ModIs Dust AeroSol (MIDAS): a global fine-resolution dust optical depth data set

Antonis Gkikas,Nikos Hatzianastassiou,Eleni Marinou,Stelios Kazadzis,Enza Di Tomaso,Vassilis Amiridis,Carlos Pérez García-Pando,Emmanouil Proestakis,Alexandra Tsekeri

doi:10.5194/amt-14-309-2021

Abstract

Abstract. Monitoring and describing the spatiotemporal variability in dust aerosols is crucial for understanding their multiple effects, related feedbacks, and impacts within the Earth system. This study describes the development of the ModIs Dust AeroSol (MIDAS) data set. MIDAS provides columnar daily dust optical depth (DOD) at 550 nm at a global scale and fine spatial resolution (0.1∘ × 0.1∘) over a 15-year period (2003–2017). This new data set combines quality filtered satellite aerosol optical depth (AOD) retrievals from MODIS-Aqua at swath level (Collection 6.1; Level 2), along with DOD-to-AOD ratios provided by the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) reanalysis to derive DOD on the MODIS native grid. The uncertainties of the MODIS AOD and MERRA-2 dust fraction, with respect to the AEronet RObotic NETwork (AERONET) and LIdar climatology of vertical Aerosol Structure for space-based lidar simulation (LIVAS), respectively, are taken into account for the estimation of the total DOD uncertainty. MERRA-2 dust fractions are in very good agreement with those of LIVAS across the dust belt in the tropical Atlantic Ocean and the Arabian Sea; the agreement degrades in North America and the Southern Hemisphere, where dust sources are smaller. MIDAS, MERRA-2, and LIVAS DODs strongly agree when it comes to annual and seasonal spatial patterns, with colocated global DOD averages of 0.033, 0.031, and 0.029, respectively; however, deviations in dust loading are evident and regionally dependent. Overall, MIDAS is well correlated with AERONET-derived DODs (R=0.89) and only shows a small positive bias (0.004 or 2.7 %). Among the major dust areas of the planet, the highest R values (>0.9) are found at sites of North Africa, the Middle East, and Asia. MIDAS expands, complements, and upgrades the existing observational capabilities of dust aerosols, and it is suitable for dust climatological studies, model evaluation, and data assimilation.

Highlights

Among tropospheric and stratospheric aerosol species, dust aerosol is the most abundant component in terms of mass, contributing more than half of the global aerosol amount (Textor et al, 2006; Zender et al, 2011)
We presented the MIDAS (ModIs Dust AeroSol) dust optical depth (DOD) data set, developed via the synergistic implementation of MODerate resolution Imaging Spectroradiometer (MODIS)-Aqua aerosol optical depth (AOD) and dust fraction extracted from colocated MERRA-2 reanalysis outputs
The derived fine-resolution (0.1◦ × 0.1◦) global data set between 2003 and 2017 provides DOD both over continental and oceanic areas, in contrast to similar available satellite products restricted over land surfaces (Ginoux et al, 2012), making a thorough and consistent description of dust loads, over the sources and over downwind regions, feasible

Summary

Introduction

Among tropospheric and stratospheric aerosol species, dust aerosol is the most abundant component in terms of mass, contributing more than half of the global aerosol amount (Textor et al, 2006; Zender et al, 2011). Preferential sources of dust aerosols are located in areas where precipitation is low, favoring aridity, whereas a significant contributing factor is the accumulation of alluvial sediments. Such regions comprise deserts, dry lake beds, and ephemeral channels (e.g., Middleton and Goudie, 2001; Prospero et al, 2002; Ginoux et al, 2012).

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