In the last 5 yr, the capabilities of earth-observing satellites and the technological tools to share and use satellite data have advanced sufficiently to consider using satellite imagery in conjunction with ground-based data for urbanscale air quality monitoring. Satellite data can add synoptic and geospatial information to ground-based air quality data and modeling. An assessment of the integrated use of ground-based and satellite data for air quality monitoring, including several short case studies, was conducted. Findings identified current U.S. satellites with potential for air quality applications, with others available internationally and several more to be launched within the next 5 yr; several of these sensors are described in this paper as illustrations. However, use of these data for air quality applications has been hindered by historical lack of collaboration between air quality and satellite scientists, difficulty accessing and understanding new data, limited resources and agency priorities to develop new techniques, ill-defined needs, and poor understanding of the potential and limitations of the data. Specialization in organizations and funding sources has limited the resources for cross-disciplinary projects. To successfully use these new data sets requires increased collaboration between organizations, streamlined access to data, and resources for project implementation.
INTRODUCTIONUrban air quality traditionally has been monitored with networks of ground monitoring stations and the use of models that evaluate emissions and predict changes in air quality at discrete points. Satellite remote sensing may provide a synoptic picture of air quality in an urban airshed, including information on sources for isolated events. Use of satellite data could help air quality professionals identify the location of peak concentrations and determine the concentration gradients between surface monitoring stations. To date, satellite sensors have yielded limited quantitative information for air quality compared with ground-based monitoring, yet the potential exists for quantitative applications. The integrated use of these two sources of data and models should better enable policy decisions and increase scientific understanding of an urban airshed than either method alone. Specifically, satellite sensors could provide a broad view of urban haze and help determine the impact on urban air quality by local fires, dust storms, or transport of pollutants from more distant sources, including those crossing national or regional boundaries. 1 Satellite remote-sensing