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Wind Doppler Lidars for Monitoring Dynamics in the PBLL

This paper discusses the basics of Doppler lidar technology, its accuracy and availability of measurements, and its operational applications in meteorology, climate, wind energy, and airport weather. It also explores the interaction between light and particles in the atmosphere and the use of lidars for weather aviation. The paper concludes by highlighting the development of a Wake Vortex Advisory System and the tracking of wake vortices at airports.

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Wind Doppler Lidars for Monitoring Dynamics in the PBLL

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  1. Wind Doppler Lidars to monitor the dynamics in the PBLL. Thobois, L. Sauvage, J. P. Cariou, S. Loaec, M. Mehdi, G. Gorju WMO TECHNICAL CONFERENCE ON METEOROLOGICAL AND ENVIRONMENTAL INSTRUMENTS AND METHODS OF OBSERVATION, Brussels, 2012

  2. Agenda • Bac to basics: the Doppler lidar principle • Availability and accuracy of measurements • Operational applications • Conclusion

  3. Bac to basics: Is Doppler lidar a new technology? • First Doppler lidars in 90’s • Different technologies available • Very few are really industrialized • ~500 Doppler lidars (estimated) installed in the world • Wind energy • Airport Weather • Meteorology,climate  Increasing demands for operational uses • What is a Doppler lidar?

  4. Bac to basics: Doppler Lidar post-processing wind velocity reconstruction Time gating Spectral analysis Averaging Frequency estimation V t • For each pulse, signal divided into slices (range gates) • Spectral analysis is computed on each range gate • Measurement at each range gate are an average over the sounded volume • Spatial resolution varies from 20m to 200m tm FFT FFT FFT

  5. Bac to basics: Doppler Lidar post-processing Wind velocity reconstruction Time gating Spectral analysis Averaging Frequency estimation V tm FFT Combinaison of several lines of sight with DBS, VAD modes Peak detect Centroid S FFT fdVr FFT FFT • Averagingwith 10000 pulses ( and  ) • Improveaccuracyfrom 1 to 0.01 m/s Time resolution varies from 1 to 10 s (Source Cramer-Rao Lower Bound theory)

  6. Agenda • Bac to basics: the Doppler lidar principle • Accuracy and availability of measurements • Operational applications • Conclusion

  7. Accuracy of Doppler lidars measurements • For meteorology, several intercomparisons since 2007 with radars, radiosoundings, sodars in the framework of WAVES project (US) and COST action EG-CLIMET (FUND and Lindenberg campaigns) 10’ average Std deviation Vertical Wind speed Wind speed • Lidar Accuracy on wind speed < 0.5 m/s • Model , Radiosoundings and radars showed bias • First use of Doppler lidars : Wind profiling Source EGCLIMET report TECO Conference 2012 - Bruxelles

  8. Availability of lidars measurements Looking vertically: 80% of availability at 800m 4 months in Winter in Germany Cumulative PDF for range Looking horizontally: WHY? 4 months in Summler/Autumn in France 80% of availability at 5 km TECO Conference 2012 - Bruxelles

  9. Back to Bac to basics: Interaction between light and particules The received signal willdepend on the aerosolsin the atmosphere (mass concentration, size, shape, type, opticalproperties), cloudsand rains! Can wecorrelate range availability to met data ? The Lidar equation is:

  10. Availability of lidars measurements Looking vertically: Many other parameters (rain, type of aerosols…) influence range Numerical simulations help to confirm these dependences Range 4 months in Winter in Germany Cloud height Looking horizontally: Range Range 4 months in Summer/Autumn in France RH Visibility

  11. Agenda • Bac to basics: the Doppler lidar principle • Availability and accuracy of measurements • Operational applications • Conclusion

  12. Operational uses for weather aviation Spatial Resolution (m) 1000 100 10 Time Resolution 1 s 1 min 10 min 1 hour

  13. Nice Airport location • Nice airport is nr 3 in France for the number of passengers • Complexity of the topographyaround the airport (mediterraneanSea, Alps, Var valley) • Complex Wind motions on final approach (wind reverses) Remotesensingismandary for measuringaround the airport (sea) Lidars are wellsuited in this case since main windhazardsoccuring in clearsky

  14. Wind shear situation in August 2011 • Windshears observed during wind reverse • WS event lasted 10 mn: complex wind structures MeteoFrance - 2011 Nice Experiment

  15. Storm event • Storm arrival from north-east observed on lidar scan at 21:00 • Heavy rains on airport at 22:00 whch reduced the lidar range temporarily (combination with X-band) MeteoFrance - 2011 Nice Experiment

  16. Storm event Météo-France - Nice2011 experiment Radial wind field Wind reconstruction method Wind barbs Magnitude wind field wind direction field

  17. WP6.8.1 WP12.2.2 SESAR Package12.2.2 • Development of a Wake Vortex Advisory System 12.2.2 executed in tight interaction with 6.8.1 operational project Thales Air Systems 09th of October 2012

  18. Vr + - - + Wake vortex tracking in 2011 • Many issues: • Duration of WVs (increase scan speed) • Real time monitoring • Groundeffect • Variety of take-off • Trajectories 9R 9L TAKE OFF LANDING CDG Airport - Paris

  19. Wake vortex tracking in 2011 • More than 200 wakes detected over the first campaign • Monitoring of wakes during takeoff / landing below the glide / on the runways • Necessity to monitor wakes in-ground effect but not out-of-ground effect • Many improvements have done to automatically and accurately detect WVs •  XP2 Campaign this year to validate the WVAS Detection of Wake Vortex the 16/05/2011 12h19 for a A380

  20. Conclusion • Doppler Lidars are ready for operationnal uses • The technology inside is based on reliable components • The core post-processing is simple, robust and accurate • Numerous campaigns have been realized in various conditions and for various purposes • Accuracy on wind speed below 0.5 m/s • Availability of lidars is satisfiying in the PBL even in Winter • Operationnal applications rush the needs: wind energy, weather aviation (wind hazards), meteorology

  21. Perspectives • ISO Standards for Doppler lidars have been engaged • Advanced meteorological products are available for wind shears and wake vortices (in development) • New Eu project called UFO for improving the radar/lidar solution for measuring wake vortices in real time

  22. Thankyou for your attentionlthobois@leosphere.com

  23. Annexes TECO 2012 in Brussels

  24. Accuracy of Doppler lidars measurements • In Wind energy, wind measurements must be very accurate in order to ensure the reliable investment of wind farm projects • Doppler lidars are usually compared to met mast Wind speed correlation at 100 meters Wind direction correlation at 100 meters  Wind accuracy proven of 0.1 m/s Source Riso DTU report TECO Conference 2012 - Bruxelles

  25. Accuracy of Doppler lidars measurements • For meteorology, several intercomparisons since 2007 with radars, radiosoundings, sodars in the framework of WAVES project (US) and COST action EG-CLIMET LINDENBERG campaign (1+4 months in Lindenberg, Germany) Source EGCLIMET presentation TECO Conference 2012 - Bruxelles

  26. Bac to basics: Determination of wind profile Electric current (ns-nol) MHz Signal, ns, THz Local Oscillator, nol, THz

  27. Availability of lidars measurements Looking horizontally: 4 month in Fall in France

  28. Wind Doppler lidar for meteorology Signal strength (CNR) Horizontal wind speed Vertical Turbulence

  29. Storm event in Aug 2011- Nice Airport Météo-France - Nice2011 experiment • Cold front coming from the North West forceast in the evening • In this summer thunder storm, heavy rains arrived at the airport one hour after seeing the cunum in the lidar scope

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