Satellite-derived sulfur dioxide (SO2) emissions from the 2014–2015 Holuhraun eruption (Iceland)

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Carboni, Elisa, Mather, Tamsin A., Schmidt, Anja, Grainger, Roy G., Pfeffer, Melissa A., Ialongo, Iolanda, Theys, Nicolas
• Format: Text
• Language: English
• Published: 2019
• Subjects: Holuhraun; Iceland
• Online Access: https://doi.org/10.5194/acp-19-4851-2019; https://www.atmos-chem-phys.net/19/4851/2019/

The 6-month-long 2014–2015 Holuhraun eruption was the largest in Iceland for 200 years, emitting huge quantities of sulfur dioxide ( SO 2 ) into the troposphere, at times overwhelming European anthropogenic emissions. Weather, terrain and latitude made continuous ground-based or UV satellite sensor measurements challenging. Infrared Atmospheric Sounding Interferometer (IASI) data are used to derive the first time series of daily SO 2 mass present in the atmosphere and its vertical distribution over the entire eruption period. A new optimal estimation scheme is used to calculate daily SO 2 fluxes and average e -folding time every 12 h. For the 6 months studied, the SO 2 flux was observed to be up to 200 kt day −1 and the minimum total SO 2 erupted mass was 4.4±0.8 Tg. The average SO 2 e -folding time was 2.4±0.6 days. Where comparisons are possible, these results broadly agree with ground-based near-source measurements, independent remote-sensing data and values obtained from model simulations from a previous paper. The results highlight the importance of using high-resolution time series data to accurately estimate volcanic SO 2 emissions. The SO 2 mass missed due to thermal contrast is estimated to be of the order of 3 % of the total emission when compared to measurements by the Ozone Monitoring Instrument. A statistical correction for cloud based on the AVHRR cloud-CCI data set suggested that the SO 2 mass missed due to cloud cover could be significant, up to a factor of 2 for the plume within the first kilometre from the vent. Applying this correction results in a total erupted mass of 6.7±0.4 Tg and little change in average e -folding time. The data set derived can be used for comparisons to other ground- and satellite-based measurements and to petrological estimates of the SO 2 flux. It could also be used to initialise climate model simulations, helping to better quantify the environmental and climatic impacts of future Icelandic fissure eruptions and simulations of past large-scale flood lava eruptions.