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COST 727 Action

COST 727 Action. COST: European Cooperation in Science and Technology. Measuring and forecasting atmospheric icing on structures. Alain Heimo Meteotest, Switzerland MC Chairman/COST727.

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COST 727 Action

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  1. COST 727 Action COST: European Cooperation in Science and Technology Measuring and forecasting atmospheric icing on structures Alain Heimo Meteotest, Switzerland MC Chairman/COST727 COST is one of the longest-running instruments supporting co-operation among scientists and researchers across Europe.

  2. Atmospheric icing: Why is it a problem? Atmospheric icing causes severe financial losses and reduces security and human safety : - Power line transmission …

  3. Spain 2002 Germany 2005 Norway 1961

  4. Atmospheric icing: Why is it a problem? • Atmospheric icing causes severe financial losses and reduces security and human safety : • Power transmission • Icing of structures (e.g.:TV- and telecommunication towers, ski-lifts) ...

  5. Design of loads, safety, operational stops.. On TV-towers the ice load may be several tens of tons.

  6. Atmospheric icing: Why is it a problem? • Atmospheric icing causes severe financial losses and reduces security and human safety : • Power transmission • Icing of structures (e.g.:TV- and telecommunication towers, ski-lifts) • Telephone lines, Forest economy...

  7. Ice load + high winds !

  8. Atmospheric icing: Why is it a problem? • Atmospheric icing causes severe financial losses and reduces security and human safety : • Power transmission • Icing of structures (e.g.:TV- and telecommunication towers, ski-lifts) • Power lines, Telephone lines, Forest economy • Wind turbines...

  9. Uncertainities in prediction of production • Additional loads /design • Safety: falling ice, operational safety • Reduction in power production due to: • reduced lift • shut-down • mechanical • failures • iced wind • sensors

  10. Atmospheric icing: Why is it a problem? • Atmospheric icing causes severe financial losses and reduces security and human safety : • Power transmission • Icing of structures (e.g.:TV- and telecommunication towers, ski-lifts) • Power lines, Telephone lines, Forest economy • Wind Power production • Aviation ...

  11. Icing at airports and in the air No icing Icing source: http://meted.ucar.edu

  12. Atmospheric icing: former activities WMO/CIMO Wind Instrument Intercomparison Mont Aigoual, France, 1992-1993 Organized by France, Switzerland & WMO Participating countries: 11 Instruments tested: 26 Jungfraujoch, Switzerland • Conclusions from the final report: • … The formation of ice makes almost all the calculated parameters incoherent. • … We have not been able to characterize the icing phenomena from ice detectors. • … It appears difficult to be both “accurate” and rugged for severe icing. Jungfraujoch, Switzerland

  13. Atmospheric icing: former activities EUMETNET SWS-II (2000-2003) Goal: Acquisition of meteorological data under icing conditions in Finland (Luosto), France (Mt. Aigoual) and Switzerland (Säntis) Measurement period: 1.10.2001 to 30.4.2002 Luosto, finland Conclusions and recommendations: - …. Already during the installation and test period proceeding the experiment, it was quickly recognized that the lack of adequate instruments for the characterization of ice accretion would represent a serious drawback for the whole experiment. - … it is important thatmore care is given within the meteorological community to produce accurate measurements under harsh conditions and to promote measurements of icing.

  14. COST 727 Main Objectives (MoU 2004): • to develop the understanding of icing • (especially in-cloud icing) and freezing rain • in the atmospheric boundary layer (ABL) • to produce information on distribution of • icing over Europe • to improve the potential to • observe icing • monitor icing • forecast icing

  15. Participating countries Non-COST Participant: Japan (Kanagawa Institute of Technology)

  16. Objectives: • To develop scientific understanding of icing processes together with modeling and forecasting of icing. • Measurements: • To compile existing sources of icing data in Europe • To harmonize ongoing measurement programs in Europe • To fulfill the WMO/CIMO request to provide guidance for performing measurements under harsh icing conditions. • To promote the development of robust, rugged icing detectors to be deployed at automatic meteorological stations as well as at other sites where icing effects may be critical. Simple sensors delivering a yes/no information are needed as well as more sophisticated instruments yielding values of ice thickness/weight, types of ice. • Modelling: • To develop numerical meteorological models for icing studies with improved icing parameterizations and verification of icing models with ground-truth data. • To perform climatological icing studies and mapping of icing severity

  17. Measurements of icing • Achieved during the last 2 years: • Based on preliminary measurements, selection of 2 «  reference » sensors for the detection of ice accretion (Goodrich 0847LH1) and for the measurement of ice loads (Combitech Mk I) • Principle: ultrasonic resonance • promising results from earlier studies • difficult to get it from manufacturer (military regulations) • only little measurement data available • Principle: weighting of ice • designed according to ISO 12494 definition • operational from the beginning • promising results • design improvements needed (e.g. oscillations)

  18. Measurements of icing • Achieved during the last 2 years: • Based on preliminary measurements, selection of 2 «  reference » sensors for the detection of ice accretion (Goodrich 0847LH1) and for the measurement of ice loads (Combitech Mk I) • Calibration of the « reference » instruments in a dedicated icing wind tunnel facility (Kanagawa Institute, Tokyo, Japan)

