The use of both active and passive NASA remote sensing instruments to study aerosols, evaluate predictive aerosol models, and assess aerosol distribution and outflow in the Mexico City region is presented. Measurements and model simulations of aerosol optical depth (AOD) during the Mega-city Initiative—Local and Global Research Observations (MILAGRO), INTEX-B (Intercontinental Chemical Transport Experiment-B) campaign are examined. Two NASA instruments provided the AOD measurements examined here; these instruments are the NASA Langley airborne High Spectral Resolution Lidar (HSRL) deployed on the NASA Langley B200 King Air aircraft and the spaceborne MODIS (MODerate Resolution Imaging Spectroradiometer). Participation in MILAGRO was to support the Department of Energy Atmospheric Science Program Megacity Aerosol eXperiment in MEXico City (MAX-Mex) project.

AOD measurements from the MODIS (550 nm) instrument aboard the Terra spacecraft were compared with preliminary retrievals of AOD from the HSRL (532 nm) aboard the King Air B200. Initial comparisons were conducted on 12 and 13 March 2006, at which time the King Air B200 flight track intersected the ground track of the Terra spacecraft. AOD was derived from the HSRL measurements by integrating the aerosol extinction profiles between 0.1 and 7km. On 12 and 13 March, the correlation between HSRL and MODIS AOD values were 0.774 and 0.667 respectively. The two data sets were further analyzed using a neural network to provide a better comparison by adjusting the weights of data variation. After neural network analysis, the correlation increased to 0.796 (2.84%) and 0.858 (28.6%) respectively.

The HSRL and MODIS AOD measurements were also used to examine forecast simulations of AOD from the Sulfur Transport dEposition Model (STEM). Regression and correlation analyses were performed on AOD values for MODIS, HSRL and STEM. Visualizations were constructed to show trends among the three instruments over the time of flight. On 12 March, STEM correlated well with HSRL and MODIS (r = 0.979 and 0.744 respectively). On 13 March, the STEM forecasts correlated poorly with HSRL and MODIS (r = 0.013 and 0.059 respectively).

The potential use of measurements from future spaceborne sensors such as the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and the Aerosol Polarimetry Sensor (APS) instrument onboard Glory for similar studies will also be discussed.