Sun photometer and lidar measurements of the plume from the Hawaii Kilauea Volcano Pu'u O'o vent: Aerosol flux and SO2 lifetime

Aerosol optical depths and lidar measurements were obtained under the plume of Hawaii Kilauea Volcano on August 17, 2001, ∼9 km downwind from the erupting Pu'u O'o vent. Measured aerosol optical depths (at 500 nm) were between 0.2–0.4. Aerosol size distributions inverted from the spectral sun photometer measurements suggest the volcanic aerosol is present in the accumulation mode (0.1–0.5 micron diameter), which is consistent with past in situ optical counter measurements. The aerosol dry mass flux rate was calculated to be 53 Mg d⁻¹. The estimated SO₂ emission rate during the aerosol measurements was ∼1450 Mg d⁻¹. Assuming the sulfur emissions at Pu'u O'o vent are mainly SO₂ (not aerosol), this corresponds to a SO₂ half-life of 6.0 hours in the atmosphere.