Aerosols

Abstract

Our appreciation of aerosols’ role in climate change has grown over the past 25 years, in part due to the contributions made by remote sensing. First estimates of the impacts transported aerosols have on the atmospheric energy balance, on clouds and the hydrological cycle, on larger-scale atmospheric circulation, and on human health have been made. An understanding has developed for the need to combine detailed physical and chemical measurements from aircraft and ground stations and extensive constraints on aerosol optical depth, type, and vertical distribution from satellites, with numerical models that can simulate present and predict future conditions. However, much remains to be done. For planning purposes, the accuracy of measurements needed to assess aerosol direct radiative effect must be improved, and uncertainties in aerosol indirect effects on clouds must be reduced. Techniques for systematically constraining models with satellite and suborbital data need to be developed, both to test model parameterizations of aerosol sources, cloud processes, etc., and to assess the uncertainties in the resulting simulations. Based on past experience, this can be achieved, provided we continue to develop and deploy the instruments, improve the models, and maintain the research community, which have carried the field to this point.