Mineral dust transport characterization from combined MISR/MODIS aerosol retrievals for NAAPS transport model validation

Mineral dust is a major airborne atmospheric constituent. Dust plumes frequently cover geographically large areas; they are among the most prominent and commonly visible features in satellite imagery. An understanding of dust amount and particle property evolution during long-range transport is important for characterizing dust environmental impacts and climate forcing. We present a North Africa dust transport study using MISR and MODIS observations of selected dust events during the summer months of 2000 - the timeframe of the Puerto Rico Dust Experiment field campaign. MODIS routinely reports aerosol products over the extended ocean areas, while MISR's instantaneous observations capture dust plumes during several stages of their evolution. As these plumes cross the ocean, MISR's multi- angle retrieval compliments MODIS's nadir-only observations in sun-glint areas, and through sampling of side- scattered light makes it possible to distinguish dust from spherical aerosol components. We analyze MISR and MODIS retrieved aerosol optical thickness and fraction of non-spherical particles, and compare with dust modeling results from the Navy Aerosol Analysis and Prediction System (NAAPS), and as well as available AERONET data. We estimate MISR/MODIS dust removal rates and plume mass observed during multiple stages of transport (close-to-source and progressively down-wind). Our study demonstrates that transport model predictions are needed to fill gaps in MISR/MODIS spatial and temporal coverage, needed for mass flux calculations. We show that NAAPS predictions of dust activity and locations are qualitatively consistent with MISR, MODIS, and AERONET observations. In some cases, NAAPS dust parameterization and deposition rates warrant an improvement, especially at ocean areas close to dust sources.