Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements

Gouveia, D. A.; Barja, Boris; Barbosa, H. M.; Seifert, Patric; Baars, Holger; Pauliquevis, Theotônio; Artaxo, Paulo

doi:10.5194/acp-17-3619-2017

Cited by 47 publications

(55 citation statements)

References 76 publications

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“…These results are consistent with Platt and Dilley () where they found that the lidar ratio overall decreased with cloud temperature. Gouveia et al () and Seifert et al () also showed little dependence of observed lidar ratio on temperature. Chen et al () showed an increase of lidar ratio with increasing cloud temperature for a similar temperature range (~200 to 230 K) in which the lidar ratio increased from the present RL observations.…”

Section: Relationship Of Lidar Ratio and Temperaturementioning

confidence: 91%

Differences in Ice Cloud Optical Depth From CALIPSO and Ground‐Based Raman Lidar at the ARM SGP and TWP Sites

Balmes

Thorsen

2019

JGR Atmospheres

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Ice cloud column optical depths from the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite and ground‐based Raman lidars (RLs) at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) and Tropical Western Pacific (TWP) sites are compared for 8 and 4 years, respectively. The cloudy mean ice cloud column optical depths from CALIPSO Version 4 data product with a horizontal resolution of 5 km are 78% (63%) larger than those from the RLs with a resolution of 10 min/30 m at SGP (TWP) for collocated transparent profiles. The main difference at SGP is caused by the lidar ratio that for CALIPSO is related to its treatment of the multiple scattering factor. The main difference at TWP is caused by the averaging resolution. Large differences in the optical depth distribution between the CALIPSO and RL are found for small optical depths at both sites, which are due to optically very thin clouds only detectable by the RLs. The differences in ice cloud column optical depth distributions and their mean values between the CALIPSO and RL can largely be reconciled over both sites after accounting for the averaging resolutions, lidar ratios along with the CALIPSO multiple scattering factor treatment, sensitivity to optically very thin ice clouds, and definition of transparent profiles. This work also examines in detail the lidar ratios that are directly observed by the RLs, which does not support the temperature‐dependent parameterizations of ice cloud lidar ratio and multiple scattering factor used in CALIPSO's Version 4 data product.

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Section: Relationship Of Lidar Ratio and Temperaturementioning

confidence: 91%

Differences in Ice Cloud Optical Depth From CALIPSO and Ground‐Based Raman Lidar at the ARM SGP and TWP Sites

Balmes

Thorsen

2019

JGR Atmospheres

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“…This leads to a wrong attenuation correction and thus to wrong quasi-particle-backscatter coefficient and quasi-particle depolarization ratio values above the cloud base. Furthermore, multiple scattering at the large cloud hydrometeors leads to an additional underestimation of the light attenuation (see Seifert et al, 2007;Kienast-Sjögren et al, 2016, or Gouveia et al, 2017. For that reason, the current lidar stand-alone approach is trustworthy only at cloud bases and a few tens of metres above, depending on the cloud optical thickness.…”

Section: April 2013mentioning

confidence: 99%

Target categorization of aerosol and clouds by continuous multiwavelength-polarization lidar measurements

et al. 2017

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Abstract. Absolute calibrated signals at 532 and 1064 nm and the depolarization ratio from a multiwavelength lidar are used to categorize primary aerosol but also clouds in high temporal and spatial resolution. Automatically derived particle backscatter coefficient profiles in low temporal resolution (30 min) are applied to calibrate the lidar signals. From these calibrated lidar signals, new atmospheric parameters in temporally high resolution (quasi-particle-backscatter coefficients) are derived. By using thresholds obtained from multiyear, multisite EARLINET (European Aerosol Research Lidar Network) measurements, four aerosol classes (small; large, spherical; large, non-spherical; mixed, partly nonspherical) and several cloud classes (liquid, ice) are defined. Thus, particles are classified by their physical features (shape and size) instead of by source.The methodology is applied to 2 months of continuous observations (24 h a day, 7 days a week) with the multiwavelength-Raman-polarization lidar Polly XT during the High-Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP) 2 ) Observational Prototype Experiment (HOPE) in spring 2013. Cloudnet equipment was operated continuously directly next to the lidar and is used for comparison. By discussing three 24 h case studies, it is shown that the aerosol discrimination is very feasible and informative and gives a good complement to the Cloudnet target categorization. Performing the categorization for the 2-month data set of the entire HOPE campaign, almost 1 million pixel (5 min × 30 m) could be analysed with the newly developed tool. We find that the majority of the aerosol trapped in the planetary boundary layer (PBL) was composed of small particles as expected for a heavily populated and industrialized area. Large, spherical aerosol was observed mostly at the top of the PBL and close to the identified cloud bases, indicating the importance of hygroscopic growth of the particles at high relative humidity. Interestingly, it is found that on several days non-spherical particles were dispersed from the ground into the atmosphere.

