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Abstract. While stand alone satellite and model aerosol products see wide utilization, there is a significant need in numerous atmospheric and climate applications for a fused product on a regular grid. Aerosol data assimilation is an operational reality at numerous centers, and like meteorological reanalyses, aerosol reanalyses will see significant use in the near future. Here we present a standardized 2003–2013 global 1 × 1° and 6-hourly modal aerosol optical thickness (AOT) reanalysis product. This data set can be applied to basic and applied Earth system science studies of significant aerosol events, aerosol impacts on numerical weather prediction, and electro-optical propagation and sensor performance, among other uses. This paper describes the science of how to develop and score an aerosol reanalysis product. This reanalysis utilizes a modified Navy Aerosol Analysis and Prediction System (NAAPS) at its core and assimilates quality controlled retrievals of AOT from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Multi-angle Imaging SpectroRadiometer (MISR) on Terra. The aerosol source functions, including dust and smoke, were regionally tuned to obtain the best match between the model fine- and coarse-mode AOTs and the Aerosol Robotic Network (AERONET) AOTs. Other model processes, including deposition, were tuned to minimize the AOT difference between the model and satellite AOT. Aerosol wet deposition in the tropics is driven with satellite-retrieved precipitation, rather than the model field. The final reanalyzed fine- and coarse-mode AOT at 550 nm is shown to have good agreement with AERONET observations, with global mean root mean square error around 0.1 for both fine- and coarse-mode AOTs. This paper includes a discussion of issues particular to aerosol reanalyses that make them distinct from standard meteorological reanalyses, considerations for extending such a reanalysis outside of the NASA A-Train era, and examples of how the aerosol reanalysis can be applied or fused with other model or remote sensing products. Finally, the reanalysis is evaluated in comparison with other available studies of aerosol trends, and the implications of this comparison are discussed.

The Arabic word “haboob,” meaning “strong wind,” describes a weather phenomenon characterized by immense walls of blowing sand and dust. Common to many parts of the Middle East, northern Africa, and the southwestern United States, haboobs are spawned by strong mesoscale downdrafts, making their prediction by coarse‐grid numerical models difficult in comparison to dust forced by synoptic‐scale dynamics. The United Arab Emirates Unified Aerosol Experiment (UAE2), an extensive field program conducted over the southeastern Arabian Peninsula during the summer of 2004, provided a unique opportunity to observe the haboob activity common to this region by way of a large assortment of satellite, radar, lidar, and meteorological station network observations. Here, we present results based on the UAE2 data set which add insight to the formation processes, multiscale structure, and transient behavior of haboobs as well as their potential importance to the regional aerosol burden. Satellite imagery and surface radar data assisted in the interpretation of highly dynamic storm evolution and outflow interactions. An idealized model of haboob dust production, parameterized by the strength and duration of the downburst, suggested that haboobs could be responsible for a nonnegligible component of the regional‐scale total dust production (up to 30% over a 1000 × 1000 km domain).

As part of the United Arab Emirates Unified Aerosol Experiment (UAE2), the size distribution and chemistry of dust particles were measured for the months of August and September 2004 at an Arabian Gulf coastal site impacted by dust from several sources within southwest Asia. The characteristics of common mode dust (0.8 < dp < 10 μm) were examined using an aerodynamic particle sizer (APS), a DRUM cascade impactor, and AERONET Sun/sky retrievals. While size properties from these distinct methods do correlate, accurate dust measurement is still an outstanding challenge. But when instruments are applied consistently in the correct context, the dynamics of dust particle size can be accurately studied. Here, observations are used to study the stability of dust size and chemistry characteristics. We found that dust particle size, chemistry, and morphology appear to be fairly static from individual sources, confirming preliminary hypotheses based on large‐scale observations of Saharan dust. Thus, our data provide experimental evidence that on regional scales, common mode dust is not functionally impacted by production wind speed, but rather influenced by soil properties such as geomorphology or roughness length. Similarly, we found transport processes from the mesoscale to near synoptic scale do not significantly impact common mode dust size either. When combined with other APS observations around the world, the dust coarse mode is found to be fairly robust with a volume median diameter on the order of ∼3.5 μm ± 30%. Finally, evidence for a strong submicron dust mode, suggested in previous studies, was inconclusive.