Black Carbon and Particulate Matter Emission Factors from Ships Encountered During CalNex

Light absorption and light extinction measurements made aboard the NOAA-sponsored R/V Atlantis during the CalNex campaign were used to derive black carbon (BC) and total sub-micron particulate matter (PM) mass emission factors (EFs) from ships in operation along the California coast. Light absorption measurements were made using a photoacoustic spectrometer (PAS) at 532 nm and 405 nm and a three wavelength particle soot absorption photometer (PSAP) at 450, 530 and 700 nm. Light extinction measurements were made at 532 nm using a cavity ringdown spectrometer. Absorption and extinction measurements were converted to mass-based EFs using wavelength-specific absorption or extinction coefficients. Emission factors were binned according to ship type classifications and engine type classifications, and they were considered as a function of estimated engine load. Campaign average EFs were also derived. There were no discernable trends for EFs as a function of engine load. In comparison to the EFs measured during TexAQS by Lack et al., the CalNex EFs, for the campaign average and for the specific ship and engine type classifications, were overall lower. This difference between the TexAQS and CalNex EF values may be attributable to the required use of lower sulfur fuel by ships in California coastal waters.