Multiangle Aerosol Remote Sensing: From Research Algorithm to Applications

In addition to aerosol optical depth, under favorable observing conditions multi-angle remote sensing offers constraints on near-source aerosol plume height, e.g., from volcanoes, wildfires, and dust storms, as well as aerosol type, which represents constraints on particle size, shape, and single-scattering albedo. We have developed algorithms to derive plume height and particle type information from the NASA Earth Observing System’s Multi-angle Imaging SpectroRadiometer (MISR) instrument. Recent work has included further refinement and extension of the MISR Research Aerosol Retrieval algorithm to better constrain sensor radiometric calibration, to better represent ocean and land surfaces, to better account for the range of natural and anthropogenic aerosol types, and to implement a number of more subtle changes to radiance handling, cloud screening, uncertainty estimation, etc. These changes have resulted in improved aerosol optical depth (AOD) and greatly improved aerosol type retrievals, compared to the MISR Standard algorithm and to aerosol products from other passive remote-sensing instruments.

Importantly, as the retrieval algorithm refinements have advanced, the focus of our efforts under NASA’s ACMAP program is increasingly toward the application of these tools. This includes providing constraints to climate and air quality modeling, and contributing to NASA’s Disaster Response efforts. Specifically, we have developed a global climatology of smoke plume injection heights as part of the AeroCom climate-modeling Biomass Burning experiment, aimed at providing a satellite-based constraint on climate models. Also as part of the AeroCom experiment, we are testing both the widely used GFED smoke emissions inventory and the implied smoke source strength in about 10 individual AeroCom models with AOD snapshots primarily from MODIS. Continuing work includes analyzing smoke-plume injection heights, particle properties, and thermal anomalies for fires in different ecosystems. We have demonstrated a physical approach for constraining air quality modeling outputs with MISR aerosol-type results from the Research Algorithm, and are now applying it to a range of urban areas in different parts of the world. Our MISR-derived maps of plume height and aerosol type for volcanic eruptions at Kilauea were used to initialize regional air quality modeling for the Hawaii region. More generally, we have developed a multi-sensor approach to observing and interpreting volcanic activity from space, including plume dispersion, plume property evolution, as well as some aspects of the underlying geology, applied most recently to the MISR record for multiple volcanoes in Kamchatka and Iceland. This presentation will highlight the key applications to which we are contributing with the 19+ years of MISR and MODIS data, in the context of the underlying tools that make this work possible.