1. Page 1© Crown copyright 2006 Overview of VAAC Activities Claire Witham SACS Workshop 3 October 2006

2. Page 2© Crown copyright 2006 Outline  Introduction  VAAC Role  Current tools  London VAAC  Case study Acknowledgements: Raul Romero (ICAO Secretariat), Nigel Gait (London VAAC) and Helen Champion (Met Office)

3. Page 3© Crown copyright 2006 Introduction

4. Page 4© Crown copyright 2006 Volcanic Hazards to Aircraft  Volcanic clouds can contain:  Rock fragments, fine particles (ash), corrosive gases (incl. SO 2 ), water vapour  Ash is a major hazard to aviation:  Abrasive; clogs sensors  Melts in engines (melting point ~1100C)  SO 2 is also a hazard:  Corrosive

5. Page 5© Crown copyright 2006 Encounters  90+ aircraft damaged by ash clouds  7+ cases of in-flight loss of power  Three 747’s have lost all engines (Indonesia 1982, Alaska 1989)  Pinatubo - aircraft damaged >1000km from eruption  Average 10 eruptions per year reach flight levels  Economic cost estimation of US$ 250 Million between 1982-2000  Avoidance of ash clouds only safe procedure for aircraft, but:  in cloud or at night cannot be seen  not visible on radar

6. Page 6© Crown copyright 2006 Response to Hazard  To face the threat, ICAO established:  Guidelines for dissemination of information on volcanic ash to pilots  Contingency arrangements for diversion of aircraft  Formal amendments to ICAO Annexes and PANS  The ICAO Volcanic Ash Warning Study Group (VAWSG) in 1982  The International Airways Volcano Watch (IAVW) to enable:  International arrangements for monitoring and providing warnings to aircraft of volcanic ash in the atmosphere

7. Page 7© Crown copyright 2006 History  Difficulty in providing accurate info out to 12 hrs led to:  Designation of VAACs, on advice from WMO  SIGMET and outlook  Operational procedures developed  Involvement of other international organisations  Establishment of IAVWOPSG (2003)  Recent developments of graphical output  Responsibilities outlined in Annex 3 (November 1998)  Operational procedures included in the Handbook of the IAVW (Doc 9766)

8. Page 8© Crown copyright 2006 Structure of the IAVW Two areas of responsibility:  Observing  Detection of eruptions and volcanic ash by a range of sources  Notification to MWOs, ACCs & VAACs  Warning  Volcanic ash advisories (by VAACs)  Alphanumeric and graphical format  SIGMETs (by MWOs)  NOTAMs/ASHTAMs (by ACCs)

9. Page 9© Crown copyright 2006 Operational Observations Three components of observing network:  Ground-based component  Difficulties in receiving initial notification  Air-reporting component  Operating well in general  Further work is necessary  Space-based component  Satellite data critical  Scope for improvement Role for SACS

10. Page 10© Crown copyright 2006 VAAC Role

11. Page 11© Crown copyright 2006 VAAC Designation  To ensure rapid warnings to aviation the IAVW set-up 9 Volcanic Ash Advisory Centres (VAACs), including London and Toulouse  VAAC responsibilities to aviation users:  Utilise satellite data, Pilot reports (PIREPS) etc to detect and track ash clouds  Use trajectory/dispersion models to forecast ash plumes

12. Page 12© Crown copyright 2006 Warning component  VAAC Provider States  Areas of responsibility determined by the coverage of satellite information  Main international airways covered first  Organised tracks with adequate coverage  Future coverage to protect dynamic and flexible operations.  Adequate coverage with the extension of areas of responsibility of VAACs Toulouse and Washington

13. Page 13© Crown copyright 2006 Areas of Responsibility

14. Page 14© Crown copyright 2006 VAAC Role  Aim is to forecast location of ‘ash cloud mass’ and issue warnings to aviation  SO 2 and sulphuric acid also pose a hazard and may indicate position of dilute ash  Hazard depends on  Eruption rate  Concentration of ash/SO 2  Particle size  Moisture

