Lidar studies of the polar troposphere

Nott, G. J.; Duck, Thomas J.

doi:10.1002/met.289

Cited by 19 publications

(20 citation statements)

References 162 publications

(241 reference statements)

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“…The inversion technique of Klett (1981) is used to calculate total scattering coefficient as described by Neely et al (2013). A lidar ratio of 10 is assumed, following the results of Hoffmann et al (2009) and review of Nott and Duck (2011) and references therein, to convert the total extinction derived by the Klett inversion to total backscattering coefficient.…”

Section: Processing Methodsmentioning

confidence: 99%

“…Nott and Duck (2011) and references therein lists many other groundbased lidar deployment sites in the polar regions such as Syowa, Antarctica; South Pole, Antarctica; Eureka, Canada; and Barrow, Alaska. Further, the CALIOP lidar on board the CALIPSO satellite uses analog detection, and regularly observes the polar regions (Winker et al, 2009).…”

Section: Comparisons With Non-lidar Data Sourcesmentioning

confidence: 99%

“…Nott and Duck (2011) and references therein summarize more than a dozen lidar deployment sites in the Arctic and Antarctic. Polarimetric lidar data are particularly useful for cloud and aerosol studies to determine properties such as cloud phase, cloud base height, and particle orientation, as well as for broad aerosol classifications (Schotland et al, 1971;Measures, 1984;Sassen, 1 This work uses the definition of mixed-phase clouds presented by Shupe et al (2008), where a mixed-phase cloud is defined as a cloud system containing both liquid and ice water that interact via microphysical processes.…”

Section: Introductionmentioning

confidence: 99%

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Improved cloud-phase determination of low-level liquid and mixed-phase clouds by enhanced polarimetric lidar

et al. 2018

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Abstract. The unambiguous retrieval of cloud phase from polarimetric lidar observations is dependent on the assumption that only cloud scattering processes affect polarization measurements. A systematic bias of the traditional lidar depolarization ratio can occur due to a lidar system's inability to accurately measure the entire backscattered signal dynamic range, and these biases are not always identifiable in traditional polarimetric lidar systems. This results in a misidentification of liquid water in clouds as ice, which has broad implications on evaluating surface energy budgets. The Clouds Aerosol Polarization and Backscatter Lidar at Summit, Greenland employs multiple planes of linear polarization, and photon counting and analog detection schemes, to self evaluate, correct, and optimize signal combinations to improve cloud classification. Using novel measurements of diattenuation that are sensitive to both horizontally oriented ice crystals and counting system nonlinear effects, unambiguous measurements are possible by over constraining polarization measurements. This overdetermined capability for cloud-phase determination allows for system errors to be identified and quantified in terms of their impact on cloud properties. It is shown that lidar system dynamic range effects can cause errors in cloud-phase fractional occurrence estimates on the order of 30 % causing errors in attribution of cloud radiative effects on the order of 10-30 %. This paper presents a method to identify and remove lidar system effects from atmospheric polarization measurements and uses colocated sensors at Summit to evaluate this method. Enhanced measurements are achieved in this work with non-orthogonal polarization retrievals as well as analog and photon counting detection facilitating a more complete attribution of radiative effects linked to cloud properties.

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Section: Processing Methodsmentioning

confidence: 99%

Section: Comparisons With Non-lidar Data Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved cloud-phase determination of low-level liquid and mixed-phase clouds by enhanced polarimetric lidar

et al. 2018

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“…CAPABL was deployed to Summit in June of 2010 and has run continuously (24-h operation) since that time except for short periods of maintenance and further instrument development. CAPABL is the newest addition to the Arctic network of lidars and because of its location on top of the GIS it is one of the few lidars that will be minimally impacted by regional change (Nott and Duck 2011).…”

Section: Introductionmentioning

confidence: 99%

Polarization Lidar at Summit, Greenland, for the Detection of Cloud Phase and Particle Orientation

Neely

Hayman

Stillwell

et al. 2013

Journal of Atmospheric and Oceanic Technology

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Accurate measurements of cloud properties are necessary to document the full range of cloud conditions and characteristics. The Cloud, Aerosol Polarization and Backscatter Lidar (CAPABL) has been developed to address this need by measuring depolarization, particle orientation, and the backscatter of clouds and aerosols. The lidar is located at Summit, Greenland (72.68N, 38.58W; 3200 m MSL), as part of the Integrated Characterization of Energy, Clouds, Atmospheric State, and Precipitation at Summit Project and NOAA's Earth System Research Laboratory's Global Monitoring Division's lidar network. Here, the instrument is described with particular emphasis placed upon the implementation of new polarization methods developed to measure particle orientation and improve the overall accuracy of lidar depolarization measurements. Initial results from the lidar are also shown to demonstrate the ability of the lidar to observe cloud properties.

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“…Nott and Duck (2011) and references therein summarize more than a dozen lidar deployment sites in the Arctic and Antarctic. Polarimetric lidar data is particularly useful for cloud and aerosol studies to determine properties such as cloud phase, cloud base height, particle 25 orientation, and for broad aerosol classifications (Schotland et al, 1971;Measures, 1984;Sassen, 1991;Kaul et al, 2004;Fujii and Fukuchi, 2005;Weitkamp, 2005;Freudenthaler et al, 2009;Hayman and Thayer, 2012;Groß et al, 2015).…”

mentioning

confidence: 99%

Improved Cloud Phase Determination of Low Level Liquid and Mixed Phase Clouds by Enhanced Polarimetric Lidar

Stillwell¹,

Neely²,

Thayer³

et al. 2017

Preprint

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Abstract. The unambiguous retrieval of cloud phase from polarimetric lidar observations is dependent on the assumption that only cloud scattering processes affect polarization measurements. A systematic bias of the traditional lidar depolarization ratio can occur due to a lidar system's inability to accurately measure the entire backscattered signal dynamic range, and these biases are not always identifiable in traditional polarimetric lidar systems. This results in a misidentification of liquid water in clouds as ice, which has broad implications on evaluating surface energy budgets. The Clouds Aerosol Polarization and Backscatter 5Lidar at Summit, Greenland employs multiple planes of linear polarization, and photon counting and analog detection schemes, to self evaluate, correct, and optimize signal combinations to improve cloud classification. Using novel measurements of diattenuation that are sensitive to both horizontally oriented ice crystals and counting system non-linear effects, unambiguous measurements are possible by over constraining polarization measurements. This overdetermined capability for cloud phase determination allows for system errors to be identified and quantified in terms of their impact on cloud properties. It is shown 10 that lidar system dynamic range effects can cause errors in cloud phase fractional occurrence estimates on the order of 30% causing errors in attribution of cloud radiative effects on the order of 10%-30%. This paper presents a method to identify and remove lidar system effects from atmospheric polarization measurements and uses co-located sensors at Summit to validate this method.1 Atmos. Meas. Tech. Discuss., https://doi

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Lidar studies of the polar troposphere

Cited by 19 publications

References 162 publications

Improved cloud-phase determination of low-level liquid and mixed-phase clouds by enhanced polarimetric lidar

Improved cloud-phase determination of low-level liquid and mixed-phase clouds by enhanced polarimetric lidar

Polarization Lidar at Summit, Greenland, for the Detection of Cloud Phase and Particle Orientation

Improved Cloud Phase Determination of Low Level Liquid and Mixed Phase Clouds by Enhanced Polarimetric Lidar

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