Special issue  

Wind-borne mineral dust can affect climate through its interaction with radiation and its role in cloud microphysical processes. In spite of this importance, there has been little research on the long-range transport of mineral dust. In particular critical understanding of the transformations of mineral dust during long-range transport including changes in physical and chemical properties of the particles and the roles of various removal processes during transport is lacking. In addition, climate change threatens to change dust emission rates and hence future dust impacts.

To investigate the long-range transport of mineral dust from the Sahara into the Caribbean, and to study the impact of aged mineral dust on both the radiation budget and cloud microphysical processes, the Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE, http://www.pa.op.dlr.de/saltrace/ ) was conducted in June/July 2013. During SALTRACE, mineral dust from several dust outbreaks was studied under a variety of atmospheric conditions, and a comprehensive data set on chemical, microphysical and optical properties of aged mineral dust was gathered.

SALTRACE was a German initiative involving scientists from Europe, Cabo Verde , the Caribbean and the US. It was designed as a closure experiment combining ground-based, airborne, satellite and modelling efforts. Ground-based lidar, in situ aerosol and sun photometer instruments were deployed on Barbados (main SALTRACE super-site), Cabo Verde and Puerto Rico. The DLR research aircraft Falcon carried an extensive suite of in situ and remote-sensing instruments and spent more than 110 flight hours studying the long-range transport of mineral dust between Senegal, Cabo Verde, the Caribbean and Florida.

SALTRACE was highly successful and allowed the collection of a unique mineral dust data set which will be presented in this SI, including papers on the experimental, theoretical, and modelling results, as well as instrument and algorithm developments related to the SALTRACE field experiment.