Transport of radioactive aerosols across the trade wind inversion at Hawaii

Abstract

Radioactivity concentration measurements in aerosol and precipitation samples collected along the slopes of Mauna Loa volcano in Hawaii have been examined in relation to vertical profiles of temperature and humidity in the atmosphere across the trade wind inversion. The gradient of radioactive aerosol concentration in the air with height is related to the humidity profile and the character of the trade wind inversion. The concentrations increased with height across the trade wind inversion in contrast to aerosols of terrestrial origin whose concentrations in air decreased with height. The concentrations in rainfall generally decreased with height, except for an anomolous result at 2250 m, just below the trade wind inversion. At this altitude, the gross radioactivity concentration increased while the Sr90 concentration decreased. The ratio of the gross beta concentration in air and rain gives a parameter with dimensions of mixing ratio, which may be of potential use in determining rainout efficiencies.