EUMETSAT Volcanic Ash Products Marianne Knig EUMETSAT EumetsatAllee

EUMETSAT Volcanic Ash Products Marianne König EUMETSAT Eumetsat-Allee 1 D-64295 Darmstadt, Germany www. eumetsat. int marianne. koenig@eumetsat. int 19 April 2013

Summary Slide • Following the 2010 Eyjafjalla eruption, EUMETSAT was tasked to make a volcanic ash product operationally available, using the MSG-SEVIRI satellite information • A volcanic ash retrieval algorithm was developed through a scientific collaboration with Dr. Fred Prata (NILU); the product is operationally available since May 2012 • Several areas of improvement are identified and will be worked on in the future (initial ash detection, algorithm change to a full optimal estimation type of approach) • Future plans concerning Metop and MTG 19 April 2013

MSG-SEVIRI Instrument Characteristics SEVIRI 15 min repeat cycle for full disk 5 min repeat cycle for RSS 3 km (1 km) spatial resolution Slide 19 April 2013 12=HRV 1=VIS 0. 6 2=VIS 0. 8 3=NIR 1. 6 4=IR 3. 8 5=WV 6. 2 6=WV 7. 3 7=IR 8. 7 8=IR 9. 7 9=IR 10. 8 10=IR 12. 0 11=IR 13. 4

SEVIRI Ash Detection: Why does it work? Slide 19 April 2013

SEVIRI Ash Detection – Example for 15 April 2010, 14 UTC Slide 19 April 2013

SEVIRI Ash Detection: Simple BTD Test Slide 19 April 2013 IR 10. 8 -IR 12. 0 Ash detection Prata v 1 Meteosat-9, 201004015, 14: 00 UTC

Refinements Use of other channels in this thresholding technique: e. g. Slide Combination of IR 3. 9 and VIS 0. 6 (daytime) … (TBC!) Combination of IR 3. 9, IR 8. 7, IR 10. 8 and IR 12. 0 at all times, together with predicted clear-sky brightness temperatures in these channels (from forecast fields) together with a spatial consistency check 19 April 2013

SEVIRI Ash Detection: Less False Alarms Slide 19 April 2013 IR 10. 8 -IR 12. 0 Ash detection v 2010 Meteosat-9, 201004015, 14: 00 UTC

For Detected Ash: Retrieval of Quantitative Information (following scientific collaboration with Dr. Fred Prata, NILU) Background: Retrieval of effective particle size and optical depth as a function of the BTD difference IR 10. 8 – IR 12. 0 (and some other parameters) , from pre-defined lookup-tables (computed using a given spectroscopic dataset). Combining the size and optical depth gives the total mass loading as the final product. Note: “Thick” ash clouds cannot be discriminated from opaque water/ice clouds! Slide 19 April 2013

Application Example Theoretical behaviour of spherical water droplets with radii >50 µm Theoretical behaviour of spherical silicate particles with 1 µm radius Slide Eumetsat, Darmstadt 19 April 2013 11

SEVIRI Ash Retrieval - Example Slide 19 April 2013

SEVIRI Ash Retrieval - Validation Corresponds to mass loading of ~ 0. 4 g/m 2 Slide 19 April 2013

SEVIRI Ash Retrieval - Validation Corresponds to mass loading of ~ 0. 2 g/m 2 Slide 19 April 2013

SEVIRI Ash Retrieval - Validation Additional information on ash cloud thickness was used to turn MSG total mass loadings into concentrations: Very good agreement found in this case (assumption is that concentration is vertically homogeneous) Slide 19 April 2013

SEVIRI Ash Retrieval - Validation Less good agreement found in this case – but note: These are very low concentrations! Slide 19 April 2013

SEVIRI Ash Retrieval - Validation SEVIRI can derive total mass loading, and with additional information on ash cloud thickness (models, other measurements), this can be turned into mass concentrations. SEVIRI can thus derive ash concentrations over the entire range of interest Very thick ash is not detected Ash below thick clouds is not detected Reliable detection remains a problem Slide 19 April 2013

