Post on 24-Dec-2015
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
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
http://pvcdrom.pveducation.org/SUNLIGHT/SUNCALC.HTM
Sun's azimuth and elevation angles, 2010.07.15(projection onto a two-dimensional plane)
Principle optical layout
Telescope assignment
“close” rangeØ 2 cm
“far” rangeØ 40 cm
“near” rangeØ 15 cm
0.01 0.1 1 100
0.2
0.4
0.6
0.8
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Overlap function & lidar returns
0.01 0.1 1 100.001
0.01
0.1
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Far rangeNear rangeShort range
Height, km
Nor
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ALOMAR (Norway), 2009.11.01, 03:00-06:00 UTC
Overlap function, far range telescope
Overlap function, near range telescope
ALOMAR (Norway), 2009.11.01, 03:00-06:00 UTC
Particle backscatter 532nm, far & close range
resolution: 30 minutes, 60÷180 meters
Particle backscatter 532nm, far & close range
resolution: 30 minutes, 60÷180 meters
Particle backscatter 532nm, far & close range
resolution: 2 minutes, 60 meters
Particle backscatter 532nm, far & close range
resolution: 2 minutes, 60 meters
Particle backscatter 355nm, far & near range
resolution: 2 minutes, 60 meters
http://pvcdrom.pveducation.org/SUNLIGHT/SUNCALC.HTM
Sun's azimuth and elevation angles, 2010.04.12(projection onto a two-dimensional plane)
Lidar
FOV
Raman lidar returns, 532nm, near & far range
resolution: signals: 40 minutes, 60m overlap: 3 hours, 60m÷5km
Statistical uncertainty of lidar returns, near & far range
Raman lidar returns, 532nm, near & far range
resolution: signals: 40 minutes, 60m overlap: 3 hours, 60m÷5km
Statistical uncertainty of lidar returns, near & far range
Particle extinction, 532nm, near & far range
resolution: 40 minutes, 0.18÷3km
Overlap function, far range telescope, 532nm, 10.04.12
resolution: 3 hours, 60m÷5km
Overlap function, far range telescope, 532nm, 10.04.12
resolution: 3 hours, 60m÷5km
Particle extinction, 532nm, near & far range
resolution: extinction: 40 minutes, 0.18÷3km overlap: 3 hours, 60m÷5km
Particle extinction, 532nm, near & far range
resolution: extinction: 40 minutes, 0.18÷3km overlap: 3 hours, 60m÷5km
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.
Aerosol optical depth: lidar (0-12km) / sun-photometer
We thank J. M. Prospero for establishing and maintaining the AERONET site at Ragged Point, Barbados.
Aerosol optical depth: lidar (0.6-12km)
mask: particle backscatter > 2 / (Mm sr)
Overlap function, far range telescope, 532nm, 10.07.15
resolution: 3 hours, 60m÷5km
Raman lidar returns, 532nm, near & far range
resolution: signals: 40 minutes, 60m overlap: 3 hours, 60m÷5km
Particle extinction, 532nm, near & far range
resolution: extinction: 40 minutes, 0.18÷3km overlap: 3 hours, 60m÷5km
Particle extinction, 355nm, near & far range
resolution: 40 minutes, 0.18÷3km
resolution: 30 minutes, 0.18÷3km
Particle backscatter & extinction 532nm, far range
resolution: 30 minutes, 0.18÷1.8km
Particle backscatter & extinction 532nm, near range
resolution: 30 minutes, 180m
Particle backscatter & extinction 532nm, close range
resolution: 30 minutes, 0.18÷3km
Particle backscatter & extinction 355nm, far range
resolution: 30 minutes, 0.18÷1.8km
Particle backscatter & extinction 355nm, near range
resolution: 30 minutes, 180m
Particle backscatter & extinction 355nm, close range
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.
Aerosol optical depth: lidar (0-12km) / sun-photometer
We thank J. M. Prospero for establishing and maintaining the AERONET site at Ragged Point, Barbados.
Attenuated backscatter 1064nm, far/near-range
resolution: 2 minutes, 60 meters
Aerosol optical depth: lidar (0.6-12km)
mask: particle backscatter > 2 / (Mm sr)
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 retrievalin 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.
Lidar / Ceilometer comparion
Lidar: attenuated backscatter 1064nm
resolution: 2 minutes, 60 meters
No
rma
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resolution: lidar: 2min & 60m; ceilometer: 10min & 120m
Attenuated backscatter 1064nm, lidar & “Jenoptik 15k”
resolution: lidar: 2min & 60m; ceilometer: 10min & 120m
Attenuated backscatter 1064nm, lidar & “Jenoptik 15k-x”
Attenuated backscatter 1064nm, lidar & “Jenoptik 15k”
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.
Thank you!