Composite shiptrack characteristics

Abstract

Shiptracks (131) identified from Advanced Very High Resolution Radiometer (AVHRR) satellite images during the Monterey Area Ship track Experiment (MAST) are extracted and correlated with the ships that caused them. Composite plots and statistics of shiptrack environmental, radiative and physical properties are presented. The composite shiptrack is 296 km long, approximately 7.3 hours old, and averages 9 km wide. The head of the track has a separation distance from the ship of 16 km, and a separation time(ST) of 25 minutes. It forms in a ambient environment with a true wind of 15 kts and a low cloud reflectance in channel 3 (low 3) of 11%. The composite shiptrack has a low 3 equal to 14% and average Delta Percent Change channel 1 and 3 values of 7% and 37% respectively. Approximately 85% of the variability or 'noise' in shiptracks radiative signature is environmentally generated and occurs on the large eddy scale (1-25km). The data set was broken into subsets to isolate the effect of ship parameters on shiptrack characteristics. Variations in ship propulsion type (steam turbine verses diesel) and designed shaft power rating (kW size) produce shiptracks that are statistically different in length, width, age and reflectance. The dispersion characteristics of shiptracks were favorably compared to standard, long range dispersion relationships.