Optical Extinction Predictions from Measurements Aboard a British Weather Ship

摘要

The Admiral Fitzroy is one of two weather ships that tend station Lima, 57 deg N 20 deg W, for the British Ocean Weather Service. We were aboard Fitzroy on station over a twenty-day period in the month of July. Using two Particle Measuring Systems (PMS) particle spectrometers, we measured marine aerosols with radii in the size range from 0.1 to 15 micrometers. The probes were 3 m from the ocean surface on the windward quarter of the drifting ship. The aerosol size distributions gave calculated extinction coefficients at ten wavelengths between 0.4 and 10.0 micrometers. Statistical plots show the most frequent aerosol extinction to be near 0.02/km for 0.55 micrometer and 0.005 km for 10.0 micrometers. A plot of calculated extinction versus wavelength for several conditions shows that the ratio for extinctions, k0.55/k10.0 , cannot be considered to be constant. (Author)