Calibration method for the lidar-observed stratospheric depolarization ratio in the presence of liquid aerosol particles

Adachi, Hiroshi; Shibata, Takashi; Iwasaka, Yasunobu; Fujiwara, Motowo

doi:10.1364/ao.40.006587

Cited by 35 publications

(34 citation statements)

References 24 publications

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“…Different PSC types, as observed by both lidar systems, have been classified according to the obtained R and d V values (see section 3 for details). For convenience, backscattering ratios R were replaced with the 1 2 1/R parameter to limit the R values in the range (0, 1) for a better graphic representation with the volume depolarization d V , as suggested by Adachi et al (2001), adopted by Adriani et al (2004), and applied by Massoli et al (2006).…”

Section: B Data Processingmentioning

confidence: 99%

Polar Stratospheric Cloud Observations in the 2006/07 Arctic Winter by Using an Improved Micropulse Lidar

Córdoba-Jabonero

Gil

Yela

et al. 2009

Journal of Atmospheric and Oceanic Technology

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The potential of a new improved version of micropulse lidar (MPL-4) on polar stratospheric cloud (PSC) detection is evaluated in the Arctic over Ny-Å lesund (798N, 128E), Norway. The campaign took place from January to February 2007 in the frame of the International Polar Year (IPY) activities. Collocated Alfred Wegener Institute (AWI) Koldewey Aerosol Raman Lidar (KARL) devoted to long-term Arctic PSC monitoring is used for validation purposes. PSC detection is based on lidar retrievals of both backscattering ratio R and volume depolarization ratio d V . Two episodes were unequivocally attributed to PSCs: 21-22 January and 5-6 February 2007, showing a good correlation between MPL-4 and KARL backscattering ratio datasets (mean correlation coefficient 5 0.92 6 0.03). PSC layered structures were characterized for four observational periods coincident with KARL measurements. Also, PSC type classification was determined depending on the retrieved R and d V values as compared with those obtained by KARL long-term Arctic PSC measurements. Tropospheric cloud cover from lidar observations and both ECMWF potential vorticity and temperature at 475 K, in addition to temperature profiles from AWI daily radiosoundings, are also reported. Height-resolved and temporal evolution of both PSC episodes obtained from MPL-4 measurements clearly show that MPL-4 is a suitable instrument to provide long-term PSC statistic monitoring in polar regions. These results are the first reported on PSC detection in the Arctic by using a low-energy and highly pulsed lidar operating on autonomous and full-time continuous mode MPL-4.

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Section: B Data Processingmentioning

confidence: 99%

Polar Stratospheric Cloud Observations in the 2006/07 Arctic Winter by Using an Improved Micropulse Lidar

Córdoba-Jabonero

Gil

Yela

et al. 2009

Journal of Atmospheric and Oceanic Technology

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“…We used the value of 0.49% for d m which depends on the wavelength and bandwidth of the measurement (the interference filter of FWHM = 1.17 nm utilized in this study). We corrected the measured d values to eliminate the depolarization components produced by the system [Adachi et al, 2001]. The value of d a is zero for homogenous spherical particles and substantially deviates from zero for nonspherical particles [e.g., Asano and Sato, 1980;Mishchenko and Hovenier, 1995].…”

Section: Raman Lidar Measurementsmentioning

confidence: 99%

Raman lidar and aircraft measurements of tropospheric aerosol particles during the Asian dust event over central Japan: Case study on 23 April 1996

et al. 2003

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[1] The vertical distributions of tropospheric aerosol properties were measured during the Asian dust event over central Japan (35°-36°N, 136°-137°E), using a ground-based Raman lidar and aircraft-based instruments on 23 April 1996. The lidar measured enhancements of aerosol backscattering below an altitude of 4 km and between 5 and 8 km where the total aerosol linear depolarization ratio showed peaks of 12-15% and the relative humidities were $30%. The aircraft measurements showed that the aerosol particles consisted primarily of irregularly shaped mineral dusts and sea salts with a mode radius (r m ) of $1 mm and sulfates with r m $ 0.1 mm over the measured height range of 0.6-5.5 km. Electron microscopic analyses suggest that $77% of the mineral particles were coated with a solution at 1.8 km and that the fraction of coated particles decreased with height. The aerosol backscattering coefficients (b a ), calculated from the airborne optical particle counter (OPC) data, were smaller than the lidar-derived values by $30% above 3.1 km and by $44% below that altitude. The difference was attributable to the horizontal and temporal inhomogeneities of the aerosol properties between the measurement sites and to the uncertainty in b a , particularly for the coarse particles calculated from the OPC data. The aerosol depolarization ratios (d a ) estimated from the OPC data showed the same increase as those obtained with the lidar above 4.1 km. This suggests that the proportion of backscattering by coarse particles to total particles primarily controlled the d a measured with the lidar in that region.

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“…Platt, 1977) or liquid-dropletonly stratospheric clouds (e.g. Adachi et al, 2001, requiring additionally a total backscattering ratio measurement). Bravo-Aranda et al (2016) and Freudenthaler (2016) analyze the effects of transmitter-receiver angular misalignment on uncertainties in the retrieved atmospheric depolarization values.…”

Section: Literature Review Of Depolarization Calibrationsmentioning

confidence: 99%

Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada

et al. 2017

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Abstract. 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.

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Calibration method for the lidar-observed stratospheric depolarization ratio in the presence of liquid aerosol particles

Cited by 35 publications

References 24 publications

Polar Stratospheric Cloud Observations in the 2006/07 Arctic Winter by Using an Improved Micropulse Lidar

Polar Stratospheric Cloud Observations in the 2006/07 Arctic Winter by Using an Improved Micropulse Lidar

Raman lidar and aircraft measurements of tropospheric aerosol particles during the Asian dust event over central Japan: Case study on 23 April 1996

Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada

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