region to region (because of different aerosol type). Both, the theoretical as well as the experimental results of our project may therefore be valuable for aerosol research in geographically various territories.