Assessment of cruise–ship activity influences on emissions, air quality, and visibility in Glacier Bay National Park

An activity–based emission model was developed to determine cruise–ship emissions. Calculated emissions depend on cruise–voyage data (position, cruise speed, operation mode) and the ships’ characteristics (engine power, size, fuel– type, maximum cruise–speed). Cruise–ship emissions of particulate matter (PM) and its precursors were determined for the 2008 cruise season and for two proposed management actions: a prescribed speed in Glacier Bay, and implementation of an Emission Control Area (ECA) in Alaska at–large. The Weather Research and Forecasting model inline coupled with chemistry served to assess the impact of these management actions on air quality and visibility. On season–average, ships emitted ~2.5 µg/m2/s PM in Glacier Bay. Cruising at constant 6.69 m/s anywhere in Glacier Bay decreased PM–emissions by 32% and marginally increased mean visibility. Altered cruise speeds strongly changed the spatial emission and concentration distributions of all species in and up to 30 km downwind of Glacier Bay. Changes differed among species. An ECA reduced PM–emissions from cruise ships by 74% and their impacts on visibility by 0.1, 0.2 and 0.1 deciview for the 10%, 50% and 90%–percentiles of best–visibility–days in Glacier Bay.