15. Page 15© Crown copyright 2006 Advisories  Information made available as text messages - Volcanic Ash Advisory Statements (VAAS)  VAAS used to issue SIGMETS, NOTAMS/ASHTAMS to aviation users  Contain:  General info - volcano involved, summit height etc  Source of information used (e.g. satellite, webcams)  Description of ash cloud - density, area & height  Current cloud movements and forecast  Updated 6 hourly

16. Page 16© Crown copyright 2006 Advisories  Example of Volcanic Ash Advisory  Effectiveness:  In general satisfactory  Difficulties in some areas with absence of SIGMETs Subject: FVUK01 EGRR 020615 FVUK01 EGRR 020615 VOLCANIC ASH ADVISORY ISSUED: 20041102/0600Z VAAC: LONDON VOLCANO: GRIMSVOTN 1703-01 LOCATION: N6416W01716 AREA: ICELAND SUMMIT ELEVATION: 1725M ADVISORY NUMBER: 2004/03 INFORMATION SOURCE: ICELANDIC MET SERVICE AVIATION COLOUR CODE: UNKNOWN ERUPTION DETAILS: VAAC LONDON HAS RECEIVED CONFIRMED REPORTS THAT THE GRIMSVOTN VOLCANO HAS ERUPTED, ESTIMATED START 20041101/2200Z. THE ICELANDIC MET OFFICE CONFIRM THAT THE ASH CLOUD HAS REACHED FL400. OBS ASH DATE/TIME: 02/0600Z. OBS ASH CLOUD: ASH JUST SHOWING ON LATEST SATELLITE IMAGERY, APPROX 25KM WIDE FROM N6416W01716 TO N6630W01400, MOV NE AROUND 50KT. FCST ASH CLOUD + 6HR: 02/1200Z SFC/FL200 N6416W01716-N6900W01400-N7200W00500-N7200E00200-N6600W01100- N6424W01719. FL200/350 N6416W01716-N6930W00900-N7200E00400-N6800E01400-N6400E01300- N6700W00300-N6416W01716. FL350/550 N6416W01716-N7100E00100-N6800E01200-N6500E01200-N6700W00200- N6416W01716. FCST ASH CLOUD + 12HR: 02/1800Z

17. Page 17© Crown copyright 2006 Current Tools

18. Page 18© Crown copyright 2006 Resources Used by VAAC Forecasters  Reports from Meteorological Offices and Geological Surveys  Satellite imagery:  visible and infrared  polar & geostationary  processed satellite imagery to detect ash  TOMS/OMI aerosol and SO 2  Standard forecasting tools (including detailed met forecasts)  PIREPS (pilot reports)  Ground observations, webcams  Weather radar  Seismic activity  Atmospheric dispersion modelling (requires input data)  Forecaster experience from training, rehearsals and prior eruptions

19. Page 19© Crown copyright 2006 Satellite Ash Detection Products  Routinely received AVHRR data are used to generate a volcanic ash product  ch4 (10.8  m) - ch5 (12.0  m)  available within 30 mins  MSG images every 15 minutes  Data covering four areas automatically generated and displayed on London VAAC internal web :  Iceland and London VAAC area of responsibility (updated ~ every 3 hours)  Mediterranean area (Mt. Etna) (~ every 6 hours)  Central Africa  Caribbean AVHRR ch4-ch5 (BT 10.8 - BT 12.0 ) < 0 volcanic ash AVHRR ch4-ch5 (BT 10.8 - BT 12.0 ) > 0 water & ice

20. Page 20© Crown copyright 2006 Other Products Radar data (courtesy of the Icelandic Meteorological Office) Seismic data Local observations

21. Page 21© Crown copyright 2006 Data Available During Eruptions  All data sources have limitations…  Ground/aircraft observations generally only available in daytime  Data scarce for remote eruption locations  Satellite ash detection hindered by cloud  Weather radar data has limited range and detection capabilities  Reliance on modelling when other data limited

