The eVe reference polarisation lidar system for Cal/Val of Aeolus L2A product

Abstract. The eVe dual-laser/dual-telescope lidar system is briefly given here, focusing on the optical and mechanical parts of system’s emission and receiver units. The compact design of linear/circular emission unit along with the linear/circular analyser in the receiver unit, allows eVe to simultaneously reproduce the operation of the ALADIN lidar on board Aeolus as well as the operation of a traditional ground-based polarisation lidar system with linear emission. As such, eVe lidar aims to provide: (a) ground reference measurements for the validation of the Aeolus L2A aerosol products, and (b) the atmospheric conditions for which linear polarisation lidar systems can be considered for Aeolus L2A validation, by identifying any possible biases arisen from the different polarisation state in the emission between ALADIN and these systems, and the detection of only the co-polar component of the returned signal from ALADIN for the L2A products retrieval. In addition, a brief description is given concerning the polarisation calibration techniques that are applied in the system, as well as the developed software for the analysis of the collected signals and the retrieval of the optical products. More specifically, the system’s dual configuration enables the retrieval of the optical properties of particle backscatter and extinction coefficients originating from the two different polarisation states of the emission, the linear and circular depolarisation ratios, as well as the direct calculation of the Aeolus like backscatter coefficient, i.e., the backscatter coefficient that Aeolus would measure from ground. Two cases, one with slightly-depolarising particles and one with moderately-depolarising particles, were selected from the first conducted measurements of eVe in Athens, in order to give a glimpse of the system’s capabilities. In the slightly depolarising scene, the Aeolus like backscatter coefficient agrees well with the actual backscatter coefficient, which is also true when non-depolarising particles are present. The agreement however fades out for strongly depolarising scenes, where an underestimation of ~17 % of the Aeolus like backscatter coefficient is observed when moderately-depolarising particles are probed.

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The ESA-EVE Polarization Lidar for Assessing the Aeolus Aerosol Product Perfomance

EPJ Web of Conferences ◽

10.1051/epjconf/202023707025 ◽

2020 ◽

Vol 237 ◽

pp. 07025

Author(s):

Peristera Paschou ◽

Emmanouil Proestakis ◽

Alexandra Tsekeri ◽

Nikos Siomos ◽

Antonis Gkikas ◽

...

Keyword(s):

Spherical Particles ◽

Polar Component ◽

Doppler Lidar ◽

Backscatter Coefficient ◽

Lidar System ◽

Ground Based Lidar ◽

Reference Measurements ◽

Aerosol Backscatter ◽

Quality Assessment And Improvement ◽

Polarized Radiation

We present the EVE lidar concept, a combined linear/circular polarization system, tailored to evaluate the spaceborne ALADIN Doppler lidar system aerosol retrievals. EVE, currently under development, aims to provide the ESA-Aeolus mission with a flexible, mobile reference ground-based lidar system capable of providing well-characterized fiducial reference measurements of aerosol optical properties. Since ALADIN detects only the co-polar component of the backscattered circularly polarized radiation, a portion of the received radiation gets lost, leading to an un-derestimation of the backscatter coefficient and the circular depolarization ratio in strongly depolarizing scenes with non-spherical particles. The main focus of the new EVE lidar is to quantify these uncertainties and to evaluate aerosol backscatter/extinction retrievals for Aeolus, and later also for EarthCARE product validation, quality assessment and improvement.

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EVE polarization lidar: ESA’s ground reference system for Aeolus L2A products Cal/Val

10.5194/egusphere-egu21-9570 ◽

2021 ◽

Author(s):

Peristera Paschou ◽

Nikolaos Siomos ◽

Vassilis Amiridis ◽

Volker Freudenthaler ◽

George Georgoussis ◽

...

Keyword(s):

Polarized Light ◽

Backscatter Coefficient ◽

Lidar System ◽

Circularly Polarized Light ◽

Circularly Polarized ◽

Polarized Emission ◽

Linearly Polarized ◽

Reference Measurements ◽

Backscattered Signals ◽

Aerosol Types

<p>The EVE (Enhancement and Validation of ESA products) lidar is a mobile, ground-based, polarization lidar system, developed to provide ground reference measurements for the validation of the Aeolus L2A products. The system utilizes a dual-laser/dual-telescope configuration that emits linearly and circularly polarized light at 355 nm&#160; interleaved and detects the linear and circular depolarization on the backscattered signals as well as the Raman backscattering at 387 nm. Consequently, the particle optical properties of backscatter coefficient, extinction coefficient, linear and circular depolarization ratios can be measured by the lidar. Moreover, the system&#8217;s dual configuration enables to mimic both the operation of ALADIN on board Aeolus that relies on the circularly polarized emission and the operation of a polarization lidar system with linearly polarized emission. Besides EVE&#8217;s main goal of the Aeolus L2A products performance evaluation under a wide variety of aerosol types, EVE can also validate the linear to circular depolarization conversions, which have to be used for the harmonization of the linearly polarized lidar systems with Aeolus, and as such, to evaluate any possible biases of the efforts of these systems on Aeolus L2A validation.</p>

