Detection of the Dispersion and Residence of Volcanic SO2 and Sulfate Aerosol from Nabro in 2011

Continuous detection of dispersion and residence of volcanic plumes in troposphere and lower stratosphere is vitally important for improving the understanding on the role of volcano eruptions in climate change. We report a 3-month continuous detection of dispersion and residence of volcanic plumes in the troposphere and stratosphere generated from the volcanic SO2 erupted by Nabro in Eritrea on June 12th, 2011 observed by the OMI sensor. The background SO2 concentration of 3 different height layers in troposphere and lower stratosphere were estimated by the 3-year-average daily concentration of monthly SO2 in 2005, 2007 and 2013, when there were no large explosive volcanic eruptions occurring. We also traced the diffusion path and the concentration of volcanic SO2 for the first 3 months after Nabro's eruption, and detected the appearance and dissipation of sulfate aerosols, which is a product converted from volcanic SO2. The results show that after Nabro erupted on June 12th, the volcanic plumes spread to middle latitudes (30°N-60°N) of Northern Hemisphere and loading by westerly jet. The volcanic SO2 in middle troposphere layer (TRM) and lower troposphere layer (TRL) stopped eastward spreading, and dissipated over the western Pacific Ocean on June 23rd. On June 26th, the volcanic SO2 in upper troposphere and lower stratosphere (STL) reached Mexico in Central America, and almost encircled the low latitudes and parts of middle latitudes. On June 28th, the volcanic SO2 plume showed an even distribution in STL. 37 days after the eruption, the volcanic SO2 in STL encircled the Northern Hemisphere evenly, sulfate aerosols in STL largely covered the low and middle latitudes and the daily concentration of SO2 was still higher than the background value. One month after the eruption, the global mean daily concentration of SO2 dropped to the normal value, but the daily concentration of SO2 and sulfate aerosols in low latitudes remained high, and dissipated not earlier than 3 months after the eruption of Nabro.