22. Page 22© Crown copyright 2006 Modelling Volcanic Ash Clouds  Aim is to predict location and movement of ‘visual ash cloud’  Lagrangian and Eulerian dispersion models  Run on 3-D meteorology from NWP models  Rapid run times  Only data source that provides a forecast

23. Page 23© Crown copyright 2006 Prescribed Parameters  The minimum parameters required to initialise VAAC models are:  Eruption latitude  Eruption longitude  Crater height  Eruption height  Start-time of eruption  Output is required every 6-hours for ‘visual’ volcanic ash for flight level slices: surface-FL200, FL200-FL350, FL350-FL550 and surface-FL550

24. Page 24© Crown copyright 2006 Model Uncertainties  Unfortunately ‘visual ash’ is not defined and depends on  Concentration and type of particles  particle size  humidity ?  Even if ‘visual’ was defined in terms of a concentration, we rarely know the source term so defaults required.  Validation of model output is difficult

25. Page 25© Crown copyright 2006 London VAAC

26. Page 26© Crown copyright 2006 London VAAC  Operated 24-7 by forecasters at the UK Met Office (based in Exeter)  Tools developed by R&D scientists at the Met Office  Regular consultation between forecasters and R&D  Area covered is the North Atlantic, including Iceland  Busiest oceanic air traffic corridor in the world

27. Page 27© Crown copyright 2006 Volcanoes in London VAAC  Area of strong volcanic activity - 19 volcanoes active in the last 10,000 years  Approx. one eruption every 2-3 years in the area  Recent major eruptions in 1996,1998, 2000, 2004  NASA aircraft damaged in 2000

28. Page 28© Crown copyright 2006 The NAME dispersion model  Atmospheric Lagrangian particle dispersion model  3D met data from global NWP model  Range:  1-10000km  hours-days  Predicts:  3D air concentrations  Extent of visual ash cloud  Deposition  Output:  T+6,12,18, 24  Four levels

29. Page 29© Crown copyright 2006 Daily runs  Daily simulations using NAME  Improve response times and preparedness  Releases from Katla and Grimsvotn  6 hour release  At 0, 6, 12 & 18Z  surface to FL400  Output on six levels

30. Page 30© Crown copyright 2006 Case Study

31. Page 31© Crown copyright 2006 Grimsvötn Eruption  Grimsvötn, Iceland erupted on the evening of 1 Nov 2004  Broke through Vatnajokull ice cap at 22:50  <1 km long fissure  Eruption column to 12-14 km  Ash deposited over Iceland and Scandinavia  Second, low intensity, phase of eruption 3-4 Nov.  Little observation data available at the time Plume on the afternoon of 2/11/04. (Image from www.norvol.hi.is.)

32. Page 32© Crown copyright 2006 Infrared AVHRR image from 03:45 UTC on 2/11/2004 showing the plume in the early stages of the eruption. Iceland Meteosat-8 (MSG) cloud top height image showing the large amount of cloud overlying the area on 2/11/04.

33. Page 33© Crown copyright 2006 Comparison of NAME to SO 2 Data Several hours after the start of the eruption SO 2 slant column data from SCIAMACHY NAME volcanic ash Surface – FL550 composite

34. Page 34© Crown copyright 2006 Comparison cont’d Two and a half days after the start of the eruption SO 2 slant column data from SCIAMACHY NAME volcanic ash Surface – FL550 composite

35. Page 35© Crown copyright 2006 Summary

36. Page 36© Crown copyright 2006 Summary  VAACs set-up to detect, track and forecast volcanic ash clouds  Satellite data is a primary source of information on plume location  Previous focus has been on detecting ash  Increased awareness of potential hazard from SO 2 and sulphuric acid  Satellite SO 2 data for Grimsvotn and other eruptions crucial in verifying modelled long- range plume transport