Evaluating the impact of assimilating CALIOP-derived aerosol extinction profiles on a global mass transport model

Coupled two/three-dimensional variational (2D/3DVAR) assimilation of aerosol physical properties retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging Spectroradiometer (MISR) and Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite-borne instruments is described for the U. S. Navy Aerosol Analysis and Prediction System (NAAPS) global aerosol mass transport model. Coupled 2D/3DVAR assimilation for NAAPS is evaluated for 48-hr forecast cycles, computed four times daily in six-hour intervals, versus stand-alone 2DVAR assimilation of MODIS and MISR aerosol optical depths (AOD). Both systems are validated against AERONET ground-based sun photometer measurements of AOD. Despite a narrow nadir viewing swath and more than 2700 km of equatorial separation between orbits, satellite lidar data assimilation elicits a positive model response. Improvements in analysis and forecast AOD absolute errors are found over both land and maritime AERONET sites. The primary impact to the model from 3DVAR assimilation is the redistribution of aerosol mass into the boundary layer, though the process is sensitive to parameterization of vertical error correlation lengths. Citation: Zhang, J., J. R. Campbell, J. S. Reid, D. L. Westphal, N. L. Baker, W. F. Campbell, and E. J. Hyer (2011), Evaluating the impact of assimilating CALIOP-derived aerosol extinction profiles on a global mass transport model, Geophys. Res. Lett., 38, L14801, doi:10.1029/2011GL047737.