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Motivated by the ongoing debates about the relative contribution of specific North African dust sources to the transatlantic dust transport to the Amazon Basin, the current study integrates a suite of satellite observations into a novel trajectory analysis framework to investigate dust transport from the leading two North African dust sources, namely, the Bodélé depression and El Djouf. In particular, this approach provides observation‐constrained quantification of the dust's dry and wet deposition along its transport pathways and is validated against multiple satellite observations. The current large ensemble trajectory simulations identify favorable transport pathways from the El Djouf across the Atlantic Ocean with respect to seasonal rain belts. The limited potential for long‐range transport of dust from the Bodélé depression is attributed to the currently identified extensive near‐source dust removal primarily by dry and wet deposition during boreal winter and summer, respectively. Plain Language Summary: North African deserts have been reported to export ~200 million tons of dust per year to the tropical Atlantic Ocean, degrading air quality over the Caribbean Islands in boreal summer and supplying nutrients to fertilize the Amazon Rainforest in boreal winter and spring through transatlantic dust transport. It has been assumed that the Bodélé depression is the main contributor to this transatlantic dust transport and Amazonian dust fertilization in boreal winter. However, these claims have not been supported by geochemical analysis. Here, we integrate a suite of satellite observations into a novel trajectory analysis framework to investigate dust transport from the leading two North African dust sources, namely, the Bodélé depression and El Djouf, and provide the first ever observation‐constrained quantification of the dust's dry and wet deposition along its transport pathways. The approach yields the novel observational finding that the El Djouf is the preferred source of intercontinental transport across the Atlantic Ocean rather than the Bodélé depression, bridging the geochemical impact of North African minerals on the Amazon Basin to the specific dust origin. Key Points: The current trajectory simulations quantify observation‐derived dust deposition and capture the observed three‐dimensional dust distributionEl Djouf is the preferred source of the transatlantic dust transport, due to favorable transport pathways with respect to seasonal rain beltsExtensive near‐source dust deposition supports the observed limited potential for long‐range transport of dust from the Bodélé depression [ABSTRACT FROM AUTHOR]

The Multi-angle Imaging SpectroRadiometer (MISR) instrument has been operational on the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Terra satellite since early 2000, creating an extensive data set of global Earth observations. Here we introduce the latest version of the MISR aerosol products. The level 2 (swath) product, which is reported on a 4.4 km spatial grid, is designated as version 23 (V23) and contains retrieved aerosol optical depth (AOD) and aerosol particle property information derived from MISR's multi-angle observations over both land and water. The changes from the previous version of the algorithm (V22) have significant impacts on the data product and its interpretation. The V23 data set is created from two separate retrieval algorithms that are applied over dark water and land surfaces, respectively. Besides increasing the horizontal resolution to 4.4 km compared with the coarser 17.6 m resolution in V22 and streamlining the format and content, the V23 product has added geolocation information, pixel-level uncertainty estimates, and improved cloud screening. MISR data can be obtained from the NASA Langley Research Center Atmospheric Science Data Center at https://eosweb.larc.nasa.gov/project/misr/misr%5ftable (last access: 11 October 2019). The version number for the V23 level 2 aerosol product is F13_0023. The level 3 (gridded) aerosol product is still reported at 0.5∘×0.5∘ spatial resolution with results aggregated from the higher-resolution level 2 data. The format and content at level 3 have also been updated to reflect the changes made at level 2. The level 3 product associated with the V23 level 2 product version is designated as F15_0032. Both the level 2 and level 3 products are now provided in NetCDF format. [ABSTRACT FROM AUTHOR]

The Multi-angle imaging spectroradiometer (MISR) land-surface (LS) bidirectional reflectance factor (BRF) product (MILS_BRF) has unique semi-simultaneous multi-angle sampling and global coverage. However, unlike on-satellite observations, the spatio-temporal characteristics of MILS_BRF data have rarely been explicitly and comprehensively analysed. Results from 5-yr (2011–2015) of MILS_BRF dataset from a typical region in central Northeast Asia as the study area showed that the monthly area coverage as well as MILS_BRF data quantity varies significantly, from the highest in October (99.05%) through median in June/July (78.09%/75.21%) to lowest in January (18.97%), and a large data-vacant area exists in the study area during four consecutive winter months (December through March). The data-vacant area is mainly composed of crop lands and cropland/natural vegetation mosaic. The amount of data within the principal plane (PP) ±30° (nPP) or cross PP ±30° (nCP), varies intra-annually with significant differences from different view zeniths or forward/backward scattering directions. For example, multiple off-nadir cameras have nPP but no nCP data for up to six months (September through February), with the opposite occurring in June and July. This study provides explicit and comprehensive information about the spatio-temporal characteristics of product coverage and observation geometry of MILS_BRF in the study area. Results provide required user reference information for MILS_BRF to evaluate performance of BRDF models or to compare with other satellite-derived BRF or albedo products. Comparing this final product to on-satellite observations, what was found here reveals a new perspective on product spatial coverage and observation geometry for multi-angle remote sensing. [ABSTRACT FROM AUTHOR]

Dust from North Africa has been reported to affect the air quality over Caribbean Islands and southeastern United State, as well as supplying nutrients to fertilize the Amazon forest. However, the relative contribution from North Africa dust sources, namely the Bodélé depression and West African deserts, has been debated among different observational and modeling studies. In the current study, dust transport from the Bodélé depression and West African desert are investigated using an observationally constraint, advanced trajectory model that quantifies both dry and wet deposition along trajectory, based on observations of precipitation amount and cloud properties, and is initiated by stereo observations of dust plume height from the Multiangle Imaging SpectroRadiometer (MISR) instrument. Our advanced trajectory model provides an encouraging tool for investigating dust transport, given its capability at successful capturing the observed horizontal and vertical structures of dust transport across the Atlantic.Based on the advanced trajectory modeling, we found the West African deserts contributes substantially more dust than the Bodélé depression to the trans-Atlantic transport in both boreal winter and summer. The relatively contribution from the two North African dust sources are mainly due to differentiated dust transport pathways. For dust particles emitted from both dust sources, wet deposition, primarily driven by substantial rainfall associated with Intertropical Convergence Zone over ocean and intertropical rainbelt over land, overwhelms dry deposition and largely reduces the amount of dust transport to south America in boreal winter and Central and North Americas in boreal summer. According to the precise observation of dust plume height and motion by MISR, substantial removal and suppression of dust plumes occur near the Bodélé depression, supporting the limited potential for long-range transport of dust from the Bodélé depression revealed by the current advanced trajectory modeling. [ABSTRACT FROM AUTHOR]