1. Lidar overlap control as a mean for extended measurement reliability Ilya Serikov, Holger Linné, Friedhelm Jansen, Björn Brügmann, Monika Pfeiffer, Jens Bösenberg Max Planck Institute for Meteorology, Hamburg

2. Outline a) The overlap control issues: An approach to measure overlap function Optical scrambler as a solution for identical overlap Overlap correction in extinction retrieval b) Lidar / Ceilometer comparison * The subject presented is illustrated on the data collected with one of two Raman lidars of Max Planck Institute for Meteorology (Hamburg) deployed on Deebles Point, Barbados (59.43W 13.16N) since 04.04.2010

3. http://pvcdrom.pveducation.org/SUNLIGHT/SUNCALC.HTM Sun's azimuth and elevation angles, 2010.07.15 (projection onto a two-dimensional plane)

4. Principle optical layout

5. Telescope assignment “close” range Ø 2 cm “far” range Ø 40 cm “near” range Ø 15 cm

6. Overlap function & lidar returns

7. ALOMAR (Norway), 2009.11.01, 03:00-06:00 UTC Overlap function, far range telescope

8. Overlap function, near range telescope ALOMAR (Norway), 2009.11.01, 03:00-06:00 UTC

9. Particle backscatter 532nm, far & close range resolution: 30 minutes, 60÷180 meters

10. Particle backscatter 532nm, far & close range resolution: 30 minutes, 60÷180 meters

11. Particle backscatter 532nm, far & close range resolution: 2 minutes, 60 meters

12. Particle backscatter 532nm, far & close range resolution: 2 minutes, 60 meters

13. Particle backscatter 355nm, far & near range resolution: 2 minutes, 60 meters

14. http://pvcdrom.pveducation.org/SUNLIGHT/SUNCALC.HTM Sun's azimuth and elevation angles, 2010.04.12 (projection onto a two-dimensional plane) Lidar FOV

15. Raman lidar returns, 532nm, near & far range resolution: signals: 40 minutes, 60m overlap: 3 hours, 60m÷5km

16. Statistical uncertainty of lidar returns, near & far range

17. Raman lidar returns, 532nm, near & far range resolution: signals: 40 minutes, 60m overlap: 3 hours, 60m÷5km

18. Statistical uncertainty of lidar returns, near & far range

19. Particle extinction, 532nm, near & far range resolution: 40 minutes, 0.18÷3km

20. Overlap function, far range telescope, 532nm, 10.04.12 resolution: 3 hours, 60m÷5km

21. Overlap function, far range telescope, 532nm, 10.04.12 resolution: 3 hours, 60m÷5km

22. Particle extinction, 532nm, near & far range resolution: extinction: 40 minutes, 0.18÷3km overlap: 3 hours, 60m÷5km

23. Particle extinction, 532nm, near & far range resolution: extinction: 40 minutes, 0.18÷3km overlap: 3 hours, 60m÷5km

24. Aerosol optical depth: lidar (0.6-12km) / sun-photometer We thank J. M. Prospero for establishing and maintaining the AERONET site at Ragged Point, Barbados.

25. Aerosol optical depth: lidar (0-12km) / sun-photometer We thank J. M. Prospero for establishing and maintaining the AERONET site at Ragged Point, Barbados.

26. Aerosol optical depth: lidar (0.6-12km) mask: particle backscatter > 2 / (Mm sr)

27. Overlap function, far range telescope, 532nm, 10.07.15 resolution: 3 hours, 60m÷5km

28. Raman lidar returns, 532nm, near & far range resolution: signals: 40 minutes, 60m overlap: 3 hours, 60m÷5km

29. Particle extinction, 532nm, near & far range resolution: extinction: 40 minutes, 0.18÷3km overlap: 3 hours, 60m÷5km

30. Particle extinction, 355nm, near & far range resolution: 40 minutes, 0.18÷3km

31. resolution: 30 minutes, 0.18÷3km Particle backscatter & extinction 532nm, far range

32. resolution: 30 minutes, 0.18÷1.8km Particle backscatter & extinction 532nm, near range

33. resolution: 30 minutes, 180m Particle backscatter & extinction 532nm, close range

34. resolution: 30 minutes, 0.18÷3km Particle backscatter & extinction 355nm, far range

35. resolution: 30 minutes, 0.18÷1.8km Particle backscatter & extinction 355nm, near range

36. resolution: 30 minutes, 180m Particle backscatter & extinction 355nm, close range

37. Aerosol optical depth: lidar (0.6-12km) / sun-photometer We thank J. M. Prospero for establishing and maintaining the AERONET site at Ragged Point, Barbados.

38. Aerosol optical depth: lidar (0-12km) / sun-photometer We thank J. M. Prospero for establishing and maintaining the AERONET site at Ragged Point, Barbados.

39. Attenuated backscatter 1064nm, far/near-range resolution: 2 minutes, 60 meters

40. Aerosol optical depth: lidar (0.6-12km) mask: particle backscatter > 2 / (Mm sr)

41. Conclusion a) optical scrambling allows no overlap-depending artefacts in lidar products derived through a signal ratio b) measuring the overlap (continuously) allows extending the system reliability for extinction retrieval in other words: the lidar may be misaligned to some (even quite significant) extent, we should just know how much is it by measuring the overlap function.

42. Lidar / Ceilometer comparion

43. Lidar: attenuated backscatter 1064nm resolution: 2 minutes, 60 meters Normalized attenuated backscatter

44. resolution: lidar: 2min & 60m; ceilometer: 10min & 120m Attenuated backscatter 1064nm, lidar & “Jenoptik 15k”

45. resolution: lidar: 2min & 60m; ceilometer: 10min & 120m Attenuated backscatter 1064nm, lidar & “Jenoptik 15k-x”

46. Attenuated backscatter 1064nm, lidar & “Jenoptik 15k”

47. Acknowledgments: We thank Dr. David A. Farrell (the Caribbean Institute for Meteorology and Hydrology) and his research team, especially Marvin R. Forde, for helping us establishing and maintaining the site.

48. Thank you!