Can Remote Sensing Products Detect the Air Quality Signal due to Aviation Emissions?

Regional air quality model predictions attributable to aircraft for total column aerosol optical depth (AOD) and vertically resolved aerosol extinctions/NO2 concentrations are compared against MODIS AOD, CALIPSO aerosol extinctions, and SAGE aerosol extinctions/NO2 concentrations. The goal of this work is to determine if an aircraft-specific signal is present in these metrics and how it compares to remote sensing products. In general, the modeled aircraft signal to aerosol based metrics (optical depth and extinctions) were relatively low (0.03-0.07% of the total modeled signal) limiting comparisons while the NO2 signal at cruise levels (58% of the total modeled signal) provided a better basis for comparison. Introduction To evaluate air quality model performance, results are traditionally compared against ground based observation networks such as the Chemical Speciation Network (CSN), the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, and the SouthEastern Aerosol Research and Characterization (SEARCH) network. These ambient monitoring networks, located at fixed locations throughout the U.S., directly measure ground based concentrations. In turn, these ground based measurements are compared against first layer model based predictions. Given that the intended use of regional air quality model results often include regularity decision support or assessing health impacts, these ground based evaluations are considered adequate in determining general model performance for these intended applications. However, this approach is not without limitations as ground based observation networks provide relatively sparse coverage and no measurements above ground level. An alternative approach currently being employed to evaluate model results is through the use of remote sensing products obtained via satellites. These satellites, which typically retrieve various forms of radiation (IR, visible, etc.), can potentially provide more widespread coverage as well as vertical profiles of measured quantities, depending on the satellite, sensor, and retrieval techniques used to obtain the measurement. Sensors are categorized as either active or passive. Active sensors (e.g. RADAR and