Closeout Report: Volcanic Hazards Products for the Pacific Disaster Center


January 20, 2002



Jet Propulsion Laboratory (JPL) Contract #1212354


Michigan Technological University (MTU) Investigators:


Gregg Bluth, PI

William Rose, co-PI

Matthew Watson, Senior Personnel



Project Summary

The focus of our research has been the formation of the volcanic fog (vog) in the state of Hawai'i. Vog results from the conversion of sulfur dioxide (SO2) gas emitted from Kilauea Volcano into an aerosol of sulfuric acid droplets and particles. We have developed techniques to map volcanogenic SO2 plumes and sulfate aerosol clouds with thermal infrared (TIR) remote sensing. These mapping techniques are complementary to the routines developed at the University of Hawai'i by John Porter to map aerosols with visible and near infrared (VNIR) remote sensing. Mesoscale wind models, developed by Steve Businger at the University of Hawai'i, are used to predict the transportation of the vog. By combining the TIR and VNIR mapping techniques, our operational goal is to enable tracking of the formation of vog from the emission of SO2, through the conversion of SO2 gas to sulfate aerosols, to the transport of these aerosols from the volcanic vent to the rest of Hawai'i.


We will provide the PDC with operational versions of the TIR SO2 and sulfate mapping software, as well as instructions for the use of these tools. The tools will allow the PDC to track the formation and transport of vog, and thus predict the arrival and potential impact of the vog on population centers.


Project Results

We have been able to deliver, on schedule, version 1.0 of the plume_mapper software. A specific need arose that was not fully addressed in the initial version: the ability to be able to distinguish between sulfur dioxide and sulfate in the 8.6 µm channel. To this end the PDC code returns values related to the total S burden (as SO2 and SO4 absorb in this channel) rather than distinct values. Our final work, in collaboration with JPL, helped elucidate this problem, through specific test datasets (acquired for Hawai'i, Etna and Nyamuragira). To this end we have developed a forward model, allowing us to predict transmission spectra (and hence at-satellite radiances) for SO4 to enable distinction from the SO2 signal. In the future we hope to be able to distinguish SO2 from SO4 as the forward model results suggest the 9.6 µm channel is sensitive to SO4 but not SO2. O3 absorbs strongly in the channel, but it is hoped that corrections for atmospheric species (specifically water vapor) developed at JPL as part of the project can be applied to O3.


We were able to complete testing, modification and implementation of the SO2 mapping tool. This included a binning technique to cut the time required to process a multispectral TIR image into an SO2 map. The binning technique exploits redundancies in the data (i.e. pixels having the same radiance spectrum) to reduce the number of times radiative transfer models have to be run to estimate SO2 concentration. Processing times have been cut in half in most cases, although order of magnitude reductions in processing time can be achieved in cases where the plume is over a uniform background, such as open water or a forest canopy.


We have been routinely obtaining MODIS, AVHRR, and GOES data for algorithm development and validation. Work has also included determining the detection limits of the sulfate mapping procedure in a tropical atmosphere through sensitivity analysis. Using the science tool analogue of the mapping tool we have been able, for the first time, to quantify emissions of SO2 in the TIR from space. We have calculated tonnages for both the Hekla eruption, Iceland and the Cleveland eruption, Aleutian Islands.


The personnel involved in this final stage included Matt Watson, with support from the MTU department's system adminstrator. MTU has hired Matthew Watson, a graduate of Cambridge University (UK) as a Post-Doc. Dr. Watson is a protégé of Clive Oppenheimer and the late Peter Francis, two pioneers of remote sensing volcanology. Watson has considerable experience with photometric measurements of volcanic plumes, and has focused his work on the integration of the SO2 mapping procedure developed at JPL with the aerosol mapping procedure developed at MTU.


Relevant Publications/Presentations

Bluth, G.J.S., I.M. Watson, W.I. Rose, V.J. Realmuto, S. Carn, A.J. Krueger and L.R. Lait (2001) MODIS and TOMS retrievals of volcanic sulfur and ash emissions from Nyamuragira volcano. Eos Transactions AGU, 82, F1361-F1362.

Bluth, GJS, Watson, IM, Rose, WI, Realmuto,VJ, Carn, S, Krueger, AJ and LR Lait (2001) MODIS and TOMS retrievals of volcanic sulfur and ash emissions from recent volcanic activity. NASA TOMS Science Meeting, Greenbelt, MD, November 2.

Rose, W I and G C Mayberry (in press) Use of GOES thermal infrared imagery for eruption scale measurements, Soufrière Hills, Montserrat, submitted to Geophysical Research Letters.

Rose, W.I., G.J.S. Bluth, I.M. Watson, T.Yu, and Y. Gu (2001) Hekla's February 26, 2000 eruption as seen and measured from space using MODIS, TOMS and AVHRR. Eos Transactions AGU, 82, F1355.

Watson, I.M., V.J. Realmuto, W.I. Rose, G.J.S. Bluth, C. Bader, T. Yu, and Y. Gu (2001) Satellite remote sensing of volcanic clouds using the Moderate Resolution Imaging Spectroradiometer (MODIS). Eos Transactions AGU, 82, F1355-F1356.