1. Comparison of OMI SO 2 Satellite Data with Airborne Measurements from the 2006 Fourpeaked Eruption Taryn M. Lopez University of Alaska Fairbanks May 2007

2. Projective Objectives 1.Compare Fourpeaked SO 2 emissions measured from gas flights with OMI derived SO 2 product 2.Evaluate OMI as a potential tool to be integrated into the existing AVO – Remote Sensing monitoring routine

3. Photo by Lanny Simpson on 9/17/06 Background

4. Fourpeaked Eruption, 2006 9/17/06 at 12:00 PM AKDT9/17/06 at 12:00 PM AKDT ash cloud detected at 6,000 m above sea levelash cloud detected at 6,000 m above sea level Prior to this, Fourpeaked was not classified as an active volcanoPrior to this, Fourpeaked was not classified as an active volcano Gas flights on 9/23/06 and 9/24/06 detected 2,000 + tonnes per day of SO 2Gas flights on 9/23/06 and 9/24/06 detected 2,000 + tonnes per day of SO 2 Degassing, small explosions, and variable seismic activity have continued since SeptemberDegassing, small explosions, and variable seismic activity have continued since September www.avo.alaska.edu

5. Fourpeaked Location Map for Fourpeaked Volcano

6. OMI Background/Specifications OMI = Ozone Monitoring InstrumentOMI = Ozone Monitoring Instrument Flown on the EOS-Aura SpacecraftFlown on the EOS-Aura Spacecraft Aura was launched on July 15, 2004Aura was launched on July 15, 2004 Daily global coverage (14 orbits)Daily global coverage (14 orbits) 2600 Km swath width2600 Km swath width 13 x 24 Km spatial resolution at nadir13 x 24 Km spatial resolution at nadir 3 sampling modes: Global, Spatial Zoom in, Spectral Zoom in3 sampling modes: Global, Spatial Zoom in, Spectral Zoom in Schobert et al., 2006

7. OMI Specifications Hyperspectral UV/VIS spectrometerHyperspectral UV/VIS spectrometer Measures solar backscatter radiationMeasures solar backscatter radiation Uses non-scanning, wide-angle, nadir pointing, push-broom, imaging spectrographUses non-scanning, wide-angle, nadir pointing, push-broom, imaging spectrograph 1560 wavelength bands from 270-500 nm with a spectral resolution of 0.5 nm1560 wavelength bands from 270-500 nm with a spectral resolution of 0.5 nm Measures trace gases including: O 3, NO 2, HCHO, BrO, OClO, and SO 2Measures trace gases including: O 3, NO 2, HCHO, BrO, OClO, and SO 2 Also measures aerosol characteristics, cloud top heights, cloud coverage, and surface UV irradiance.Also measures aerosol characteristics, cloud top heights, cloud coverage, and surface UV irradiance. Ahmad et al., 2003

8. COSPEC COSPEC – Correlation SpectrometerCOSPEC – Correlation Spectrometer Principal tool for remote measurements of SO 2 since 1970’sPrincipal tool for remote measurements of SO 2 since 1970’s Measures UV radiation from 300 – 315 nm, specifically 9 peaks and troughs of the SO 2 absorption curveMeasures UV radiation from 300 – 315 nm, specifically 9 peaks and troughs of the SO 2 absorption curve Spinning disk allows transmission of light only for those exact wavelengthsSpinning disk allows transmission of light only for those exact wavelengths Compares the measured absorption by SO 2 against known calibration cells to determine amount of SO 2 present in the plumeCompares the measured absorption by SO 2 against known calibration cells to determine amount of SO 2 present in the plume (units of ppmm) Elias et al., 2005

9. COSPEC at Mount St. Helens Photo by Lyn Topinka, USGS 1983

10. Methods

11. Methods Looked at 8 days throughout the eruption that corresponded with gas flights, only 4 days with OMI SO 2 at 5 km:Looked at 8 days throughout the eruption that corresponded with gas flights, only 4 days with OMI SO 2 at 5 km: 9/23/06; 9/24/06; 9/30/06; and 10/12/06 Dates after October 12 did not have OMI SO 2 products for 5 km– low UV?Dates after October 12 did not have OMI SO 2 products for 5 km– low UV?

12. Gas Flight Traverses 9/23/06 Data provided by Mike Doukas USGS-VEP

13. Converting OMI Data Granules into Images Free OMI data from: http://disc.sci.gsfc.nasa.gov/data/datapool/OMI/Level2/O MSO2/Free OMI data from: http://disc.sci.gsfc.nasa.gov/data/datapool/OMI/Level2/O MSO2/ http://disc.sci.gsfc.nasa.gov/data/datapool/OMI/Level2/O MSO2/ http://disc.sci.gsfc.nasa.gov/data/datapool/OMI/Level2/O MSO2/ –Select date and spatial subset –Download appropriate data granules (up to 14) OMI data files are in HE5 formatOMI data files are in HE5 format Open data files in HDF ExplorerOpen data files in HDF Explorer I was interested in 3 things: SO 2 Column Amount at 5 km, Latitude, and LongitudeI was interested in 3 things: SO 2 Column Amount at 5 km, Latitude, and Longitude In HDF Explorer I could view a map of the data and could export data as text filesIn HDF Explorer I could view a map of the data and could export data as text files Produce map in ArcMap and interpolate between the data valuesProduce map in ArcMap and interpolate between the data values