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The Electrical Activity of Saharan Dust as perceived from Surface Electric Field Observations in Greece

10.5194/acp-2020-668 ◽

2020 ◽

Cited By ~ 1

Author(s):

Vasiliki Daskalopoulou ◽

Sotirios A. Mallios ◽

Zbigniew Ulanowski ◽

George Hloupis ◽

Anna Gialitaki ◽

...

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Field Enhancement ◽

Electric Circuit ◽

Saharan Dust ◽

Backscatter Coefficient ◽

Lidar System ◽

Realistic Description ◽

Atmospheric Conductivity

Abstract. We report on the electric field variations during Saharan dust advection over two atmospheric remote stations in Greece, using synergistic observations of the vertical atmospheric electric field strength (Ez) at ground and the lidar-derived particle backscatter coefficient profiles. Both parameters were monitored for the first time with the simultaneous deployment of a ground-based field mill electrometer and a multiwavelength lidar system. The field mill timeseries are processed to extract the diurnal variations of the Global Electric Circuit and remove fast field perturbations due to peak lightning activity. In order to identify the influence of the elevated dust layers on the ground Ez, we extract a Localized Reference Electric Field from the timeseries that reflects the local fair weather activity. Then, we compare it with the reconstructed daily average behaviour of the electric field and the Saharan dust layers' evolution, as depicted by the lidar system. Reported cases of enhanced vertical electric field for detached pure dust layers suggest the presence of in-layer electric charges. Although higher dust loads are expected to result in electric field enhancement, episodic cases that reduce the electric field are also observed. To quantitatively approach our results, we examine the dependency of Ez against theoretical assumptions for the distribution of separated charges within the electrified dust layer. Electrically neutral dust is approximated by atmospheric conductivity reduction, while charge separation areas within electrically active dust layers are approximated as finite extent cylinders. This physical approximation constitutes a more realistic description of the distribution of charges, as opposed to infinite extent geometries, and allows for analytical solutions of the electric field strength, so that observed electric field variations during the monitored dust outbreaks can be explained.

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Demonstration of an off-axis parabolic receiver for near-range retrieval of lidar ozone profiles

Atmospheric Measurement Techniques ◽

10.5194/amt-12-363-2019 ◽

2019 ◽

Vol 12 (1) ◽

pp. 363-370 ◽

Cited By ~ 4

Author(s):

Betsy M. Farris ◽

Guillaume P. Gronoff ◽

William Carrion ◽

Travis Knepp ◽

Margaret Pippin ◽

...

Keyword(s):

Surface Ozone ◽

Small Diameter ◽

Atmospheric Conditions ◽

Lidar System ◽

Near Surface ◽

Multiple Wavelengths ◽

High Bias ◽

Measurement Channels ◽

Transition Study

Abstract. During the 2017 Ozone Water Land Environmental Transition Study (OWLETS), the Langley mobile ozone lidar system utilized a new small diameter receiver to improve the retrieval of near-surface signals from 0.1 to 1 km in altitude. This new receiver utilizes a single 90 ∘ fiber-coupled, off-axis parabolic mirror resulting in a compact form that is easy to align. The single reflective surface offers the opportunity to easily expand its use to multiple wavelengths for additional measurement channels such as visible wavelength aerosol measurements. Detailed results compare the performance of the receiver to both ozonesonde and in situ measurements from a UAV platform, validating the performance of the near-surface ozone retrievals. Absolute O3 differences averaged 7 % between lidar and ozonesonde data from 0.1 to 1.0 km and yielded a 2.3 % high bias in the lidar data, well within the uncertainty of the sonde measurements. Conversely, lidar O3 measurements from 0.1 to 0.2 km averaged 10.5 % lower than coincident UAV O3. A more detailed study under more stable atmospheric conditions would be necessary to resolve the residual instrument differences reported in this work. Nevertheless, this unique added capability is a significant improvement allowing for near-surface observation of ozone.

