Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 Image: MODIS Land Group, NASA GSFC March 2000 A Cloud Object Based Volcanic Ash Detection Technique Presented by Michael Pavolonis Presented by Michael Pavolonis

Center for Satellite Applications and Research (STAR) Review 09 – 11 March Requirement, Science, and Benefit Requirement/Objective Mission Goal: Commerce and Transportation –Research Area: Provide accurate, timely, and integrated weather information to meet air and surface transportation needs. Science How can satellite data be used to quantitatively track dangerous volcanic ash clouds? How can satellite data products be used to validate and improve forecasts of ash cloud dispersion? Benefit These products will allow forecasters to issue more timely and accurate ash cloud warnings and forecasts to the aviation community, helping to reduce the risk of ash/aircraft encounters and limit the economic impact associated with rerouting aircraft around suspected ash clouds. The ash cloud property retrievals can be used to improve ash fall predictions. Ash fall poses a major hazard to life, property, and natural resources.

Center for Satellite Applications and Research (STAR) Review 09 – 11 March Challenges and Path Forward Science challenges –Product validation is difficult given the lack of in-situ observations of ash clouds. Next steps –Similar products are being developed for other sensors such as: GOES, MTSAT, MODIS, SEVIRI, VIIRS, GOES-R, AIRS, IASI, and CrIS. –Our goal is an automated combined LEO/GEO global volcanic ash monitoring system that will be a reliable tool for volcanic ash forecasters and modelers. Transition Path –The AVHRR component of this system is scheduled to be fully transitioned into NESDIS operations by May/June 2010 (a PSDI funded effort). –We have developed the algorithm which will be used to generate the operational GOES-R ash products. –Our goal is to transition the GOES products to NESDIS operations within the next few years. –End users: Volcanic Ash Advisory Centers (VAACs), Air Force, NRL, Modeling Community, Research Community

Center for Satellite Applications and Research (STAR) Review 09 – 11 March Ash Detection Method Volcanic Ash Meteorological Clouds In lieu of traditional brightness temperature differences, the ash detection algorithm utilizes effective absorption optical depth ratios ( -ratios) (Pavolonis, 2010a and Pavolonis 2010b), which isolate the desired microphysical signatures. Spatially connected candidate volcanic ash pixels are grouped into cloud objects. Spectral and spatial object statistics are used to determine which objects are ash clouds. Candidate ash objects Algorithm Innovation #1: Spectral Algorithm Innovation #2: Spatial

Center for Satellite Applications and Research (STAR) Review 09 – 11 March Ash Detection Method Volcanic Ash Meteorological Clouds In lieu of traditional brightness temperature differences, the ash detection algorithm utilizes effective absorption optical depth ratios ( -ratios) (Pavolonis, 2010a and Pavolonis 2010b), which isolate the desired microphysical signatures. Spatially connected candidate volcanic ash pixels are grouped into cloud objects. Spectral and spatial object statistics are used to determine which objects are ash clouds. Algorithm Innovation #1: Spectral Algorithm Innovation #2: Spatial Filtered ash objects

Center for Satellite Applications and Research (STAR) Review 09 – 11 March Retrieval Method An optimal estimation technique (Heidinger and Pavolonis, 2009) is applied to ash pixels to retrieve cloud temperature, emissivity, and a micro-physical parameter. The retrieved parameters are used to estimate cloud height, effective particle radius, and ash mass loading. An error estimate for each of the retrieved parameters is a by- product of the optimal estimation approach. These products can be used to improve ash dispersion and fallout forecasts. Ash Loading Ash Height Effective Radius Quantitative Ash Products

Center for Satellite Applications and Research (STAR) Review 09 – 11 March WarningProduct Quick-look Automated Ash Warning System The warning criteria is fully user configurable. In addition to the text message, an automatically generated, pre-analyzed false color image along with product images are supplied to the user. Quantitative description of ash cloud needed to issue accurate advisory

Center for Satellite Applications and Research (STAR) Review 09 – 11 March False alarm March eruptions April 1 and 4 eruptions During this 20 day period leading up to and including the 2009 eruptions of Redoubt, AK, only 2 false warnings occurred out of 474 full AVHRR scenes received directly at Gilmore Creek (GC), AK (0.5% of scenes received at GC). In other words, a forecaster can expect a false warning once every 7 to 10 days. Every eruptive event captured by the AVHRR was detected. Automated Warning Performance

Center for Satellite Applications and Research (STAR) Review 09 – 11 March Unique Early Warning Capability This is the first automated technique capable of identifying volcanic ash that is sequestered in ice, which is common in the early stages of the ash cloud lifecycle. Early detection of new eruption (ash is largely sequestered in ice) Remnant ash from previous eruption

Center for Satellite Applications and Research (STAR) Review 09 – 11 March Challenges and Path Forward Science challenges –Product validation is difficult given the lack of in-situ observations of ash clouds. Next steps –Similar products are being developed for other sensors such as: GOES, MTSAT, MODIS, SEVIRI, VIIRS, GOES-R, AIRS, IASI, and CrIS. –Our goal is an automated combined LEO/GEO global volcanic ash monitoring system that will be a reliable tool for volcanic ash forecasters and modelers. Transition Path –The AVHRR component of this system is scheduled to be fully transitioned into NESDIS operations by May/June 2010 (a PSDI funded effort). –We have developed the algorithm which will be used to generate the operational GOES-R ash products. –Our goal is to transition the GOES products to NESDIS operations within the next few years. –End users: Volcanic Ash Advisory Centers (VAACs), Air Force, NRL, Modeling Community, Research Community