Quantifying the uncertainty in estimates of the dust radiative forcing based on the NASA Earth Surface Mineral Dust Source InvesTigation data products

Earth system model calculations of the radiative forcing of atmospheric dust are highly uncertain, due in part to large uncertainties in current data on the mineral composition of dust source regions. The Earth Surface Mineral Dust Source InvesTigation (EMIT) will place an imaging spectrometer aboard the International Space Station in order to better constrain global dust mineralogy. An important question for any mission is whether the retrieved quantities will be constrained well enough to actually reduce uncertainties in downstream results. In order to test this, we use spectroscopic and atmospheric models to simulate the EMIT mission and quantify the subsequent reduction in uncertainties associated with estimates of surface properties and of dust radiative forcing in a simplified one-dimensional framework. Using existing literature, we place prior distributions over mineral abundances and, by extension, over dust radiative forcing. We then simulate EMIT retrievals of the full distribution of possible surfaces over several test regions, using the retrieved mineralogies to initialize the Single Column Atmospheric Model and sample the posterior distributions over dust radiative forcing. This framework is naturally extensible to a variety of uncertainty quantification and sensitivity studies for the EMIT mission and other imaging spectrometers.

A portion of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under sponsorship by the National Aeronautics and Space Administration (NASA). Copyright 2019 California Institute of Technology. All Rights Reserved. US Government Support Acknowledged.