Application of the Lidar to Air Pollution Measurements

Barrett, Earl W.; Bendov, O.

doi:10.1175/1520-0450(1967)006<0500:aotlta>2.0.co;2

Cited by 96 publications

(42 citation statements)

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“…Generally, the two unknowns of this equation, the backscatter and extinction coefficients, have to be related using either empirical or theoretical methods in order to be able to invert the lidar equation. There have been many discussions regarding the solutions of the lidar (e.g., Barrett and Ben-Dov, 1967;Viezee et al, 1969;Davis, 1969;Fernald, 1972;Platt, 1973Platt, , 1979Klett, 1981;Fernald, 1984;Flamant, 1996, andAnsmann et al, 1992). Forward solution of the backscatter coefficient was found to become rapidly unstable for optical depths greater than unity, unless the lidar ratio was specified with extreme accuracy (Platt, 1979).…”

Section: Methodsmentioning

confidence: 99%

“…The LAP lidar was successfully intercompared in the frame of the European Aerosol Research Lidar Network (EARLINET) systems, showing on the average an agreement of better than 5% for heights above 2 km in the backscatter coefficient Bockmann et al, 2004;Pappalardo et al, 2004). More technical and measurement details concerning the LAP lidar system can be found in the literature Amiridis et al, 2005 In this study, we present lidar measurements performed over Thessaloniki, for cases when cirrus clouds were observed in the period [2000][2001][2002][2003][2004][2005][2006].…”

Section: Instrumentationmentioning

confidence: 99%

“…Elastic backscatter and Raman lidars have been used to retrieve information on geometrical and optical properties of cirrus clouds, made through the application of methods that have been earlier demonstrated in the literature (e.g. Barrett and Ben-Dov, 1967;Viezee et al, 1969;Davis, 1969;Fernald et al , 1972;Platt, 1973;Platt, 1979;Klett, 1981;Fernald, 1984;Grund and Eloranta, 1990;Ansmann et al, 1992). Some key microphysical parameters are the extinction coefficient, lidar ratio and depolarization ratio as well as the mid-altitude and the corresponding mid-cloud temperature of cirrus clouds (Sunilkumar and Parameswaran, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…The evaluation of optical depth of cirrus clouds was done through the application of different methods which are already demonstrated in the literature. Most of these methods depend on the solution of the standard lidar equation (Barrett and Ben-Dov, 1967;Viezee et al, 1969;Davis, 1969;Fernald et al, 1972;Platt, 1973Platt, , 1979Klett, 1981;Fernald, 1984;Ansmann et al, 1992;Elouragini and Flamant, 1996;Wandinger, 1998). A different technique to determine the optical depth of cirrus clouds from elastic lidar signal has also been developed.…”

Section: Introductionmentioning

confidence: 99%

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Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station

Giannakaki¹,

Balis²,

Amiridis

et al. 2007

Atmos. Chem. Phys.

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Abstract. Optical and geometrical characteristics of cirrus clouds over Thessaloniki, Greece (40.6 • N, 22.9 • E) have been determined from the analysis of lidar and radiosonde measurements performed during the period from 2000 to 2006. Cirrus clouds are generally observed in a mid-altitude region ranging from 8.6 to 13 km, with mid-cloud temperatures in the range from −65 • to −38 • C. The cloud thickness generally ranges from 1 to 5 km and 38% of the cases studied have thickness between 2 and 3 km. The retrieval of optical depth and lidar ratio of cirrus clouds is performed using three different methods, taking into account multiple scattering effect. The mean optical depth is found to be 0.31±0.24 and the corresponding mean lidar ratio is 30±17 sr following the scheme of Klett-Fernald method. Sub-visual, thin and opaque cirrus clouds are observed at 3%, 57% and 40% of the measured cases, respectively. A comparison of the results obtained between the three methods shows good agreement. The multiple scattering errors of the measured effective extinction coefficients range from 20 to 60%, depending on cloud optical depth. The temperature and thickness dependencies on optical properties have also been studied in detail. A maximum mid-cloud depth of ∼3.5 km is found at temperatures around ∼−47.5 • C, while there is an indication that optical depth and mean extinction coefficient increases with increasing mid-cloud temperature. A correlation between optical depth and thickness was also found. However, no clear dependence of the lidar ratio values on the cloud temperature and thickness was found.

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Section: Methodsmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station

Giannakaki¹,

Balis²,

Amiridis

et al. 2007

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…Although a ratio quantity, Sa has units of steradian; the units will not be shown explicity in the discussions, tables and figures presented here. Solution techniques for solving the lidar equation to extract profiles of aerosol backscatter and/or extindtion from such lidar measurements generally assume some constraint for S, (e.g., Barrett and Ben-Dov, 1967;Fernald et al, 1972;Klett, 1981). The most common assumption is that S, is constant over a specified range interval.…”

Section: Introductionmentioning

confidence: 99%