Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada
The Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh–Mie–Raman lidar (CRL) at Eureka, Nunavut, has measured tropospheric clouds, aerosols, and water vapour since 2007. In remote and meteorologically significant locations, such as the Canadian High Arctic, the ability to...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-11-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/10/4253/2017/amt-10-4253-2017.pdf |
| _version_ | 1818683136193593344 |
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| author | E. M. McCullough E. M. McCullough R. J. Sica J. R. Drummond G. Nott G. Nott C. Perro C. P. Thackray J. Hopper J. Doyle T. J. Duck K. A. Walker |
| author_facet | E. M. McCullough E. M. McCullough R. J. Sica J. R. Drummond G. Nott G. Nott C. Perro C. P. Thackray J. Hopper J. Doyle T. J. Duck K. A. Walker |
| author_sort | E. M. McCullough |
| collection | DOAJ |
| description | The Canadian Network for the Detection of Atmospheric Change (CANDAC)
Rayleigh–Mie–Raman lidar (CRL) at Eureka, Nunavut, has measured
tropospheric clouds, aerosols, and water vapour since 2007. In remote and
meteorologically significant locations, such as the Canadian High Arctic, the
ability to add new measurement capability to an existing well-tested facility
is extremely valuable. In 2010, linear depolarization 532 nm
measurement hardware was installed in the lidar's receiver. To minimize
disruption in the existing lidar channels and to preserve their existing
characterization so far as is possible, the depolarization hardware was
placed near the end of the receiver cascade. The upstream optics already in
place were not optimized for preserving the polarization of received light.
Calibrations and Mueller matrix calculations are used to determine and
mitigate the contribution of these upstream optics on the depolarization
measurements. The results show that with appropriate calibration, indications
of cloud particle phase (ice vs. water) through the use of the depolarization
parameter are now possible to a precision of ±0.05 absolute uncertainty
( ≤ 10 % relative uncertainty) within clouds at time and altitude
resolutions of 5 min and 37.5 m respectively, with higher
precision and higher resolution possible in select cases. The uncertainty is
somewhat larger outside of clouds at the same altitude, typically with
absolute uncertainty ≤ 0.1. Monitoring changes in Arctic cloud
composition, including particle phase, is essential for an improved
understanding of the changing climate locally and globally. |
| first_indexed | 2024-12-17T10:29:56Z |
| format | Article |
| id | doaj.art-2de00d96e817422bb522e771428c324e |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-12-17T10:29:56Z |
| publishDate | 2017-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-2de00d96e817422bb522e771428c324e2022-12-21T21:52:33ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482017-11-01104253427710.5194/amt-10-4253-2017Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, CanadaE. M. McCullough0E. M. McCullough1R. J. Sica2J. R. Drummond3G. Nott4G. Nott5C. Perro6C. P. Thackray7J. Hopper8J. Doyle9T. J. Duck10K. A. Walker11Department of Physics and Astronomy, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 3K7, CanadaDepartment of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Rd., P.O. Box 15000, Halifax, NS, B3H 4R2, CanadaDepartment of Physics and Astronomy, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 3K7, CanadaDepartment of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Rd., P.O. Box 15000, Halifax, NS, B3H 4R2, CanadaDepartment of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Rd., P.O. Box 15000, Halifax, NS, B3H 4R2, Canadapresent address: Facility for Airborne Atmospheric Measurements, Building 146, Cranfield University, Cranfield, MK43 0AL, UKDepartment of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Rd., P.O. Box 15000, Halifax, NS, B3H 4R2, CanadaDepartment of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Rd., P.O. Box 15000, Halifax, NS, B3H 4R2, CanadaDepartment of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Rd., P.O. Box 15000, Halifax, NS, B3H 4R2, CanadaDepartment of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Rd., P.O. Box 15000, Halifax, NS, B3H 4R2, CanadaDepartment of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Rd., P.O. Box 15000, Halifax, NS, B3H 4R2, CanadaDepartment of Physics, University of Toronto, 60 St. George St., Toronto, Ontario, M5S 1A7, CanadaThe Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh–Mie–Raman lidar (CRL) at Eureka, Nunavut, has measured tropospheric clouds, aerosols, and water vapour since 2007. In remote and meteorologically significant locations, such as the Canadian High Arctic, the ability to add new measurement capability to an existing well-tested facility is extremely valuable. In 2010, linear depolarization 532 nm measurement hardware was installed in the lidar's receiver. To minimize disruption in the existing lidar channels and to preserve their existing characterization so far as is possible, the depolarization hardware was placed near the end of the receiver cascade. The upstream optics already in place were not optimized for preserving the polarization of received light. Calibrations and Mueller matrix calculations are used to determine and mitigate the contribution of these upstream optics on the depolarization measurements. The results show that with appropriate calibration, indications of cloud particle phase (ice vs. water) through the use of the depolarization parameter are now possible to a precision of ±0.05 absolute uncertainty ( ≤ 10 % relative uncertainty) within clouds at time and altitude resolutions of 5 min and 37.5 m respectively, with higher precision and higher resolution possible in select cases. The uncertainty is somewhat larger outside of clouds at the same altitude, typically with absolute uncertainty ≤ 0.1. Monitoring changes in Arctic cloud composition, including particle phase, is essential for an improved understanding of the changing climate locally and globally.https://www.atmos-meas-tech.net/10/4253/2017/amt-10-4253-2017.pdf |
| spellingShingle | E. M. McCullough E. M. McCullough R. J. Sica J. R. Drummond G. Nott G. Nott C. Perro C. P. Thackray J. Hopper J. Doyle T. J. Duck K. A. Walker Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada Atmospheric Measurement Techniques |
| title | Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada |
| title_full | Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada |
| title_fullStr | Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada |
| title_full_unstemmed | Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada |
| title_short | Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada |
| title_sort | depolarization calibration and measurements using the candac rayleigh mie raman lidar at eureka canada |
| url | https://www.atmos-meas-tech.net/10/4253/2017/amt-10-4253-2017.pdf |
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