High spatial resolution satellites as a complement to atmospheric modeling and to ground measurements for air-quality monitoring

Abstract

High spatial resolution (HSR) satellite observations, while not frequent enough to follow air pollution's dynamic fluctuations, can provide spatially resolved information related to urban air quality. More specifically, HSR satellites can provide independent "spatial measurements" on the columnar aerosol optical thickness in the visible (AOTV). When normalized to ground level, AOTV can be correlated to fine aerosol concentrations, and when monitored over long or representative periods it could be used as an air-quality indicator to bridge the gap between "point measurements" by ground-based sampling, and "spatial estimations" by atmospheric modelling. We briefly review in this paper the methods we developed to map AOTV over urban areas from HSR satellites; we then describe qualitative AOTV validation procedures for the case of Athens. We finally present preliminary quantitative results from a pilot application where we compared data on air quality acquired using the three tools (i.e., satellite observations, atmospheric modelling and ground measurements) over two polluted European sites. This comparison showed good agreement between satellite-derived AOTV, on the one hand, and ground-level aerosol precursor concentrations and modelling-derived pollutant flow patterns on the other. These preliminary results encouraged an in-depth investigation of the benefits from the complementary use of these three techniques for integrated air-quality monitoring. During four pilot campaigns foreseen in the framework of the ICAROS NET project, we plan to collect detailed atmospheric data and run numerical models in conjunction with the satellite passages.