1. Global Satellite Observations of Volcanic Plumes for Aviation Hazard Mitigation Kai Yang (GSFC/NASA and GEST/UMBC) Nick Krotkov (GSFC/NASA) Simon Carn (MTU), Arlin Krueger (UMBC), Gilberto Vicente (NOAA), Eric Hughes (NOAA)

2. Motivations For aviation decision support, timely information about volcanic plumes is needed, especially their spatial locations, mass loadings, and vertical extents. These measurements provide critical inputs to numerical models for forecasting volcanic cloud hazards.

3. Detection of Volcanic Ash IR ash detection: –Absorption of warm underlying IR emission by ash using spectral features to distinguish them from normal water clouds –Plume must be thin to allow sufficient IR transmission –Plume must be colder than underlying surface Fresh ash clouds are: –Dense, must wait until sheared to thin layer –Full of water/ice UV ash (AI) detection: –Absorption and scattering of UV radiation by ash provide spectral contrast that differs from normal clouds and Rayleigh scattering –Sunlight necessary Fresh ash clouds are: –Detected upon eruption –Independent of water/ice content or surface conditions –Detectable down to the lower troposphere –Not detectable at night

4. Kasatochi Ash, August 9th 2008 Volcanic Ash Detections: UV and IR AIRS Δ BT (°K) OMI Aerosol Index

5. SO 2 as proxy for more reliable volcanic plume detection and tracking Volcanic plume behavior –Explosive magmatic eruptions contain both ash and SO 2 –SO 2 is usually easier to detect than ash (proxy) –Dense ash falls out in 2 - 4 days –SO 2 lasts for weeks Value of UV data –Potential for early detection of ash (AI) and SO 2 –Provide direct (SO 2 ) plume height –Measure degassing to monitor volcanic unrest Many eruptions observed by Aura/OMI since 2005 for evaluating this approach

6. SO 2 and Ash detection in very fresh (< 2 hrs) eruption clouds from OMI Montserrat; 2/11/2010Okmok; 7/12/2008Kasatochi; 8/8/2008 SO 2 Ash

7. Global Span of Volcanic SO 2 Plumes: Kasatochi August 7, 2008

8. Direct SO 2 Plume Height Estimation GOME-2 OMI GOME-2 SO 2 : Total Mass:1.5 Mt OMI SO 2 : Total Mass:1.6 Mt SO 2 Height SO 2 Height Histogram

9. Comparison with CALIPSO Plume Height

10. Eyjafjallajökull Ash: Aerosol Index GOME-2 OMI

11. Eyjafjallajökull SO 2 Plume SO 2 column SO 2 height Height Histogram

12. NRT Volcano Monitoring The NOAA/NESDIS OMI SO2 product delivery and visualization user interface http://satepsanone.nesdis.noaa.gov/pub/OMI/OMISO2/ Global composites Volcano sectors Satellite orbit Digital images

13. NOAA OMI SO 2 experimental automated alarm system: Anomalous SO 2 concentrations automatically detected in the most recent OMI data: Merapi eruption November 5-6 Merapi (Java) eruption November 5-6 OMI SO 2 is used as proxy for volcanic clouds, can be seen longer than ash OMI UV Aerosol Index (AI) shows directly sunlight reflection by ash

14. Planned Research: Synergy of Joint UV and IR Retrievals Both UV and IR measurements are sensitive to ash particle size and composition, and its vertical location. Combining hyper-spectral UV (OMI, GOME2) and IR (AIRS, IASI) measurements provides greater constraints to a retrieval algorithm, and likely leads to more accurate estimates of volcanic ash height and loading.

15. Near-Real-Time data service (Aerosol Index/SO 2 amount and height) from UV sensors: NPP/OMPS and ESA/TROPOMI Improvement in quantification of volcanic ash loading and height, likely achieved by combining retrievals of hyper-spectral UV and IR measurements Improvement in volcanic ash monitoring and forecasting by merging satellite measurements and numerical models Future Efforts