Closeout Report, NAGW-5186 (previously -4088, -4807)

February 26, 1999

PROPOSAL TITLE: Contribution of Volcanic Activity to the Atmospheric Sulfur Dioxide Budget

PRINCIPLE INVESTIGATOR: Gregg J.S. Bluth, Michigan Technological University

Project summary

In this research project we have been investigating the volcanic contribution to the global sulfur budget using data from the Total Ozone Mapping Spectrometer (TOMS). The objectives were threefold: to validate SO 2 retrievals using TOMS, particularly for clouds at tropospheric altitudes; to develop techniques to use the TOMS data for studying physical and chemical evolution of SO2 clouds; and to evaluate the emissions of sulfur from global volcanic activity to the troposphere.

During the course of this research project I relocated from Goddard to University of Maryland (1993-94), and Michigan Tech (MTU; 1994-present). The net result is a signficant expansion of our original group at Goddard into a close working relationship between the Goddard TOMS SO2 group and a number of faculty and student researchers at MTU. This project has provided advisorial and/or direct support five different graduate students in remote sensing studies of volcanic clouds: Heather Shocker (M.S. 1997), who completed an internship at Goddard with the TOMS group during the Fall of 1995; Jeremy Shannon (M.S. 1997), who completed a similar internship during the Spring of 1996; Emily Constantine (M.S. 1998) with an internship in 1997); Colleen Riley (Ph.D., in progress); and Sharon Barker (Ph.D., in progress). Our MTU-Goddard collaborations have produced some outstanding work in satellite sensing of volcanoes (as noted below and in Tables 1 and 2). The Ph.D. student publications are not listed here because this work falls under subsequent grants.

Research performed under this proposal has been used in eleven peer-reviewed publications (four by the PI as first author;Table 1), and eighteen presentations at national or international meetings (Table 2). Over 80 citations for these publications have been recorded as of October 1998 (details in Table 3).

Validation of TOMS SO2 retrievals. Bluth et al. (1994) combined TOMS SO2 data with those of the COSPEC (a ground and/or aircraft based instrument) to estimate a sulfur emission budget for the series of eruptions of Galunggung, Indonesia in 1982-1983. The emission characteristics and measurement techniques of high-temperature volcanic gases were reviewed by myself and collaborators (Symonds et al., 1994), and we provided a model of the timing, vent characteristics, sampling methods and expected results for an idealized eruption sequence of Mt. St. Helens. A major effort by the TOMS research group at Goddard was to complete a full description of the TOMS technique, with a discussion of potential errors and appropriate applications of the data (Krueger et al., 1995).

Physical and chemical fate of volcanic clouds. We studied the 1982-1983 eruptions of Mt. Galunggung (Bluth et al., 1994) using the dispersion rates of the SO2 clouds, altitude estimates of co-emitted ash clouds, and comparison of cloud motion to tropospheric winds to determine the tropospheric component of the approximately 2.5 Mt of emitted SO2. Likewise, we analyzed the TOMS and other data for the three main eruptions of Mount Spurr, Alaska during 1992 (Bluth et al., 1995) and estimated the stratospheric versus tropospheric emplacement of the SO2 clouds. The 1994 eruption of Rabaul was examined by combining efforts from research groups at Michigan Tech and Goddard, and different satellite instruments towards the common goal of understanding volcanic eruption clouds (Rose et al., 1995). We identified significant quantities of ice in the eruption cloud (seen through AVHRR) and low SO2 (measured by TOMS), indicating that SO2 was scavenged through entrainment of seawater in the eruption column.

Global volcanism. Bluth et al. (1993) used the TOMS data to estimate a total SO2 flux from explosive volcanism of approximately 4 Mt/yr. Of the total annual volcanic output, the TOMS data suggest that on average only 2.5 Mt are injected into the stratosphere. A major uncertainty in a tropospheric estimate are the small explosive eruptions which cannot be or are rarely seen by TOMS; it is here where a correlation between SO2 emission and explosivity (VEI) is most critical. Together with David Pyle and Paul Beattie (Pyle et al., 1996), we attempted to differentiate stratospheric from tropospheric volcanic emissions by creating statistical relationships between VEI and TOMS SO2 data. The statistical relationship is hampered by the small number of eruptions available, and that the few very large eruptions tend to dominate the global SO2 budget.

