Calculating the Height of Volcanic Cloud SO2 With a Lagrangian Trajectory Tool: Raikoke (2019) and Pinatubo (1991) Cases

Abstract:

We have developed a new data analysis tool to reconstruct the altitude of SO₂ clouds ejected by a volcanic eruption. Starting with 2D fields of satellite observed SO₂ column density, known volcano location, and reanalysis wind fields, the Goddard Lagrangian trajectory tool allows us to estimate the altitude and local concentration of SO₂ at the time of observation. We demonstrate this tool for the June 21, 2019 Mt. Raikoke eruption (8h, 30h and 78 hours after eruption). We use SO₂ data from the Ozone Mapping and Profiler Suite/Nadir Mapper (OMPS/NM) onboard the NASA-NOAA Suomi National Polar Partnership satellite and the Tropospheric Monitoring Instrument (TROPOMI) onboard the European Copernicus Sentinel 5 precursor satellite and wind fields from the NASA Goddard Earth Observing System (GEOS) model. We obtained a wide distribution of SO₂ altitudes between 1 and 19 kilometers in different parts of the Raikoke SO₂ clouds, with the highest SO₂ concentration between 11 and 16 km, in good agreement with data from independent SO₂ layer height retrievals from TROPOMI and Infrared Atmospheric Sounding Interferometer (IASI). We then applied this method to the June 15, 1991 Mt. Pinatubo eruption using SO₂ column measurements from the NASA Total Ozone Mapping Spectrometer (TOMS) on June 16, 17, 18 and using wind fields from the National Centers for Environmental Prediction Reanalysis version 2. We obtained a wide distribution of SO₂ heights from 6 km up to 30 km in the northern part of the cloud. We use our new trajectory tool to reconstruct volcanic SO₂/aerosol emission sources as functions of time and altitude, providing inputs to the GEOS model aerosol and chemistry schemes in order to simulate the dispersion of volcanic SO₂ and aerosol clouds from these events.