Satellite remote sensing of volcanic plumes

Thesis

Volcanic plumes are one of many hazards associated with eruptions. Monitoring helps to mitigate against their effects, understand their environmental and climatic impacts, and interpret volcanic activity. While ground-based measurements are valuable, field campaigns and ground-based instrument networks are expensive and not always viable. Satellite remote sensing is a cost-effective alternative and can be used to track the propagation of plumes as they travel away from the source. This thesis explores some of the ways in which the Infrared Atmospheric Sounding Interferometer (IASI) can be used for this purpose.

A method known as CO2 slicing, commonly used to obtain the altitude of meteorological clouds, was adapted for IASI to find the altitude of volcanic ash clouds. The technique was first tested on modelled data, before being successfully applied to scenes containing ash from the Eyjafjallajökull and Grímsvötn eruptions.

The second part of this thesis explores how IASI retrievals can be used to monitor volcanic emissions of sulphur dioxide (SO2). A linear retrieval was first applied globally to identify sources of SO2, including emissions from explosive eruptions, non-eruptive degassing and anthropogenic sources. Emissions were commonly identified in Ecuador and Kamchatka and these were explored further with an iterative retrieval which quantified the SO2 amount in each region. The trends observed with IASI were similar to those seen with the Ozone Monitoring Instrument (OMI), and at Tungurahua, good agreement was seen with ground-based flux measurements.

The final chapter builds on this research by systematically comparing the upwind and downwind mean column amounts obtained with a linear retrieval at 166 volcanoes. This highlights the strengths and weaknesses of the retrieval and reveals emission trends at some volcanoes; sometimes agreeing well with trends from OMI and in thermal emissions. This simple procedure demonstrates the utility of using IASI for observing changes in volcanic emissions.

Authors: Taylor, IA

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: volcanic ash; SO2; volcanic plumes; satellite remote sensing; IASI
• Subjects: Atmospheric physics; Remote sensing; Earth sciences; Volcanology