Simulated impacts of SO2 emissions from the Miyake volcano on concentration and deposition of sulfur oxides in September and October of 2000

A regional air quality Eulerian model was run for 2 months (September and October of 2000) with and without SO2 emissions from the Miyake volcano to investigate effects of the changes in the volcanic emissions on SO2 and sulfate concentrations and total sulfur deposition around the surrounding areas. Volcanic emissions were injected into different model layers in different proportions within the planetary boundary layer whereas the other emissions were released in the first model layer above the ground. Meteorological fields four times per day were taken from National Centers for Environmental Prediction (NCEP). Eight Japanese monitoring sites of EANET (Acid Deposition Monitoring Network in East Asia) were used for the model evaluation. Simulations indicate that emissions from the Miyake volcano lead to increases in SO2 and sulfate concentrations in the surrounding areas downwind in the PBL by up to 300% and 150%, respectively, and those in SO2 levels in the area found 390 km north away from the Miyake site in the free troposphere (FTR) by up to 120%. Total sulfur deposition amounts per month are also increased by up to 300%. Daily SO2 concentrations in different model layers display strong variability (10–450%) at sites significantly influenced by the volcano. Comparison shows that the RAQM model predicts daily SO2 variations at relatively clean sites better than those at inland sites closer to volcanoes and the model well captures the timing of SO2 peaks caused by great changes in SO2 emissions from the Miyake volcano at most chosen sites and that monthly simulated sulfate concentrations in rainwater agree quite well with observations with the difference within a factor of 2. Improvement in spatial and temporal resolutions of meteorological data and removal of the uncertainty of other volcanic emissions may better simulations.