Wintertime observations of tropical Northwest Atlantic aerosol properties during ATOMIC: Varying mixtures of dust and biomass burning

Measurements of aerosol chemical, microphysical, optical, and cloud-nucleating properties were made during boreal winter onboard the NOAA RV Ronald H. Brown from 7 January to 13 February 2020.

Observed aerosol properties indicate there were distinct periods when the aerosol was typical of clean marine conditions (particle number concentrations <400 cm(-3), light absorption levels <1 Mm(-1), and Rn-222 concentrations <500 mBq m(-3)) and when there were intrusions of dust mixed to varying degrees with biomass burning aerosol. In comparison to the long-term dust record at the Barbados Atmospheric Chemistry Observatory, the fraction of samples collected during ATOMIC with dust concentrations greater than 20 mu g m(-3) exceeded all years of the Barbados January to February record with the exception of 1983.