Wind speed dependence of atmospheric boundary layer optical properties and ocean surface reflectance as observed by airborne backscatter lidar

Flamant, Cyrille; Trouillet, Vincent; Chazette, Patrick; Pelon, Jacques

doi:10.1029/98jc02284

Cited by 35 publications

(36 citation statements)

References 47 publications

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“…Below 1.75 km height a mixture of marine particles and dust particles prevailed so that the lidar ratio decreased. For pure marine conditions, the lidar ratio would be close to 15-25 sr (Flamant et al, 1998;Groß et al, 2011b;Burton et al, 2012;Dawson et al, 2015;Haarig et al, 2017). The SAL AOT was about 0.3 at 355 and 532 nm on this day.…”

Section: Case Study I: Comparison Of Polis and Bertha Observations (1mentioning

confidence: 99%

Triple-wavelength depolarization-ratio profiling of Saharan dust over Barbados during SALTRACE in 2013 and 2014

et al. 2017

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Abstract. Triple-wavelength polarization lidar measurements in Saharan dust layers were performed at Barbados (13.1 • N, 59.6 • W), 5000-8000 km west of the Saharan dust sources, in the framework of the Saharan Aerosol Longrange Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE-1, June-July 2013, SALTRACE-3, June-July 2014). Three case studies are discussed. High quality was achieved by comparing the dust linear depolarization ratio profiles measured at 355, 532, and 1064 nm with respective dual-wavelength (355, 532 nm) depolarization ratio profiles measured with a reference lidar. A unique case of long-range transported dust over more than 12 000 km is presented. Saharan dust plumes crossing Barbados were measured with an airborne triple-wavelength polarization lidar over Missouri in the midwestern United States 7 days later. Similar dust optical properties and depolarization features were observed over both sites indicating almost unchanged dust properties within this 1 week of travel from the Caribbean to the United States. The main results of the triple-wavelength polarization lidar observations in the Caribbean in the summer seasons of 2013 and 2014 are summarized. On average, the particle linear depolarization ratios for aged Saharan dust were found to be 0.252 ± 0.030 at 355 nm, 0.280 ± 0.020 at 532 nm, and 0.225 ± 0.022 at 1064 nm after approximately 1 week of transport over the tropical Atlantic. Based on published simulation studies we present an attempt to explain the spectral features of the depolarization ratio of irregularly shaped mineral dust particles, and conclude that most of the irregularly shaped coarse-mode dust particles (particles with diameters > 1 µm) have sizes around 1.5-2 µm. The SALTRACE results are also set into the context of the SAMUM-1 (Morocco, 2006) and SAMUM-2 (Cabo Verde, 2008) depolarization ratio studies. Again, only minor changes in the dust depolarization characteristics were observed on the way from the Saharan dust sources towards the Caribbean.

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Section: Case Study I: Comparison Of Polis and Bertha Observations (1mentioning

confidence: 99%

Triple-wavelength depolarization-ratio profiling of Saharan dust over Barbados during SALTRACE in 2013 and 2014

et al. 2017

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“…The nadir-pointing lidar is not sensitive to the wind direction related issues found in the sunglint measurements. Studying wind and slope variance relation using combined wind/lidar measurements can avoid uncertainty associated cloud/aerosol contaminaiton (Flamant et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Sea surface wind speed estimation from space-based lidar measurements

et al. 2008

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Abstract. Global satellite observations of lidar backscatter measurements acquired by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission and collocated sea surface wind speed data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E), are used to investigate the relation between wind driven wave slope variance and sea surface wind speed. The new slope variance -wind speed relation established from this study is similar to the linear relation from Cox-Munk (1954) and the log-linear relation from Wu (1990) for wind speed larger than 7 m/s and 13.3 m/s, respectively. For wind speed less than 7 m/s, the slope variance is proportional to the square root of the wind speed, assuming a two dimensional isotropic Gaussian wave slope distribution. This slope variance -wind speed relation becomes linear if a one dimensional Gaussian wave slope distribution and linear slope variance -wind speed relation are assumed. Contributions from whitecaps and subsurface backscattering are effectively removed by using 532 nm lidar depolarization measurements. This new slope variance -wind speed relation is used to derive sea surface wind speed from CALIPSO single shot lidar measurements (70 m spot size), after correcting for atmospheric attenuation. The CALIPSO wind speed result agrees with the collocated AMSR-E wind speed, with 1.2 m/s rms error. Ocean surface with lowest atmospheric loading and moderate wind speed (7-9 m/s) is used as target for lidar calibration correction.Correspondence to: Y. Hu (yongxiang.hu-1@nasa.gov)

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“…The polluted marine S a value of 51sr is significantly larger than that measured during the SEAS experiment [12], and other estimates of S a for marine aerosols ranging between 20-30 sr [13][14][15]. The biomass burning value of 58 sr is not at variance with the measurements of Voss et al To check for the consistency of the individual categories, we divided the measurements in each category into five optical depth classes and plotted the S a of each class within a category.…”

Section: Aerosol Types From Aeronetmentioning

confidence: 74%

Selection algorithm for the CALIPSO lidar aerosol extinction-to-backscatter ratio

2006

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The extinction-to-backscatter ratio (S a ) is an important parameter used in the determination of the aerosol extinction and subsequently the optical depth from lidar backscatter measurements. We outline the algorithm used to determine S a for the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) lidar. S a for the CALIPSO lidar will either be selected from a look-up table or calculated using the lidar measurements depending on the characteristics of aerosol layer. Whenever suitable lofted layers are encountered, S a is computed directly from the integrated backscatter and transmittance. In all other cases, the CALIPSO observables: the depolarization ratio, δ, the layer integrated attenuated backscatter, β', and the mean layer total attenuated color ratio, γ, together with the surface type, are used to aid in aerosol typing. Once the type is identified, a look-up-table developed primarily from worldwide observations, is used to determine the S a value. The CALIPSO aerosol models include desert dust, biomass burning, background, polluted continental, polluted dust, and marine aerosols.

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Wind speed dependence of atmospheric boundary layer optical properties and ocean surface reflectance as observed by airborne backscatter lidar

Abstract: Abstract.Airborne

Cited by 35 publications

References 47 publications

Triple-wavelength depolarization-ratio profiling of Saharan dust over Barbados during SALTRACE in 2013 and 2014

Triple-wavelength depolarization-ratio profiling of Saharan dust over Barbados during SALTRACE in 2013 and 2014

Sea surface wind speed estimation from space-based lidar measurements

Selection algorithm for the CALIPSO lidar aerosol extinction-to-backscatter ratio

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