Earlinet single calculus chain: new products overview

The Single Calculus Chain (SCC) is an automatic and flexible tool to analyze raw lidar data using EARLINET quality assured retrieval algorithms. It has been already demonstrated the SCC can retrieve reliable aerosol backscatter and extinction coefficient profiles for different lidar systems. In this paper we provide an overview of new SCC products like particle linear depolarization ratio, cloud masking, aerosol layering allowing relevant improvements in the atmospheric aerosol characterization.

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Polarization lidar for atmospheric monitoring

EPJ Web of Conferences ◽

10.1051/epjconf/201817605052 ◽

2018 ◽

Vol 176 ◽

pp. 05052

Author(s):

Qiaojun Liu ◽

Chengxuan Wu ◽

Andrew Yuk Sun Cheng ◽

Zhangjun Wang ◽

Xiangqian Meng ◽

...

Keyword(s):

Extinction Coefficient ◽

Atmospheric Aerosol ◽

Global Climate ◽

Aerosol Extinction ◽

Depolarization Ratio ◽

Backscattering Coefficient ◽

Lidar System ◽

Weather Changes ◽

And Inversion ◽

Aerosol Extinction Coefficient

Aerosol plays an important role in global climate and weather changes. Polarization lidar captures parallel and perpendicular signals from atmosphere to research aerosols. The lidar system we used has three emission wavelengths and could obtain the atmospheric aerosol extinction coefficient, backscattering coefficient and depolarization ratio. In this paper, the design of the lidar is described. The methods of data acquisition and inversion are given. Some recent results are presented.

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Studies on Aerosol Optical Properties at High Altitude Station in Western Himalayas Using Raman Lidar

EPJ Web of Conferences ◽

10.1051/epjconf/202023702034 ◽

2020 ◽

Vol 237 ◽

pp. 02034

Author(s):

Shishir Kumar Singh ◽

Jaswant ◽

S.R. Radhakrishnan ◽

Davender Sethi ◽

Chhemendra Sharma

Keyword(s):

Optical Properties ◽

Extinction Coefficient ◽

Spherical Particles ◽

Western Himalayas ◽

Depolarization Ratio ◽

Raman Lidar ◽

Inversion Algorithm ◽

Backscatter Coefficient ◽

Aerosol Optical Properties ◽

Linear Depolarization Ratio

The aerosol optical properties have been investigated using the Raman lidar system for the month of November 2018 at the western Himalayan station of Palampur. Before deriving the optical properties, the lidar data has been applied with initial pre-processing such as Dead time correction, atmospheric noise correction, temporal and spatial averaging, range correction, gluing etc. The optical properties such as backscatter coefficient, extinction coefficient and linear depolarization ratio have been derived by using the inversion algorithm proposed by Fernald. The results show that the backscatter coefficient was found in the range from 9.00E-9 m−1sr−1 to 4.97E-6 m−1sr−1 and the extinction coefficient was found in the range from 3.16E-7m-1 to 1.74E-4m-1. The Linear depolarization ratio was in the range from 0.0179 to 0.621 with lower values at near heights suggesting the dominance of spherical particles at the lower heights. We have also observed a cloud layer at a height of 9.5 km to 12.1 km with high depolarization ratio during the observation period on 22/11/2018.

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Backscattering linear depolarization ratio of laboratory generated ice clouds composed of pristine and complex-shaped ice crystals

Conference on Electromagnetic and Light Scattering ◽

10.1615/ichmt.2007.confelectromagligscat.510 ◽

2007 ◽

Cited By ~ 1

Author(s):

Martin Schnaiter ◽

Roland Schon ◽

Ottmar Mohler ◽

Harald Saathoff ◽

Robert Wagner

Keyword(s):

Ice Crystals ◽

Depolarization Ratio ◽

Ice Clouds ◽

Linear Depolarization Ratio

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Fully automated analysis of space-based lidar data: an overview of the CALIPSO retrieval algorithms and data products

10.1117/12.572024 ◽

2004 ◽

Cited By ~ 194

Author(s):

Mark A. Vaughan ◽

Stuart A. Young ◽

David M. Winker ◽

Kathleen A. Powell ◽

Ali H. Omar ◽

...

