A four-year record of simultaneously measured aerosol chemical and optical properties at a marine site in northern California

Between April 2002 and June 2017, the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Laboratory (GML) made continuous measurements of a suite of in-situ aerosol optical properties (AOPs) at a monitoring site near Trinidad Head (THD), California. The AOPs included total aerosol light scattering and hemispheric back-scattering coefficients, aerosol light absorption coefficients. The condensation nuclei concentration (CN) was also measured. A scanning humidograph system operated at the site between 2002-2006 and provided humidity-dependent light scattering measurements from which the scattering enhancement factor (f(RH)) could be determined. Additionally, inorganic ion and total aerosol mass concentrations were obtained from filter measurements for the first 4 years of the program. An AERONET sunphotometer provided column measurements of aerosol properties at the site between 2005 and 2017.

We report temporal cycles of the observed aerosol chemical and optical properties and then present statistical relationships between the AOPs and chemical composition in order to identify natural and anthropogenic sources impacting the aerosol radiative properties. Combined analysis of these datasets suggests that while THD aerosol optical and chemical properties are generally comparable to those reported for other clean marine sites described in the literature, local anthropogenic sources (e.g., wintertime home heating, vehicular and marine traffic) impact the site. This dataset may be particularly useful for model evaluation due to the long-term collocation of surface in-situ aerosol optical and chemical measurements and column aerosol optical property retrievals.