Detection of volcanic SO₂ in the North Pacific Region using ASTER and MODIS

Abstract

This study investigates the detection of volcanic SO₂ using TIR satellite-based and UV ground-based measurements at volcanoes in the North Pacific during eruptions and low level degassing. The ASTER and MODIS sensors with spatial resolutions of 0.09 and 1.0 km, respectively, are used to quantify SO₂ from the 8.6 um absorption feature of the gas species. Three volcanoes within this region were studied: Mt. Cleveland to test the implementation of the MAP ̲SO2 software, Bezymianny to determine the sensitivity of the algorithm to input parameters during eruption conditions, and Shishaldin to evaluate the detection of SO₂ during low level degassing. Total SO₂ estimates from the January 2004 Bezymianny eruption range from 15.5 kt to 87.2 kt at 0210 UTC depending on the input parameters. An emission rate of 0.295 kt·min⁻¹ and transport rate of 16.6 m·s⁻¹ were estimated from time sequential MODIS passes. SO₂ flux estimates at Shishaldin Volcano on 26 May 2004 were 164 t·day⁻¹ from ASTER and 58 t·day⁻¹ on 31 July 2004 from MUSe. The data show that SO₂ during low level degassing and eruptive conditions can be detected in the region and the sensors from this study provide a detection continuum from low to high SO₂ concentrations.