Keyword(s):

Automated Analysis ◽

Lidar Data ◽

Retrieval Algorithms ◽

Data Products

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Accurate spectrally modulating polarimeters for atmospheric aerosol characterization

10.1117/12.2188024 ◽

2015 ◽

Cited By ~ 6

Author(s):

Jeroen H. H. Rietjens ◽

Martijn Smit ◽

Gerard van Harten ◽

Antonio Di Noia ◽

Otto P. Hasekamp ◽

...

Keyword(s):

Atmospheric Aerosol ◽

Aerosol Characterization

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Benefit of depolarization ratio at λ = 1064 nm for the retrieval of the aerosol microphysics from lidar measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-7-3773-2014 ◽

2014 ◽

Vol 7 (11) ◽

pp. 3773-3781 ◽

Cited By ~ 13

Author(s):

J. Gasteiger ◽

V. Freudenthaler

Keyword(s):

Optical Properties ◽

Mass Concentration ◽

Volcanic Ash ◽

Single Scattering ◽

Depolarization Ratio ◽

Complex Relation ◽

Microphysical Properties ◽

Lidar Measurements ◽

Increased Sensitivity ◽

Linear Depolarization Ratio

Abstract. A better quantification of aerosol properties is required for improving the modelling of aerosol effects on weather and climate. This task is methodologically demanding due to the diversity of the microphysical properties of aerosols and the complex relation between their microphysical and optical properties. Advanced lidar systems provide spatially and temporally resolved information on the aerosol optical properties that is sufficient for the retrieval of important aerosol microphysical properties. Recently, the mass concentration of transported volcanic ash, which is relevant for the flight safety of aeroplanes, was retrieved from measurements of such lidar systems in southern Germany. The relative uncertainty of the retrieved mass concentration was on the order of ±50%. The present study investigates improvements of the retrieval accuracy when the capability of measuring the linear depolarization ratio at 1064 nm is added to the lidar setup. The lidar setups under investigation are based on those of MULIS and POLIS of the Ludwig-Maximilians-Universität in Munich (Germany) which measure the linear depolarization ratio at 355 and 532 nm with high accuracy. The improvements are determined by comparing uncertainties from retrievals applied to simulated measurements of this lidar setup with uncertainties obtained when the depolarization at 1064 nm is added to this setup. The simulated measurements are based on real lidar measurements of transported Eyjafjallajökull volcano ash. It is found that additional 1064 nm depolarization measurements significantly reduce the uncertainty of the retrieved mass concentration and effective particle size. This significant improvement in accuracy is the result of the increased sensitivity of the lidar setup to larger particles. The size dependence of the depolarization does not vary strongly with refractive index, thus we expect similar benefits for the retrieval in case of measurements of other volcanic ash compositions and also for transported desert dust. For the retrieval of the single scattering albedo, which is relevant to the radiative transfer in aerosol layers, no significant improvements were found.

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An analysis of the influence of hydrometeors on the linear depolarization ratio and differential reflectivity of the radar signals

Proceedings of Tomsk State University of Control Systems and Radioelectronics ◽

10.21293/1818-0442-2017-20-2-28-32 ◽

2017 ◽

Vol 20 (2) ◽

pp. 28-32

Author(s):

E.V. Masalov ◽

◽

N.N. Krivin ◽

K.V. Kokoulin ◽

◽

...

Keyword(s):

Depolarization Ratio ◽

Radar Signals ◽

Linear Depolarization Ratio ◽

Differential Reflectivity

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Airborne measurements of aerosol optical properties related to early spring transport of mid-latitude sources into the Arctic

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-5011-2010 ◽

2010 ◽

Vol 10 (11) ◽

pp. 5011-5030 ◽

Cited By ~ 48

Author(s):

R. A. de Villiers ◽

G. Ancellet ◽

J. Pelon ◽

B. Quennehen ◽

A. Schwarzenboeck ◽

...

