In-situ aircraft observations of the 2000 Mt. Hekla volcanic cloud: Composition and chemical evolution in the Arctic lower stratosphere

摘要: Abstract An instrumented NASA aircraft made comprehensive, in-situ measurements of trace gas concentrations and aerosol properties while flying through the eruptive cloud from Mt. Hekla in February March, 2000. The data reveal novel aspects evolution volcanic lower arctic stratosphere. Thirty-five hours after initial, sub-Plinian explosion on 26, 2000, intersected at an altitude 11.3 km. SO2 exceeded 1 ppmv, but no H2S was observed. Large HF ∼50 ppbv were nearly equal to HCl concentration, same ratio halogen species adsorbed fallen ash. Although reactive nitrogen are rarely detected clouds, significant HNO3 3 above background measured. A bimodal size distribution with total number densities exceeding 8000 particles/cm3 volume 65 μm3/cm3 Approximately 1/3 fine particles non-volatile (volcanic ash) remaining 2/3 volatile (sulfate ice). highly structured clearly delineated boundaries. In 18-day period following initial eruption, increases SO2, sulfate aerosol, HCl, mixing ratios again detected. Analysis partitioning sulfur between phases these later encounters shows that rate oxidation sulfuric acid broadly consistent changing OH time vernal equinox.