Identifying Dust Events and Deposition over the North Pacific Ocean Using the Entire MODIS Data Records and MERRA-2

Dust aerosols have large environmental and human impacts. They influence the Earth radiation budget by absorbing and reflecting solar energy, alter the hydrological cycle by interacting with cloud and precipitation processes, and affect air quality, visibility and health. Another important aspect of dust is its potential significance as a nutrient source for Earth ecosystems, especially over iron depleted remote oceans. To test the hypothesis that dust influences ocean ecosystems, we need to know when a dust event occurs so that we can then examine ocean ecosystem responses. This is a different problem than creating a dust climatology of monthly and seasonal means. It requires identifying and tracking dust events on the order of a few days to a week, globally. The difficulty, especially outside of frequent dust outflow zones, is that dust can be mixed/misidentified with other aerosols and clouds and it can be transported long distances across continents and oceans. The only hope for an observationally-based dust event identification system across ocean basins is to use satellite observations. Although active sensors such as lidars can identify dust with high confidence and characterize its vertical distribution, these instruments sacrifice spatial coverage in the horizontal and thus risk missing significant events. In this study, we generate a database that documents dust events over the North Pacific basin using the entire Moderate resolution Imaging Spectroradiometer (MODIS) data records. Then we apply MERRA-2 reanalysis data to assist in identifying which events actually deposit particles into the ocean. Using this dataset, we examine the climatology and inter-annual variability of dust events over the North Pacific and evaluate interactions between airborne dust and ocean biology.