Keyword(s):

Optical Properties ◽

The Arctic ◽

Depolarization Ratio ◽

Aerosol Optical Properties ◽

Accumulation Mode ◽

Color Ratio ◽

Aerosol Sources ◽

Aerosol Backscatter ◽

532 Nm

Abstract. Airborne lidar and in-situ measurements of the aerosol properties were conducted between Svalbard Island and Scandinavia in April 2008. Evidence of aerosol transport from Europe and Asia is given. The analysis of the aerosol optical properties based on a multiwavelength lidar (355, 532, 1064 nm) including volume depolarization at 355 nm aims at distinguishing the role of the different aerosol sources (Siberian wild fires, Eastern Asia and European anthropogenic emissions). Combining, first aircraft measurements, second FLEXPART simulations with a calculation of the PBL air fraction originating from the three different mid-latitude source regions, and third level-2 CALIPSO data products (i.e. backscatter coefficient 532 nm,volume depolarization and color ratio between 1064 and 532 nm in aerosol layers) along the transport pathways, appears a valuable approach to identify the role of the different aerosol sources even after a transport time larger than 4 days. Optical depth of the aerosol layers are always rather small (<4%) while transported over the Arctic and ratio of the total attenuated backscatter (i.e. including molecular contribution) provide more stable result than conventional aerosol backscatter ratio. Above Asia, CALIPSO data indicate more depolarization (up to 15%) and largest color ratio (>0.5) for the northeastern Asia emissions (i.e. an expected mixture of Asian pollution and dust), while low depolarization together with smaller and quasi constant color ratio (≈0.3) are observed for the Siberian biomass burning emissions. A similar difference is visible between two layers observed by the aircraft above Scandinavia. The analysis of the time evolution of the aerosol optical properties revealed by CALIPSO between Asia and Scandinavia shows a gradual decrease of the aerosol backscatter, depolarization ratio and color ratio which suggests the removal of the largest particles in the accumulation mode. A similar study conducted for a European plume has shown aerosol optical properties intermediate between the two Asian sources with color ratio never exceeding 0.4 and moderate depolarization ratio being always less than 8%, i.e. less aerosol from the accumulation mode.

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Benefit of depolarization ratio at λ = 1064 nm for the retrieval of the aerosol microphysics from lidar measurements

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-5095-2014 ◽

2014 ◽

Vol 7 (5) ◽

pp. 5095-5115

Author(s):

J. Gasteiger ◽

V. Freudenthaler

Keyword(s):

Optical Properties ◽

Mass Concentration ◽

Single Scattering ◽

Sufficient Information ◽

Depolarization Ratio ◽

Aerosol Composition ◽

Microphysical Properties ◽

Lidar Measurements ◽

Increased Sensitivity ◽

Linear Depolarization Ratio

Abstract. A better quantification of aerosol microphysical and optical properties is required to improve the modelling of aerosol effects on weather and climate. This task is methodologically demanding due to the huge diversity of aerosol composition and of their shape and size distribution, and due to the complexity of the relation between the microphysical and optical properties. Lidar remote sensing is a valuable tool to gain spatially and temporally resolved information on aerosol properties. Advanced lidar systems provide sufficient information on the aerosol optical properties for the retrieval of important aerosol microphysical properties. Recently, the mass concentration of transported volcanic ash, which is relevant for the flight safety of airplanes, was retrieved from measurements of such lidar systems in Southern Germany. The relative uncertainty of the retrieved mass concentration was on the order of ±50%. The present study investigates improvements of the retrieval accuracy when the capability of measuring the linear depolarization ratio at 1064 nm is added to the lidar setup. The lidar setups under investigation are based on the setup of MULIS and POLIS of the LMU in Munich which measure the linear depolarization ratio at 355 nm and 532 nm with high accuracy. By comparing results of retrievals applied to simulated lidar measurements with and without the depolarization at 1064 nm it is found that the availability of 1064 nm depolarization measurements reduces the uncertainty of the retrieved mass concentration and effective particle size by a factor of about 2–3. This significant improvement in accuracy is the result of the increased sensitivity of the lidar setup to larger particles. However, the retrieval of the single scattering albedo, which is relevant for the radiative transfer in aerosol layers, does hardly benefit from the availability of 1064 nm depolarization measurements.

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