Measurement of atmospheric optical parameters on US Atlantic coast sites, ships, and Bermuda during TARFOX

The Aerosol Robotic Network (AERONET) of automatic Sun/sky radiometers coll ected data on U.S. Atlantic coast sites, ships, and Bermuda in 1996 during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX ). Spatial and temporal analysis of Sun photometry data was supported by sy noptic analysis of air mass evolution. The spatial distribution of aerosol optical depth is presented. In several cases the aerosol size distributions deduced from sky almucantar measurements and solar disk attenuation measur ements at the various coastal sites yielded similar results within the same air masses. Ship-based measurements in the Atlantic Ocean showed significa nt maritime aerosol optical property variations which for the most part cou ld be attributed to the influence of continental sources and Saharan dust e vents. The Bermuda data (optical depths and;Angstrom parameter values) illu strated changes in atmospheric optical properties for various air masses an d trajectories. Almost no correlation was observed between aerosol optical depth and water vapor content when the data from all stations and ship meas urements were considered together. In the case of individual stations or sh ip transects, different degrees of correlation could be observed. In contin ental conditions on the east coast, optical depth and water vapor are well correlated, while in a maritime environment, optical depth can be relativel y small despite high water vapor contents.