Sulfur loading. Bluth et al. (1997) used the TOMS data to estimate the potential sulfur aerosol loading into the atmosphere by combining the TOMS SO2 1979-1994 database, estimates of SO 2 conversion to aerosol, and subsequent aerosol removal rates (preliminary work was presented at the 1995 AGU meeting; Bluth et al., 1995). Compared to the aerosol optical depth record, our model demonstrates a close approximation of actual conditions for the two largest eruptions (El Chichón and Pinatubo), but a poor correlation for the smaller eruptions. The results suggest a kind of threshold for volcano/atmosphere interaction where eruption columns that reach heights of the tropopause or only slightly above are subject to (sometimes highly efficient) self removal mechanisms. In a related study by Schnetzler et al. (1997), we investigated the relationship between VEI and sulfur emission, as a framework by which to study the physical and chemical characteristics of volcanic eruptions.

Cloud lifetimes in the troposphere. The rates of SO 2 dispersion vary enormously for different eruptions clouds. In the literature, SO2 dispersion rates are not well known for large eruption clouds, largely due to the effects of mass and concentration effects on reaction rates. For example, we observed that the Pinatubo (stratospheric) cloud dispersed at roughly 10% per day, while Galunggung clouds (tropospheric) dispersed at rates of 50% or more per day; the three eruptions of Mt. Spurr in 1991 dispersed at intermediate rates. This work has led to the deveopment of thesis topics for two current Ph.D. students. Sharon Barker is evaluating approximately 20 eruptions in the TOMS database for which at least 4 days of data are available, to compare the dispersion rates for the various eruptions. Another Ph.D. student, Colleen Riley, is concentrating on the effect of ash particles on SO2 removal.

Combining satellite instrument datasets. Several graduate students have focused their efforts on case studies making direct comparisons of TOMS and AVHRR measurements of volcanic clouds (Table 1). Heather Shocker has been studying the Lascar eruption of 1993, comparing the masses, distribution and and evolution of the SO2 and ash clouds. Jeremy Shannon worked closely with the Goddard SO2 group and Paul Newman (Atmospheric Dynamics) to use wind trajectory models to constrain the altitudes and travel paths of the SO 2 and silicate ash clouds from the three eruptions of Mt. Spurr in 1992. Determination of cloud altitudes are crucial to understand as the retrieval algorithms for both ash and gas depend on assumptions of atmospheric influence, or essentially the thickness of the atmosphere between instrument and cloud. Emily Constantine combined TOMS and AVHRR observations of the drifting volcanic clouds from the August 1991 eruptions of Cerro Hudson in southern Chile. This study suggests a gravitational separation of ash and gas, resulting in sharply different residence times in the atmosphere for the two species.

Table 1. Publications Relevant to the Tropospheric Aerosols Project

Constantine, E. (1998) Remote sensing of the August, 1991 Cerro Hudson volcanic eruption clouds. M.S. Thesis, Michigan Technological University, 123 pp.

Bluth, G.J.S., W.I. Rose, I.E. Sprod, and A.J. Krueger (1997) Stratospheric loading from explosive volcanic eruptions. Journal of Geology , 105, 671-683.

Schnetzler, C.C., G.J.S.Bluth, A.J. Krueger, and L.S. Walter (1997) A proposed volcanic sulfur dioxide index (VSI). Journal of Geophysical Research , 102, 20,087-20,092.

Pyle, D.M., P.D. Beattie, and G.J.S. Bluth (1996) Sulphur emissions to the stratosphere from explosive volcanic eruptions. Bulletin of Volcanology , 57, 663-671.

Shannon, J. (1996) 3-D reconstruction of the Mt. Spurr volcanic clouds using AVHRR, TOMS, and wind trajectory data. M.S. Thesis, Michigan Technological University, 95 pp.

