Analysis of atmospheric lidar observations: some comments

Fernald, F. G.

doi:10.1364/ao.23.000652

Cited by 1,644 publications

(1,074 citation statements)

References 6 publications

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“…-elastic backscatter coefficient: profile of particle backscatter coefficient β that is derived from an elastic signal only (Klett, 1981;Fernald, 1984;Di Girolamo et al, 1999;Masci, 1999),…”

Section: Earlinet Lidar Data Analyzer (Elda)mentioning

confidence: 99%

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EARLINET Single Calculus Chain – technical – Part 2: Calculation of optical products

et al. 2016

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Abstract. In this paper we present the automated software tool ELDA (EARLINET Lidar Data Analyzer) for the retrieval of profiles of optical particle properties from lidar signals. This tool is one of the calculus modules of the EARLINET Single Calculus Chain (SCC) which allows for the analysis of the data of many different lidar systems of EARLINET in an automated, unsupervised way. ELDA delivers profiles of particle extinction coefficients from Raman signals as well as profiles of particle backscatter coefficients from combinations of Raman and elastic signals or from elastic signals only. Those analyses start from pre-processed signals which have already been corrected for background, range dependency and hardware specific effects. An expert group reviewed all algorithms and solutions for critical calculus subsystems which are used within EARLINET with respect to their applicability for automated retrievals. Those methods have been implemented in ELDA. Since the software was designed in a modular way, it is possible to add new or alternative methods in future. Most of the implemented algorithms are well known and well documented, but some methods have especially been developed for ELDA, e.g., automated vertical smoothing and temporal averaging or the handling of effective vertical resolution in the case of lidar ratio retrievals, or the merging of near-range and far-range products. The accuracy of the retrieved profiles was tested following the procedure of the EARLINET-ASOS algorithm inter-comparison exercise which is based on the analysis of synthetic signals. Mean deviations, mean relative deviations, and normalized root-mean-square deviations were calculated for all possible products and three height layers. In all cases, the deviations were clearly below the maximum allowed values according to the EARLINET quality requirements.

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Section: Earlinet Lidar Data Analyzer (Elda)mentioning

confidence: 99%

“…Those are the iterative method (Di Girolamo et al, 1999;Masci, 1999) and the Klett-Fernald algorithm in backward integration mode (Klett, 1981;Fernald, 1984) . Both methods are implemented in ELDA and the user has to choose among them.…”

Section: Elastic Backscatter Coefficientmentioning

confidence: 99%

EARLINET Single Calculus Chain – technical – Part 2: Calculation of optical products

et al. 2016

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“…To compensate for the attenuation incurred within and below the aerosol layers, the estimated aerosol backscattering coefficients β e were used to identify layers. The β e were computed with the forward method (Klett, 1981;Fernald, 1983;Young and Vaughan, 2009) by assuming a layer top at 8 km. Lidar ratios (S) were chosen as 25 (532 nm) and 40 (1064 nm) .…”

Section: T Luo Et Al: Lidar-based Remote Sensing Of Atmospheric Boumentioning

confidence: 99%

Lidar-based remote sensing of atmospheric boundary layer height over land and ocean

2014

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Abstract. Atmospheric boundary layer (ABL) processes are important in climate, weather and air quality. A better understanding of the structure and the behavior of the ABL is required for understanding and modeling of the chemistry and dynamics of the atmosphere on all scales. Based on the systematic variations of the ABL structures over different surfaces, different lidar-based methods were developed and evaluated to determine the boundary layer height and mixing layer height over land and ocean. With Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) micropulse lidar (MPL) and radiosonde measurements, diurnal and season cycles of atmospheric boundary layer depth and the ABL vertical structure over ocean and land are analyzed. The new methods are then applied to satellite lidar measurements. The aerosol-derived global marine boundary layer heights are evaluated with marine ABL stratiform cloud top heights and results show a good agreement between them.

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“…During the day, the well-known Klett-Fernald (Klett, 1985;Fernald, 1984) method is used to solve the equation for the elastic lidar return signal, where K(λ 0 ) includes all height-independent terms, O(z) is the overlap function, β = β p +β m is the total elastic backscatter coefficients and α = α p + α m is the total extinction coefficient. Assuming a height independent particle lidar ratio (L p = α p /β p ) and having chosen a reference height, z 0 , where the particle contribution is negligible, i.e., β m (z 0 ) β p (z 0 ), the solution can be conveniently written as:…”

Section: Aerosol Inversionsmentioning

confidence: 99%

“…This, however, is subject to noise fluctuations as the number of detected photons P (z 0 ) has a Poisson distribution with λ = √ P (z 0 ). In some algorithms discussed in the literature (Fernald, 1984), a small but non-zero value of β p (z 0 ) is chosen to compensate the fact that P (z 0 ) = P m (z 0 ) at the starting point of the integration. There are also algorithms where the reference height is chosen to minimize…”

Section: Aerosol Inversionsmentioning

confidence: 99%

A permanent Raman lidar station in the Amazon: description, characterization, and first results

Barbosa¹,

Barja²,

Pauliquevis

et al. 2014

Atmos. Meas. Tech.

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Abstract.A permanent UV Raman lidar station, designed to perform continuous measurements of aerosols and water vapor and aiming to study and monitor the atmosphere from weather to climatic time scales, became operational in the central Amazon in July 2011. The automated data acquisition and internet monitoring enabled extended hours of daily measurements when compared to a manually operated instrument. This paper gives a technical description of the system, presents its experimental characterization and the algorithms used for obtaining the aerosol optical properties and identifying the cloud layers. Data from one week of measurements during the dry season of 2011 were analyzed as a mean to assess the overall system capability and performance. Both Klett and Raman inversions were successfully applied. A comparison of the aerosol optical depth from the lidar and from a co-located Aerosol Robotic Network (AERONET) sun photometer showed a correlation coefficient of 0.86. By combining nighttime measurements of the aerosol lidar ratio (50-65 sr), back-trajectory calculations and fire spots observed from satellites, we showed that observed particles originated from biomass burning. Cirrus clouds were observed in 60 % of our measurements. Most of the time they were distributed into three layers between 11.5 and 13.4 km a.g.l. The systematic and long-term measurements being made by this new scientific facility have the potential to significantly improve our understanding of the climatic implications of the anthropogenic changes in aerosol concentrations over the pristine Amazonia.

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Analysis of atmospheric lidar observations: some comments

Cited by 1,644 publications

References 6 publications

EARLINET Single Calculus Chain – technical – Part 2: Calculation of optical products

EARLINET Single Calculus Chain – technical – Part 2: Calculation of optical products

Lidar-based remote sensing of atmospheric boundary layer height over land and ocean

A permanent Raman lidar station in the Amazon: description, characterization, and first results

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