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Calculation of the Overlap Function and Associated Error of an Elastic Lidar or a Ceilometer: Cross-Comparison with a Cooperative Overlap-Corrected System

Sensors ◽

10.3390/s20216312 ◽

2020 ◽

Vol 20 (21) ◽

pp. 6312

Author(s):

Michaël Sicard ◽

Alejandro Rodríguez-Gómez ◽

Adolfo Comerón ◽

Constantino Muñoz-Porcar

Keyword(s):

Temporal Variability ◽

Backscatter Coefficient ◽

Lidar System ◽

Mathematical Relationships ◽

The Relationship

This paper establishes the relationship between the signal of a lidar system corrected for the incomplete overlap effect and the signal of another lidar system or a ceilometer for which the overlap function is unknown. Simple mathematical relationships permit the estimation of the overlap function of the second system as well as the associated error. Several overlap functions have been retrieved with this method over a period of 1.5 years with two lidar systems of the Universitat Politècnica de Catalunya, Barcelona, Spain. The error when the overlap function reaches 1 is usually less than 7%. The temporal variability estimated over a period of 1.5 years is less than 11% in the first 1.5 km from the surface and peaks at 18% at heights between 1.7 and 2.4 km. The use of a non-appropriate overlap function in the retrieval of the backscatter coefficient yield errors up to 60% in the first 0.5 km and up to 20% above.

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The Determination of Aerosol Distribution by a No-Blind-Zone Scanning Lidar

Remote Sensing ◽

10.3390/rs12040626 ◽

2020 ◽

Vol 12 (4) ◽

pp. 626 ◽

Cited By ~ 1

Author(s):

Jie Wang ◽

Wenqing Liu ◽

Cheng Liu ◽

Tianshu Zhang ◽

Jianguo Liu ◽

...

Keyword(s):

Mass Movement ◽

Ground Level ◽

Pollution Sources ◽

Lower Atmosphere ◽

In Situ Observation ◽

Atmospheric Conditions ◽

Lidar System ◽

Blind Zone ◽

Aerosol Distribution ◽

Receiver System

A homemade portable no-blind zone laser detection and ranging (lidar) system was designed to map the three-dimensional (3D) distribution of aerosols based on a dual-field-of-view (FOV) receiver system. This innovative lidar prototype has a space resolution of 7.5 m and a time resolution of 30 s. A blind zone of zero meters, and a transition zone of approximately 60 m were realized with careful optical alignments, and were rather meaningful to the lower atmosphere observation. With a scanning platform, the lidar system was used to locate the industrial pollution sources at ground level. The primary parameters of the transmitter, receivers, and detectors are described in this paper. Acquiring a whole return signal of this lidar system represents the key step to the retrieval of aerosol distribution with applying a linear joining method to the two FOV signals. The vertical profiles of aerosols were retrieved by the traditional Fernald method and verified by real-time observations. To effectively and reliably retrieve the horizontal distributions of aerosols, a composition of the Fernald method and the slope method were applied. In this way, a priori assumptions of even atmospheric conditions and the already-known reference point in the lidar equation were avoided. No-blind-zone vertical in-situ observation of aerosol illustrated a detailed evolution from almost 0 m to higher altitudes. No-blind-zone detection provided tiny structures of pollution distribution in lower atmosphere, which is closely related to human health. Horizontal field scanning experiments were also conducted in the Shandong Province. The results showed a high accuracy of aerosol mass movement by this lidar system. An effective quantitative way to locate pollution sources distribution was paved with the portable lidar system after validation by the mass concentration of suspended particulate matter from a ground air quality station.

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Earlinet validation of CATS L2 product

EPJ Web of Conferences ◽

10.1051/epjconf/201817602005 ◽

2018 ◽

Vol 176 ◽

pp. 02005

Author(s):

Emmanouil Proestakis ◽

Vassilis Amiridis ◽

Michael Kottas ◽

Eleni Marinou ◽

Ioannis Binietoglou ◽

...

Keyword(s):

International Space Station ◽

Transport System ◽

Space Station ◽

Backscatter Coefficient ◽

Aerosol Transport ◽

Lidar System ◽

International Space

The Cloud-Aerosol Transport System (CATS) onboard the International Space Station (ISS), is a lidar system providing vertically resolved aerosol and cloud profiles since February 2015. In this study, the CATS aerosol product is validated against the aerosol profiles provided by the European Aerosol Research Lidar Network (EARLINET). This validation activity is based on collocated CATS-EARLINET measurements and the comparison of the particle backscatter coefficient at 1064nm.

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Towards continuous monitoring of aerosol hygroscopicity by Raman lidar measurements at the EARLINET station of Payerne

10.5194/acp-2019-289 ◽

2019 ◽

Author(s):

Francisco Navas Guzmán ◽

Giovanni Martucci ◽

Martine Collaud Coen ◽

María José Granados Muñoz ◽

Maxime Hervo ◽

...