Shocker, H. (1996) Evolution of volcanic clouds from the 1993 Lascar Chile eruption.M.S. Thesis, Michigan Technological University, 67 pp.

Bluth, G.J.S., C.J. Scott, I.E. Sprod, C.C. Schnetzler, A.J. Krueger, and L.S. Walter (1995) Explosive SO2 emissions from the 1992 eruptions of Mount Spurr, Alaska. In, U.S. Geological Survey Bulletin 2139, The 1992 Eruptions of Crater Peak vent, Mount Spurr Volcano, Alaska (T.E.C. Keith, ed.), 37-45.

Krueger, A.J., L.S. Walter, P.K. Bhartia, C.C. Schnetzler, N.A. Krotkov, I. Sprod, and G.J.S. Bluth (1995) Volcanic sulfur dioxide measurements from the Total Ozone Mapping Spectrometer (TOMS) instruments. Journal of Geophysical Research, v. 100, 14,057-14,076.

Rose, W.I., D.J. Delene, D.J. Schneider, G.J.S. Bluth, A.J. Krueger, I. Sprod, C. McKee, H.L. Davies, G.G.J. Ernst (1995) Ice in Rabaul eruption cloud of 19-21 September 1994. Nature, v. 375, 477-479.

Schnetzler, C.C., A.J. Krueger, G.J.S. Bluth, I.E. Sprod, and L.S. Walter (1995) Comment on the paper "The atmospheric SO2 budget for Pinatubo derived from NOAA-11 SBUV/2 spectral data" by R.D. McPeters. Geophysical Research Letters, v. 22, 315-316.

Symonds, R.B., W.I. Rose, G.J.S. Bluth, and T.M. Gerlach (1994) Volcanic-gas studies: Methods, results, and applications. In, Volatiles in Magmas (M.R. Carroll and J.R. Holloway, eds.), Reviews in Mineralogy, v. 30, 1-60.

Krueger, A.J., S.D. Doiron, G.J.S. Bluth, L.S. Walter, and C.C. Schnetzler (1994) Volcanic hazard detection with the Total Ozone Mapping Spectrometer (TOMS). U.S. Geological Survey Bulletin 2047 (T.J. Casadevall, ed.), Volcanic Ash and Aviation Safety: Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety, 367-372.

Bluth, G.J.S., T.J. Casadevall, C.C. Schnetzler, S.D. Doiron, L.S. Walter, A.J. Krueger, and M. Badruddin (1994) Evaluation of sulfur dioxide emissions from explosive volcanism: the 1982-1983 eruptions of Galunggung, Java, Indonesia. Journal of Volcanology and Geothermal Research, v. 63 , 243-256.

Bluth, G.J.S., C.C. Schnetzler, A.J. Krueger, and L.S. Walter (1993) The contribution of explosive volcanism to global atmospheric sulphur dioxide concentrations. Nature, v. 366, 327-329.

Table 2. Presentations Relevant to the Tropospheric Aerosols Project

Cookman, B.E., G.J.S. Bluth, and C.J. Seftor (1997) An on-line tutorial for TOMS SO2, ash, and aerosol analyses. Eos Transactions AGU.

Constantine, E., W.I. Rose, and G.J.S. Bluth (1997) Remote sensing of the 1991 volcanic clouds from Cerro Hudson volcano, Chile. Eos Transactions AGU.

Rose, W.I., and G.J.S. Bluth (1997) Volcanic cloud/atmosphere interactions: The first week. GSA Abstracts with Programs, v. 29, No. 6.

Bluth, G.J.S., W.I. Rose, I.E. Sprod, and A.J. Krueger (1997) Stratospheric loading of sulfur from explosive volcanic eruptions. IAVCEI 97 General Assembly, Puerto Vallarta, Mexico, Jan. 20-24, p. 19.

