Allen Chu - 613 Seminar Series

University of Maryland Baltimore County

Aerosol optical depth (AOD) retrieved from satellite remote sensing data has been widely applied to air quality monitoring and assessment of PM2.5. The broad coverage of satellite measurements is especially useful in places where no surface observations are available. However, the results derived using simple relationship (disregarding aerosol vertical distribution) revealed good and also relatively poorer correlation between AOD and PM2.5.  Something must be missing. Vertical mixing height (or boundary layer height) and humidification (f(RH)) are considered to be major contributing factors.  The increasingly available lidar-based aerosol extinction profiles provide insights into the boundary layer as well as residual above it. The method that normalizes AOD by haze layer height (HLH) is shown to be season-independent in correlating with mean PBL extinction with correlation greater than 0.95. Mean PBL extinction (MPE) is derived by AOD within PBL over PBL height as opposed to near surface extinction (NSE) ­ the extinction value at the lowest altitude possibly measured by lidar. The former is used to validate the assumption while the latter is used to constrain f(RH).  Airborne HSRL and MPLNet lidar are used. The deployment of DRAGON is unique to provide the baselined relationship for satellite AOD products. In this talk, the results of DISCOVER-AQ field campaign in Baltimore-Washington (2011) and earlier aircraft campaign in San Joaquin Valley (2007) will be presented.