  19. Icing wind tunnel test in Cryospheric Environment Simulator at Shinjo Branch of National Research Institute for Earth Science and Disaster Prevention in Kanagawa Institute of Technology < 20m/s (with a larger test section) < 100m/s (in a smaller test section) > -25 deg. Cel. < 20m/s (1m by 1m test section) > -25 deg. Cel. Sprayers not installed all the time

  20. Measurements of icing • Achieved during the last 2 years: • Based on preliminary measurements, selection of 2 «  reference » sensors for the detection of ice accretion (Goodrich0847LH1) and for the measurement of ice loads (Combitech Mk I) • Calibration of the « reference » instruments in a dedicated icing wind tunnel facility (Kanagawa Institute, Tokyo, Japan) • Installation and operation of 6 test stations in Europe equipped with the Combitech Mk I (2007:2008) and the Goodrich 0847LH1 (2008): Luosto (Finland), Sveg (Sweden), Zinnwald (Germany), Deadwater Fell (United Kingdom), Studnice (Czech Republic) and Guetsch (Switzerland)

  21. European test stations

  22. Switzerland (Guetsch test station) Czech Republic (Studnice) Germany (Zinnwald)

  23. Luosto fell, Finland Åre, Sweden Deadwater Fell, UK

  24. Measurements of icing • Achieved during the last 2 years: • Based on preliminary measurements, selection of 2 «  reference » sensors for the detection of ice accretion (Goodrich 0847LH1) and for the measurement of ice loads (Combitech Mk I) • Calibration of the « reference » instruments in a dedicated icing wind tunnel facility (Kanagawa Institute, Tokyo, Japan) • Installation and operation of 6 test stations in Europe equipped with the Combitech Mk I (2007:2008) and the Goodrich 0847LH1 (2008): Luosto (Finland), Sveg (Sweden), Zinnwald (Germany), Deadwater Fell (United Kingdom), Studnice (Czech Republic) and Guetsch (Switzerland) • Setup of the first European Icing Dataset containing all meteorological parameters necessary for icing modeling and simulation -> winter 2007-2008: selection of 3 major icing events for each station

  25. Modelling icing of structures • The theoretical basic knowledge is presently available, based on the ISO 12494 standards (Makkonen formula) and new cloud microphysics schemes built in the WRF model code • Verification data are now available and standardized for sites located all around Europe. Unfortunately more data (winters) are needed. • Preliminary results show that the current version of the WRF model is able to perform very accurate simulations of icing events at all test stations in Europe (especially for the collapse of a measurement tower in Switzerland) • Measured site information about the Liquid Water content and Droplet Size Distribution are still missing • Tentative simulation runs of wet snow accretion and freezing rain events have been started

  26. Numerical modeling of ice accretion • WRF is a modern mesoscale, non-hydrostatic numerical weather prediction model developed mainly by NCAR, NOAA and NCEP (USA) designed for mesoscale and high resolution forecasts. • WRF has the advantage of a very sophisticated calculation of clouds and precipitation. • Applications from Large Eddy Simulations: Δx = 100m • to regional climate simulations: Δx = 100km. • WRF is meant to gradually replace its predecessor, MM5.

  27. Numerical modeling of ice accretion Following the ISO12494 standard (Atmospheric icing of structures), the in-cloud ice accretion on a cylinder can be expressed by the formula: where a1 = Collision efficiency a2 = Sticking efficiency a3 = Accretion efficiency w = Mass concentration of cloud water (LWC) A = Cross sectional area V = Wind speed • Specific input data from measurements or from 3D weather models • are needed to compute α1 and α 3: • Temperature, Wind speed, humidity <- standard measurements • LWC <- Simulated by WRF • Median Volume Droplet size <- unknown at present (fixed value assumed). Test simulations have been carried out with the weather model WRF extended with the above algorithm.

  28. Case #1: Luosto (Finland) December 2007 WRF simulation

  29. 96h WRF simulation 800m grid size

  30. 120h WRF simulation 800 m grid size

  31. Case #2: Schwyberg (Switzerland) November 2007 WRF simulation

  32. Tower collapse at Schwyberg, Switzerland Data acquisition failure Ice load and strong winds -> tower collapse

  33. Case #3: Mapping (tentative)28.12.2007 – 7.01.2008 WRF simulation

  34. Activitiesuntil end of Action • Measurements • Continuous operation of the 6 test stations equipped with the 2 “reference” instruments • Upgrade of the present instruments together with the manufacturer • Extend dataset with the winter 2008-2009 measurements • Modeling • Upgrade WRF model with updated microphysics (PhD) • Perform simulations based on the EID • Perform sensitivity studies with LWC and MVD

  35. For further details, please visit poster P2(40) Announcement: The Final Workshop of COST-727 Action 13th International Workshop on Atmospheric Icing on Structures IWAIS will be held jointly in Andermatt (Switzerland) , 8-11.9.2009 Please register at: www.IWAIS2009.ch Thank you for your attention !

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