Shannon, J.M., Bluth, G.J.S., and Rose, W.I. (1997) Evaluating 3-D dispersion of volcanic plumes using TOMS, AVHRR, and wind trajectories. IAVCEI 97 General Assembly, Puerto Vallarta, Mexico, Jan. 20-24, p. 20.

Bluth, G.J.S., I.E. Sprod, A.J. Krueger, C.C. Schnetzler, and L.S. Walter (1995) Atmospheric loading of sulfur from explosive volcanic eruptions. Eos Transactions AGU, v. 76, F659.

Schneider, D.J., W.I. Rose, G.J.S. Bluth, A.J. Krueger, and I. Sprod (1995) Observations of the separation of volcanic ash and sulfur dioxide in the April 4-6, 1982 El Chichon volcanic cloud using AVHRR and TOMS. Eos Transactions AGU, v. 76, F659.

Shannon, J.M., G.J.S. Bluth, and K.G. Dean (1995) A meteorological display for evaluating trajectories and altitudes of drifting volcanic clouds. Eos Transactions AGU, v. 76, F659.

Shocker, H.L., G.J.S. Bluth, W.I. Rose, A.J. Krueger, P.A. Newman, I.E. Sprod, N.A. Krotkov, and J. Viramonte (1995) Analysis of the April 19-22 1993 eruption of Lascar, Chile using TOMS, AVHRR and HIRS/2. Eos Transactions AGU.

Rose, W.I., D.J. Schneider, and G.J.S. Bluth (1995) Mitigating hazards of drifting volcanic clouds using satellite data. IUGG XXI General Assembly meeting, July 1995, Boulder, CO.

Shocker, H.L., D.J. Schneider, G.J.S. Bluth, W.I. Rose, A.J. Krueger, and I.E. Sprod (1995) Analysis of the Mount Pinatubo volcanic cloud using AVHRR and TOMS. IUGG XXI General Assembly meeting, July 1995, Boulder, CO.

Bluth, G.J.S. (1994) Remote sensing of volcanic emissions. Mineralogical Society of America Short Course on Volatiles in Magmas, December 2-4, 1994, Napa, CA.

Sprod, I.E., A.J. Krueger, G.J.S. Bluth, N. Krotkov, C.C. Schnetzler, and L. Walter (1994) Evaluation of Meteor-3 TOMS observations of volcanic SO2 clouds. Eos Transactions AGU, v. 75, 125.

Shannon, J. M., and G.J.S. Bluth (1994) Volcanic cloud dispersion: a study of SO2 emissions from the 1980 eruptions of Mount St. Helens. Eos Transactions AGU, v. 75, 716.

Bluth, G.J.S., C.C. Schnetzler, A.J. Krueger, L.S. Walter, and I.E. Sprod (1993) Annual volcanic emissions of sulfur dioxide to the atmosphere. Eos Transactions AGU, v. 74, 683.

Krueger, A.J., L. Walter, G. Bluth, and C. Schnetzler (1993) Tectonic settings and volcano-climate effects. Eos Transactions AGU, v. 74, 105.

Sprod, I.E., G.J.S. Bluth, A.J. Krueger, L.S. Walter, and C.C. Schnetzler (1993) Comparison of TOMS SO2 data from El Chichón and Mount Pinatubo eruptions. Eos Transactions AGU, v. 74, 132.

Walter, L.S., G.J.S. Bluth, C.C. Schnetzler, I.E. Sprod, and A.J. Krueger (1993) Satellite observation of SO2 emissions from the 1984 Mauna Loa eruption. Eos Transactions AGU, v. 74, 636.

Table 3. Citations of published papers (from those listed in Table 1)

Number of Citations

Publication

1994

1995

1996

1997

1998*

Total

Bluth et al., 1997

2

2

Pyle et al., 1996

3

1

1

5

Bluth et al., 1995

1

2

1

4

Krueger et al., 1995

4

9

2

15

Rose et al., 1995

3

1

4

Symonds et al., 1994

1

3

5

9

18

Bluth et al., 1994

1

1

2

Bluth et al., 1993

5

8

4

9

6

32

Total

5

9

19

30

19

82

*as of October 1998