High spectral resolution lidar to measure optical scattering properties of atmospheric aerosols 1: Theory and instrumentation

Shipley, S. T.; Tracy, D. H.; Eloranta, E. W.; Trauger, John T.; Sroga, J. T.; Roesler, F. L.; Weinman, J. A.

doi:10.1364/ao.22.003716

Cited by 283 publications

(145 citation statements)

References 18 publications

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“…Advanced lidar systems like Raman lidar systems (Ansmann et al, 1990(Ansmann et al, , 1992 or high spectral resolution lidar (HSRL) systems (Shipley et al, 1983;Shimizu et al, 1983;Piironen and Eloranta, 1994) with polarization sensitive channels (Sassen et al, 1989;Freudenthaler et al, 2009) provide information about the optical properties of aerosol layers. Spaceborne lidar measurements are an excellent tool to examine the global vertical distribution of aerosols.…”

Section: Introductionmentioning

confidence: 99%

Optical properties of long-range transported Saharan dust over Barbados as measured by dual-wavelength depolarization Raman lidar measurements

et al. 2015

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Abstract. Dual-wavelength Raman and depolarization lidar observations were performed during the Saharan Aerosol Long-range Transport and Aerosol-Cloud interaction Experiment in Barbados in June and July 2013 to characterize the optical properties and vertical distribution of long-range transported Saharan dust after transport across the Atlantic Ocean. Four major dust events were studied during the measurements from 15 June to 13 July 2013 with aerosol optical depths at 532 nm of up to 0.6. The vertical aerosol distribution was characterized by a three-layer structure consisting of the boundary layer, the entrainment or mixing layer and the pure Saharan dust layer. The upper boundary of the pure dust layer reached up to 4.5 km in height. The contribution of the pure dust layer was about half of the total aerosol optical depth at 532 nm. The total dust contribution was about 50-70 % of the total aerosol optical depth at 532 nm. The lidar ratio within the pure dust layer was found to be wavelength independent with mean values of 53 ± 5 sr at 355 nm and 56 ± 7 sr at 532 nm. For the particle linear depolarization ratio, wavelength-independent mean values of 0.26 ± 0.03 at 355 nm and 0.27 ± 0.01 at 532 nm have been found.

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Section: Introductionmentioning

confidence: 99%

Optical properties of long-range transported Saharan dust over Barbados as measured by dual-wavelength depolarization Raman lidar measurements

et al. 2015

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“…The most basic systems use only information about the elastic lidar signal to derive backscatter coefficient by aerosol particles but require an assumption about the extinction-to-backscatter ratio (lidar ratio, LR) (Fernald et al, 1972;Klett, 1981Klett, , 1985Fernald, 1984). More advanced systems such as Raman (Ansmann et al, 1992;Whiteman et al, 1992) and HSRL (High Spectral Resolution Lidar) (Shipley et al, 1983;Grund and Eloranta, 1991) are able to provide independent measurements of backscatter and extinction coefficients (β and α, respectively) without LR assumption. Also, the depolarization measurements are a lidar improvement that provide information about the shape of aerosols and allow us to characterize the aerosol type (Murayama et al, 2004;Miffre et al, 2011;Bravo-Aranda et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Comparative assessment of GRASP algorithm for a dust event over Granada (Spain) during ChArMEx-ADRIMED 2013 campaign

