A52F-04
An Observationally-Constrained Global Dust AOD Suggests a Systematic Underestimation of Dust in Model
Friday, 18 December 2015: 11:05
3012 (Moscone West)
David A Ridley, Massachusetts Institute of Technology, Cambridge, MA, United States, Colette L Heald, Massachusetts Institute of Technology, Civil and Environmental Engineering, Cambridge, MA, United States, Jasper F Kok, University of California Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, CA, United States and Chun Zhao, Pacific Northwest National Laboratory, Richland, WA, United States
Abstract:
The global dust AOD is a useful metric for understanding the impact of dust on the radiative budget and for assessing and constraining dust emission in global models. Using several years of satellite retrievals, sun-photometer measurements and global model AOD, we provide an updated estimate of the present-day global dust AOD. A comprehensive uncertainty analysis encompasses the retrieval uncertainty, sampling issues, bias corrections, and different satellite and model combinations. The estimate is significantly higher than the median of the AEROCOM models (0.028) and is also higher than all the models used as part of this study (MERRAero, CESM, GEOS-Chem and WRF-Chem). This suggests a systematic underestimate of the radiative impact of dust in global models, with implications for the estimates of anthropogenic dust forcing. The discrepancy between modeled and observed global dust AOD stems from a lack of dust from Asian deserts, too vigorous removal in key outflow regions, and missing summertime emissions in Africa. This new observationally-derived dataset provides a benchmark for improving model simulations of dust lifecycle and the radiative impacts of mineral dust.
