Saharan Dust Signature Characterization during AEROSE 2015

While Saharan dust outflows are known to influence global radiative forcing, there is uncertainty in its direct effects on climate due to the inhomogeneity and evolving composition. The compositional complexity of dust aerosols arises from variations in source region and atmospheric aging processes. Relative to this investigation, a dust signature is defined as a set of chemical, optical, and size distributional characteristics that distinguish a dust storm event. We hypothesize that there may be an identifiable signature from dust events based on source region that may have the potential to serve as a proxy for their radiative forcing effect.

The signatures of dust storms over the eastern North Atlantic were analyzed during the 2015 Aerosol Ocean Science Expedition (AEROSE) campaign conducted onboard the NOAA Ronald H. Brown. Dust signatures were identified using a combination of chemical and infrared (IR) spectral analysis. Mineralogical components were deduced by multivariate data analysis of metal concentrations using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) on dust filters that collected based on particle size. The ship-based Marine Atmospheric Emitted Radiance Interferometer (M-AERI) enabled IR analysis of the suspended mineral dust particulate. The USGS spectral library was used as a consolidation tool for the spectral and chemical datasets. Iron enrichment was a pivotal observation when contrasting various dust air masses sampled during the 2015 AEROSE cruise. Through a combination of dust signature characterization techniques, a foundation for evaluating radiative forcing assessments of dust on North Atlantic heat budgets may be established.