Research
Our research uses remotely sensed data of volcanic emissions to shed light on problems within five fields. These are: (1) subsurface processing and volcanic activity, (2) plume fliud dynamics, (3) hazards to aviation (4) plume chemisty and (5) environmental and climate effects.
The group can be divided into three distinct subgroups. These can be related to the spatial scale at which the measurements are made, and in increasing scale are:
(i) Ground-based measurements of emission rates using electrochemical sensors and closed and open path differential optical absorption spectroscopy (DOAS).
(ii) Development, testing and deployment of a new ultraviolet imaging camera.
(iii) Multi-species algorithm development for NASA's IR sensors ASTER, MODIS and AIRS.
We hope to use these tools to address six key issues in volcano remote sensing:
(i)What are the environmental factors effecting SO2 loss rates? A PhD student (Lizzette Rodriguez) has investigating this question using a combination of ground based techniques (Sun-photometry, DOAS and UV Camera) and satellite imagery (ASTER, MODIS).
(ii)How do gas emission rates vary on short (less than one hour) timescales and can changes immediately before explosions be quantified? Two Ph.D students (Yvonne Branan and Peter Holland) have contributed to working on comparing high temporal resolution DOAS data and comparing it to seismic data to elucidate subsurface processes.
(iii)How can current satellite-based retrievals be improved to deal with the spectral interaction of multiple species? Single-species algorithms are currently applied to AVHRR, GOES, and MODIS data, in order to mitigate aviation hazard and quantify volcanic emissions to the atmosphere on a global scale. The group have had five PhD students focused on the problem of developing multi-species retrievals (Alex Matiella-Novak, Emily McCarthy, Lorna Henney, Helen Thomas and Courtney Kearney) through a NASA algorithm development grant.
(iv)How can aviation hazard be more effectively mitigated. Specifically, how can the effects of water vapour variation upon the split-window retrieval be accounted for? We are developing an empirical atmospheric correction for ash maps based upon radiative transfer code to correct for water vapour in temperature difference maps. This will be useable in near-real time to enable more accurate tracking of ash by VAACs, specifically in tropical regions.
(v)Application of new technologies to improving volcanic gas emissions studies. Through development of real-time SO2 monitoring using UV sensitive focal-plane array cameras, we intend to provide volcano observatories with real-time images of SO2 gas plumes to advance monitoring using change in gas emission rates. The new instrument complements recent improvements in gas monitoring, such as the DOAS system. There is currently a Ph.D student (Peter Holland) working on this problem.
(vi) How can we get data to users in a timely manner? The group is involved in a multi-centre proposal to deliver science products to volcano observatories in near real-time. This is the ASTER Urgent Request Protocol (NASA) continuation project and is part of Helen Thomas's remit.