SEVIRI Volcanic Ash Product The ash product is available in the following formats: • net. CDF format (with ash effective radius, mass loading, height (incl. quality) per pixel) – 96 times per day and in case of an event (upon request from the London VAAC): • CAP (Common Alert Protocol) format • Text files • Image (PNG format) Slide 19 April 2013

Word of Caution No full validation of the operational product done yet – satellite product should always be used in combination with other information! Example: Combination with “visual” impression from the RGB composites, e. g. the RGB colour composites IR 12. 0 – IR 10. 8 - IR 8. 7 IR 10. 8 April 2010 May 2010 Slide 19 April 2013

SEVIRI Ash Detection Future Plans • Reliable ash detection still a problem • Improvements and tests are ongoing • Collaboration with UK Met Office (Peter Francis) and Fred Prata • Plans to investigate all volcanic eruptions in the Meteosat FOV • Use of two Meteosats for stereo height assignment • Plans for including the detection of SO 2 • Explore potential of an optimal estimation approach (promising especially in case of ash above lower clouds) – Science Study with RAL in 2013 ; OE approach: fitting radiances of all channels to find best solution for ash properties, notably also height Slide 19 April 2013

Volcanic Ash: OE Approach One layer Two layers 19 April 2013

International Collaboration CGMS resolution at its 40 th meeting (2012): ”EUMETSAT, JMA and NOAA are invited to report on their development toward common and consistent volcanic ash products from Meteosat and MTSAT-2 and GOES, respectively. “ JMA and KMA have received a copy of our prototype code (following the Prata algorithm) and will make the product operationally available for MTSAT and COMS, in order to have a globally consistent product Slide 19 April 2013

EUMETSAT Polar System NOAA / NPP (NOAA) Metop (EUMETSAT) Suite of Instruments: Imager (AVHRR) Infrared Sounding (HIRS and IASI) UV-VIS (GOME-2) … Microwave sounding Scatterometer Radio-occultation 19 April 2013

Future Plans – Metop Development ongoing towards a “multi-mission” aerosol product (mainly aerosol optical depth) “Multi-mission”: GOME & AVHRR & IASI onboard Metop First version available in ~mid 2013 Extension to include a volcanic ash flag – in 2014 Slide 19 April 2013

Metop Aerosol Product Example Global: Aerosol optical depth (GOME) Volcanic ash event around Iceland: preliminary 23 May 2011 Orange: Strong ash test positive, cloud tests ignored Blue: cloud fraction < 0. 3, AOD retrieved Slide White: • no retrieval or • cloud fraction > 0. 3 and negative ash test 19 April 2013 Aerosol optical depth (GOME)

Future Missions: Meteosat Third Generation MTG The MTG satellite system will include a sounding satellite, carrying an Infrared Sounder. Volcanic ash products from the sounder will be similar to what is currently available for e. g. IASI MTG time schedule: Imager satellite to be launched in Dec 2018 (similar to MSG, improved spatial/temporal resolution, more shortwave channels) Sounding satellite: To be launched 2 years later Slide 19 April 2013

MTG IRS 1740 spectral samples at 4 km resolution, full disk coverage every 60 minutes, European area covered every 30 minutes H 2 O(p) CO 1600 – 2175 cm-1 T(p) Sfc O 3 Sfc 700 – 1210 cm-1 Surface, Clouds Temp (CO 2) Surface, Clouds CO O 3 N 2 O, Temp (CO 2) Slide 19 April 2013 H 2 O, CH 4, N 2 O Temp (CO 2)

MTG IRS Volcanic Ash Product Similar to current work using IASI (absorbing aerosol index): Université libre de Bruxelles, Belgium Cathy Clerbaux, Lieven Clarisse, P. Coheur, D. Hurtmans Slide 19 April 2013 Laboratoire Atmosphères, Milieux, Observations Spatiales, France