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“…In this study, for accurately correcting the MS influence, we perform a full treatment of multiple scattering following the model of Hogan (2008). The model is also introduced and applied by Seifert et al (2007), Kienast-Sjögren et al (2016) and Gouveia et al (2017). In this model, the typically operated FOV of 1.3 mrad and the full divergence angle of 0.5 mrad in WACAL is input.…”

Section: Multiple Scattering Correctionmentioning

confidence: 99%

Optical and Geometrical Properties of Cirrus Clouds over the Tibetan Plateau Measured by Lidar and Radiosonde Sounding at the Summertime in 2014

Dai

Song

et al. 2017

Preprint

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Abstract. Optical and geometrical characteristics of cirrus clouds over Naqu (31.48°N,92.06°E), the Tibetan Plateau were determined from lidar and radiosonde measurements performed during the third TIbetan Plateau EXperiment of atmospheric sciences (TIPEX III) campaign from July to August 2014. For the analysis of the temperature dependence, the simultaneous observations by lidar and radiosonde were conducted. Cirrus clouds were generally observed ranging from 9.7 to 16.5 km above sea level (a.s.l.), with the cirrus middle temperatures in the range from −79.7 to −26.0 C  . The cloud thickness generally 15 differed from 0.12 to 2.55 km with a mean thickness of 1.22  0.70 km and 85.7% of the case studies had thickness smaller than 1.5 km. The retrievals of linear particle depolarization ratio, extinction coefficient and optical depth of cirrus clouds were performed. Moreover, the multiple scattering effect inside of cirrus cloud was corrected. The linear particle depolarization ratio of the cirrus clouds varied from 0.36 to 0.52, with a mean value of 0.44  0.037. The optical depth of all the cirrus clouds was between 0.01 and 3 following the scheme of Fernald-Klett method. Sub-visual, thin and opaque cirrus clouds were 20 observed at 9.52%, 57.14% and 33.34% of the measured cases, respectively. The temperature and thickness dependencies on optical properties were studied in detail. A maximum cirrus thickness of around 2 km was found at temperatures between −60 and −50 C  . This study shows that the cirrus mean extinction coefficient of the cirrus clouds increase with the increase of temperature. However, our measurements indicate that the linear particle depolarization ratio has the opposite change tendency along with temperature. The relationships between the presence of cirrus clouds and the temperature anomaly and deep 25Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2017-355 Manuscript under review for journal Atmos. Meas. Tech. Discussion started: 11 December 2017 c Author(s) 2017. CC BY 4.0 License. 2 convective activity are also discussed. The formation of cirrus clouds is also investigated and it has apparent relationship with the dynamic processes of Rossby wave and deep convective activity over the Tibetan Plateau. The cloud radiative forcing is calculated by Fu-Liou model and increases monotonously with the increase of optical depth.

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Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements

Cited by 47 publications

References 76 publications

Differences in Ice Cloud Optical Depth From CALIPSO and Ground‐Based Raman Lidar at the ARM SGP and TWP Sites

Differences in Ice Cloud Optical Depth From CALIPSO and Ground‐Based Raman Lidar at the ARM SGP and TWP Sites

Target categorization of aerosol and clouds by continuous multiwavelength-polarization lidar measurements

Optical and Geometrical Properties of Cirrus Clouds over the Tibetan Plateau Measured by Lidar and Radiosonde Sounding at the Summertime in 2014

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