et al. 2017

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Abstract. In this study, vertical profiles and columnintegrated aerosol properties retrieved by the GRASP (Generalized Retrieval of Atmosphere and Surface Properties) algorithm are evaluated with in situ airborne measurements made during the ChArMEx-ADRIMED field campaign in summer 2013. In the framework of this campaign, two different flights took place over Granada (Spain) during a desert dust episode on 16 and 17 June. The GRASP algorithm, which combines lidar and sun-sky photometer data measured at Granada, was used to retrieve aerosol properties. Two sun-photometer datasets are used: one co-located with the lidar system and the other in the Cerro Poyos station, approximately 1200 m higher than the lidar system but at a short horizontal distance.Column-integrated aerosol microphysical properties retrieved by GRASP are compared with AERONET products showing a good agreement. Differences between GRASP retrievals and airborne extinction profiles are in the range of 15 to 30 %, depending on the instrument on board the aircraft used as reference. On 16 June, a case where the dust layer was coupled to the aerosol layer close to surface, the total volume concentration differences between in situ data and GRASP retrieval are 15 and 36 % for Granada and Cerro Poyos retrievals, respectively. In contrast, on 17 June the dust layer was decoupled from the aerosol layer close to the surface, and the differences are around 17 % for both retrievals. In general, all the discrepancies found are within the uncertainly limits, showing the robustness and reliability of the GRASP algorithm. However, the better agreement found for the Cerro Poyos retrieval with the aircraft data and the vertical homogeneity of certain properties retrieved with GRASP, such as the scattering Ångström exponent, for cases with aerosol layers characterized by different aerosol types, shows that uncertainties in the vertical distribution of the aerosol properties have to be considered.The comparison presented here between GRASP and other algorithms (i.e. AERONET and LIRIC) and with airborne in situ measurements shows the potential to retrieve the optical and microphysical profiles of the atmospheric aerosol properties. Also, the advantage of GRASP versus LIRIC is that GRASP does not assume the results of the AERONET inversion as a starting point.

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“…Lidar techniques based on the vibrational and rotational Raman effect, like RRL (rotational Raman lidar) allow for the measurement of trace gas profiles (Whiteman et al, 1992;Turner et al, 2002;Wulfmeyer et al, 2010;Haarig et al, 2016) as well as profiles of atmospheric temperature, particle backscatter cross section, particle extinction cross section, and particle depolarization properties (Behrendt et al, 2002;Hammann et al, 2015;Radlach et al, 2008). High-spectral-resolution lidar (HSRL) systems furthermore allow for cloud and particle characterization (Shipley et al, 1983). Multi-wavelength lidar systems offer the potential to retrieve the optical, microphysical, and chemical properties of aerosols (Mamouri et al, 2012), but these systems are rare and the inversion algorithms are very complex.…”

Section: Introductionmentioning

confidence: 99%

Development and application of a backscatter lidar forward operator for quantitative validation of aerosol dispersion models and future data assimilation

et al. 2017

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Abstract.A new backscatter lidar forward operator was developed which is based on the distinct calculation of the aerosols' backscatter and extinction properties. The forward operator was adapted to the COSMO-ART ash dispersion simulation of the Eyjafjallajökull eruption in 2010. While the particle number concentration was provided as a model output variable, the scattering properties of each individual particle type were determined by dedicated scattering calculations. Sensitivity studies were performed to estimate the uncertainties related to the assumed particle properties. Scattering calculations for several types of non-spherical particles required the usage of T-matrix routines. Due to the distinct calculation of the backscatter and extinction properties of the models' volcanic ash size classes, the sensitivity studies could be made for each size class individually, which is not the case for forward models based on a fixed lidar ratio. Finally, the forward-modeled lidar profiles have been compared to automated ceilometer lidar (ACL) measurements both qualitatively and quantitatively while the attenuated backscatter coefficient was chosen as a suitable physical quantity. As the ACL measurements were not calibrated automatically, their calibration had to be performed using satellite lidar and ground-based Raman lidar measurements. A slight overestimation of the model-predicted volcanic ash number density was observed. Major requirements for future data assimilation of data from ACL have been identified, namely, the availability of calibrated lidar measurement data, a scattering database for atmospheric aerosols, a better representation and coverage of aerosols by the ash dispersion model, and more investigation in backscatter lidar forward operators which calculate the backscatter coefficient directly for each individual aerosol type. The introduced forward operator offers the flexibility to be adapted to a multitude of model systems and measurement setups.

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High spectral resolution lidar to measure optical scattering properties of atmospheric aerosols 1: Theory and instrumentation

Cited by 283 publications

References 18 publications

Optical properties of long-range transported Saharan dust over Barbados as measured by dual-wavelength depolarization Raman lidar measurements

Optical properties of long-range transported Saharan dust over Barbados as measured by dual-wavelength depolarization Raman lidar measurements

Comparative assessment of GRASP algorithm for a dust event over Granada (Spain) during ChArMEx-ADRIMED 2013 campaign

Development and application of a backscatter lidar forward operator for quantitative validation of aerosol dispersion models and future data assimilation

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