14. HDF Explorer Maps Left: SO 2 Column Amount (15 Km) Right: Terrain Height (data for 9/23/06)

15. Results

16. Results 9/23/06 Gas flight T1:Gas flight T1: –Max SO 2 = 665 ppmm (~66.5 DU) –Average SO 2 = 328 ppmm (32.8 DU) –Plume width ~2 Km –Plume Length estimated to be ~6 Km –Plume Area ~12 Km 2 OMI Pixel ~ 13 x 42 Km (546 Km 2 )OMI Pixel ~ 13 x 42 Km (546 Km 2 ) (not at nadir) SO 2 value for nearest OMI pixel = 0.24 DU

17. OMI Swath for 9/23/06 Overlain on Alaska Shapefile

18. Fourpeaked Measurements 9/23/06 (Kriging Interpolation)

19. Gas Flight Traverse 1 Overlain on OMI Interpolation (9/23/06)

20. Traverse 1: Assume Plume Area of 22.8 Km 2 For 32.8 DU = 747.84 DU*Km 2 Pixel Area (not at nadir) = 13 x 42 Km (546 Km 2 ) (assume 0 DU for remainder of Pixel) 747.84 DU*Km 2 + 0*534DU*Km 2 = 546X X = 1.37 DU = Average Pixel Value OMI Measured SO 2 = 0.24 DU 32.8 DU 0 DU 23.4 Km 4.77 Km

21. Gas Flight Traverses 1, 5 & 7 Overlain on OMI Interpolation

22. Traverse 7: Assume Plume Area of 60 Km 2 For 18.9 DU = 1134 DU*Km 2 Pixel Area (not at nadir) = 13 x 42 Km (546 Km 2 ) (assume 0 DU for remainder of Pixel) 1134 DU*Km 2 + 0*534DU*Km 2 = 546X X = 2.1 DU = Average Pixel Value OMI Measured SO 2 = 0.24 DU 32.8 DU 0 DU 23.4 Km 4.77 Km

23. Fourpeaked 9/23/06 Zoomed Out

24. Puff Model 9/23/06

27. Fourpeaked 9/24/06 Results (IDW Interpolation)

28. Puff Model 9/24/06

31. Fourpeaked Results 9/30/06 (IDW Interpolation)

32. Puff Model 9/30/06

35. Discussion & Conclusions

36. Discussion OMI does appear to have been able to detect SO 2 emitted from Fourpeaked volcanoOMI does appear to have been able to detect SO 2 emitted from Fourpeaked volcano –SO 2 values are not significantly above noise levels –Puff models in general support plume locations The values detected using OMI were lower than the airborne measurements (1.37 DU calculated for airborne vs. 0.24 for OMI)The values detected using OMI were lower than the airborne measurements (1.37 DU calculated for airborne vs. 0.24 for OMI) The spatial resolution (13 x 24 Km at nadir or larger for off nadir) is a limiting factor in detecting passive degassing from volcanoes by OMIThe spatial resolution (13 x 24 Km at nadir or larger for off nadir) is a limiting factor in detecting passive degassing from volcanoes by OMI

37. Conclusions OMI data compared fairly well to airborne measurements once a spatial correction was applied (many assumptions in this calculation)OMI data compared fairly well to airborne measurements once a spatial correction was applied (many assumptions in this calculation) While OMI is able to detect “passive” degassing emissions – these emissions must have very high SO 2 concentrations or have a large plume area to distinguish from noiseWhile OMI is able to detect “passive” degassing emissions – these emissions must have very high SO 2 concentrations or have a large plume area to distinguish from noise Because anomalies are not much higher than noise, false alarms could result if used for monitoring purposesBecause anomalies are not much higher than noise, false alarms could result if used for monitoring purposes

38. Conclusions Continued OMI may not be useful for monitoring high latitude volcanoes in winter (this requires further investigation)OMI may not be useful for monitoring high latitude volcanoes in winter (this requires further investigation) Automated processing routine and spatial zoom- in modes would greatly increase the usefulness of this techniqueAutomated processing routine and spatial zoom- in modes would greatly increase the usefulness of this technique More testing would need to be done to determine if OMI would be a useful monitoring tool (benefits outweigh costs)More testing would need to be done to determine if OMI would be a useful monitoring tool (benefits outweigh costs)

39. Acknowledgements Anupma Prakash (UAF)Anupma Prakash (UAF) Rudi Gens (UAF)Rudi Gens (UAF) Mike Doukas (USGS-VEP)Mike Doukas (USGS-VEP) Cindy Werner (USGS-VEP)Cindy Werner (USGS-VEP) Ken McGee (USGS-VEP)Ken McGee (USGS-VEP) Chris Nye (Alaska DGGS)Chris Nye (Alaska DGGS) Simon Carn (University of Maryland-NASA)Simon Carn (University of Maryland-NASA) Suraiya Ahmad (NASA)Suraiya Ahmad (NASA) Lovro Valcic (UAF)Lovro Valcic (UAF) Peter Webley (UAF)Peter Webley (UAF) Peter Rinkleff (UAF)Peter Rinkleff (UAF)

40. Thanks for Listening! Questions?

41. NASA Products 9/17/06

42. My Processing of “Same” File (9/17/06 Orbit 11573): Note Swath Edge