The production and dispersal of marine aerosol

Abstract

This paper describes an extensive series of aerosol experiments conducted from a coastal site on the island of South Uist in the Outer Hebrides. Measurements at this site are shown to be reasonably representative of open ocean conditions. Aerosol size distributions (0.08 < radius, r, < 23.5 m̈m) and basic meteorological parameters were measured under both continental and maritime conditions. In all cases wind speed was found to have a dominant effect on aerosol characteristics; the volumetric loading, V(m̈m3 cm−3), increased rapidly with wind speed U(ms−1) according to ln(V) = bU + A, where, for the larger aerosol b ≈ 0.2 sm−1 and A ≈ 4. the size distributions could be principally divided into two ranges at r ≈ 0.5 m̈m, the lower corresponding to long-range aerosol and the higher to particles produced locally, by bubble bursting at the sea surface. Results of the S. Uist experiments are compared with each other and with those of other workers. Other findings include a general but not exclusive insensitivity of aerosol characteristics to the range of relative humidity experienced at S. Uist; a decrease of aerosol concentrations, n, with altitude; and an inverse relationship between n and mixing height.