Keyword(s):

Continuous Monitoring ◽

Raman Lidar ◽

Backscatter Coefficient ◽

Lidar System ◽

Remote Sensing Technique ◽

Accuracy And Precision ◽

Lidar Measurements ◽

Constant Altitude ◽

Aerosol Backscatter ◽

Aerosol Hygroscopicity

Abstract. This study focuses on the analysis of aerosol hygroscopicity using remote sensing technique. Continuous observations of aerosol backscatter coefficient, temperature and water vapour mixing ratio are performed by means of a Raman lidar system at the aerological station of MeteoSwiss at Payerne (Switzerland) since 2008. These measurements allow us to monitor in a continuous way any change of aerosol properties as a function of the relative humidity (RH). These changes can be observed either in time at constant altitude or in altitude at a constant time. The accuracy and precision of RH measurements from the lidar have been evaluated using the radiosonde (RS) technique as reference. A total of 172 RSs were used in this intercomparison which revealed a small bias (

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Inter-comparison of lidar and ceilometer retrievals for aerosol and Planetary Boundary Layer profiling over Athens, Greece

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-73-2011 ◽

2011 ◽

Vol 4 (1) ◽

pp. 73-99 ◽

Cited By ~ 4

Author(s):

G. Tsaknakis ◽

A. Papayannis ◽

P. Kokkalis ◽

V. Amiridis ◽

H. D. Kambezidis ◽

...

Keyword(s):

Boundary Layer ◽

Planetary Boundary Layer ◽

Layer Structure ◽

Saharan Dust ◽

Radiosonde Data ◽

Backscatter Coefficient ◽

Lidar System ◽

Height Range ◽

Tropospheric Aerosol ◽

Filter Radiometer

Abstract. This study presents an inter-comparison of two active remote sensors (lidar and ceilometer) in determining the structure of the Planetary Boundary Layer (PBL) and in retrieving tropospheric aerosol vertical profiles over Athens, Greece. This inter-comparison was performed under various strongly different aerosol concentrations (urban air pollution, biomass burning and Saharan dust event), implementing two different lidar systems (one portable Raymetrics S.A. lidar system running at 355 nm and one multi-wavelength Raman lidar system running at 355 nm, 532 nm and 1064 nm) and one CL31 Vaisala S.A. ceilometer (running at 910 nm). To convert the ceilometer data to data having the same wavelengths as those from the lidar, the backscatter-related Ångström exponent was estimated using ultraviolet multi-filter radiometer (UV-MFR) data. The inter-comparison was based on two parameters: the mixing layer structure and height determined by the presence of the suspended aerosols and the aerosol backscatter coefficient. Additionally, radiosonde data were used to derive the PBL height. In general a good agreement is found between the ceilometer and the lidar techniques in both inter-compared parameters in the height range from 500 m to 5000 m, while the limitations of each instrument are also examined.

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Dry versus wet marine particle optical properties: RH dependence of depolarization ratio, backscatter, and extinction from multiwavelength lidar measurements during SALTRACE

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-14199-2017 ◽

2017 ◽

Vol 17 (23) ◽

pp. 14199-14217 ◽

Cited By ~ 35

Author(s):

Moritz Haarig ◽

Albert Ansmann ◽

Josef Gasteiger ◽

Konrad Kandler ◽

Dietrich Althausen ◽

...

Keyword(s):

Sea Salt ◽

Strong Increase ◽

Aerosol Layer ◽

Marine Aerosol ◽

Depolarization Ratio ◽

Atmospheric Conditions ◽

Hygroscopic Growth ◽

Backscatter Coefficient ◽

Linear Depolarization Ratio ◽

Lidar Observations

Abstract. Triple-wavelength lidar observations of the depolarization ratio and the backscatter coefficient of marine aerosol as a function of relative humidity (RH) are presented with a 5 min time resolution. The measurements were performed at Barbados (13° N, 59° W) during the Saharan Aerosol Long-range Transport and Aerosol-Cloud interaction Experiment (SALTRACE) winter campaign in February 2014. The phase transition from spherical sea salt particles to cubic-like sea salt crystals was observed with a polarization lidar. The radiosonde and water-vapor Raman lidar observations show a drop in RH below 50 % in the marine aerosol layer simultaneously with a strong increase in particle linear depolarization ratio, which reaches values up to 0.12 ± 0.08 (at 355 nm), 0.15 ± 0.03 (at 532 nm), and 0.10 ± 0.01 (at 1064 nm). The lidar ratio (extinction-to-backscatter ratio) increased from 19 and 23 sr for spherical sea salt particles to 27 and 25 sr (at 355 and 532 nm, respectively) for cubic-like particle ensembles. Furthermore the scattering enhancement due to hygroscopic growth of the marine aerosol particles under atmospheric conditions was measured. Extinction enhancement factors from 40 to 80 % RH of 1.94 ± 0.94 at 355 nm, 3.70 ± 1.14 at 532 nm, and 5.37 ± 1.66 at 1064 nm were found. The enhanced depolarization ratios and lidar ratios were compared to modeling studies of cubic sea salt particles.

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