High-resolution simulation of volcanic sulfur dioxide dispersion over the Miyake Island

• Published in: Atmospheric environment (1994) Vol. 38; no. 40; pp. 7073 - 7081
• Main Authors: Seino, Naoko, Sasaki, Hidetaka, Sato, Junji, Chiba, Masaru
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2004; Elsevier Science
• Subjects: Applied sciences; Atmospheric pollution; Dispersion model; Exact sciences and technology; Multi-nesting; Nonhydrostatic model; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Volcanic SO 2; West Pacific; Asia; Honshu; Japan; Pacific Ocean; Miyake Jima; Izu-sichito; Nonhydrostatic model; Multi-nesting; Dispersion model; Volcanic SO 2; Atmospheric condition; High resolution; Wind field; Marine atmosphere; Pollutant behavior; Troposphere; Turbulent diffusion; Time variation; Sulfur dioxide; Transport process; Random walk model; Volcanic SO2; Pollution source; Geogenic factor; Air pollution; Numerical simulation; Atmospheric dispersion; Lagrangian method; Volcanism; Surface wind; Concentration distribution
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2004.01.061

After severe eruptions of the volcano at Miyake Island in August 2000, a large amount of volcanic gas was released into the atmosphere. To simulate flows and dispersion of sulfur dioxide (SO 2) over Miyake Island, a set of numerical models was developed. The multi-nesting method was adopted to reflect a realistic meteorological field and to sufficiently resolve the flow over the island with a diameter of 8 km. The outermost model was the Regional Spectral Model (RSM) of the Japan Meteorological Agency (JMA) with a horizontal grid size of 10 km. Finer atmospheric structure was simulated with the nonhydrostatic model jointly developed by the Meteorological Research Institute and the Numerical Prediction Division of JMA (MRI/NPD-NHM) with grid intervals of 2 km, 400 m and 100 m. Realistic topography of the island was represented in the innermost model. The Lagrangian particle method was applied to the dispersion model, which is driven by the meteorological field of the 100 m grid MRI/NPD-NHM. The random walk procedure was used to represent the turbulent diffusion. The model was verified in four cases. Simulated SO 2 concentrations agreed well with observed concentrations at a monitoring station including temporal variation. Under a large synoptic change, however, accurate prediction became difficult. Further numerical experiments have been done to investigate characteristics of the flow and the distribution of SO 2. Steady inflows, classified according to the surface wind speed and direction, were assumed. Simulated SO 2 distribution on the ground apparently depends on the surface wind. Under relatively weak inflow, there is a large diurnal change in SO 2 distribution, affected by the thermally induced flow. SO 2 gas is widely spread downstream in the nighttime but hardly reaches the coastal area in the daytime. On the other hand, SO 2 gas steadily reached the downstream coast with little diurnal variation under the stronger inflow. Ground temperature, as well as the static stability of the inflow, also influences downstream wind, turbulent diffusivity and SO 2 distribution.