Aerosol cations at mauna loa observatory

Aerosol and precipitation samples collected 3.4 km above sea level on the Island of Hawaii have only 1% of the concentrations of Na that samples collected at sea level have. This difference suggests a short residence time for marine aerosols moving up the slopes of Mauna Loa. The major increase in the bulk chemistry of K, Ca, and Mg relative to Na occurs during the rapid loss of the first 90% of the aerosol mass. The chemistry of the remaining ‘fractionated’ aerosols resembles that of Hawaiian rain. A second population of aerosols, with substantially lower Na concentrations than fractionated marine aerosols, is present above the trade wind inversion. The major cation chemistry of these aerosols resembles that of continental rain.