The Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Mission is a five-year multisite experiment to better understand the relationship between satellite- measured variables (columnar) with surface concentrations, required for air quality assessment and regulation. The first DISCOVER-AQ experiment was held in the Baltimore-Washington urban corridor during July 2011 and involved thirteen lidars, a network of sunphotometers, sondes and two aircraft to provide the vertical profiles needed to close the vertical column with surface measures. UMBC operated one of the lidars in a scanning configuration to obtain 8 km cross-sectional scans across the I-95 corridor. This will be the basis of an on-going study in Baltimore for obtained volumetric aerosol information over the urban area. We use the DISCOVER-AQ data to determine whether gradients in aerosol can be determined on the microscale and the relevance to satellite retrievals of air quality over an urban setting.