Polarized light scattering by inhomogeneous hexagonal monocrystals: Validation with ADEOS‐POLDER measurements

C.‐Labonnote, Laurent; Brogniez, Gérard; Buriez, J. C.; Doutriaux-Boucher, Marie; Gayet, Jean-François; Macke, Andreas

doi:10.1029/2000jd900642

Cited by 105 publications

(94 citation statements)

References 34 publications

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“…A description of the polarized reflection is given in Labonnote et al (2001) but a very brief description is given here. The polarized radiance depends on the Q, U, and V parameters of the Stokes vector given in Equation (1), and the polarized radiance is normalized by the ratio of pi-to-incident solar flux density.…”

Section: Testing the Ensemble Model's Prediction Of Total Reflection mentioning

confidence: 99%

“…The latitudinal distribution of the POLDER pixels and the scattering angle range used in this paper are shown in Table VII. The methodology used to test the ensemble model has been previously described in Labonnote et al (2001) and the radiative-transfer model used in this section is described in Doutriaux-Boucher et al (2000). However, a brief description of the methodology is given here.…”

Section: Testing the Ensemble Model's Prediction Of Total Reflection mentioning

confidence: 99%

“…The randomization of ice crystals in order to remove optical features may take a variety of forms such as distorting (described in section 3) or roughening the ice crystal mantles as described in Macke et al (1996a) and Yang and Liou (1998), respectively. Adding air and/or aerosol inclusions within the ice crystal (Macke et al, 1996b;Yang and Liou, 1998;Labonnote et al, 2001;Shcherbakov et al, 2006) will also diminish or remove optical features. It is not currently known which randomization process or combination of processes dominates in the deformation of ice crystals, though CPI images such as those presented in Baran (2007) do show that ice crystals are deformed and some form of inclusions is present.…”

Section: Introductionmentioning

confidence: 99%

“…It has been previously demonstrated that the best phase function to apply to the remote sensing of cirrus is one that is generally featureless and flat at backscattering angles (Foot, 1988;Baran et al, 1999;Francis et al, 1999;Knap et al, 1999;Doutriaux-Boucher et al, 2000;Baran et al, 2001;Labonnote et al, 2001;Baran et al, 2003;Field et al, 2003a;Jourdan et al, 2003;Ulanowski et al, 2003;Baran and Francis, 2004;Baran et al, 2005;Knap et al, 2005;Baran and Labonnote, 2006;Shcherbakov et al, 2006;Ulanowski et al, 2006). In order to theoretically generate featureless phase functions (i.e.…”

Section: Introductionmentioning

confidence: 99%

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A self‐consistent scattering model for cirrus. I: The solar region

Baran

C.‐Labonnote²

2007

Quart J Royal Meteoro Soc

129

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ABSTRACT:In this paper a self-consistent scattering model for cirrus is presented. The model consists of an ensemble of ice crystals where the smallest ice crystal is represented by a single hexagonal ice column. As the overall ice crystal size increases, the ice crystals become progressively more complex by arbitrarily attaching other hexagonal elements until a chain-like ice crystal is formed, this representing the largest ice crystal in the ensemble. The ensemble consists of six ice crystal members whose aspect ratios (ratios of the major-to-minor axes of the circumscribed ellipse) are allowed to vary between unity and 1.84 for the smallest and largest ice crystal, respectively. The ensemble model's prediction of parameters fundamental to solar radiative transfer through cirrus such as ice water content and the volume extinction coefficient is tested using in situ based data obtained from the midlatitudes and Tropics. It is found that the ensemble model is able to generally predict the ice water content and extinction measurements within a factor of two. Moreover, the ensemble model's prediction of cirrus spherical albedo and polarized reflection are tested against a space-based instrument using one day of global measurements. The space-based instrument is able to sample the scattering phase function between the scattering angles of approximately 60°and 180°, and a total of 37 581 satellite pixels were used in the present analysis covering latitude bands between 43.75°S and 76.58°N. It is found that the ensemble model phase function is well able to minimize significantly differences between satellite-based measurements of spherical albedo and the ensemble model's prediction of spherical albedo. The satellite-based measurements of polarized reflection are found to be reasonably described by more simple members of the ensemble. The ensemble model presented in this paper should find wide applicability to the remote sensing of cirrus as well as more fundamental solar radiative transfer calculations through cirrus, and improved solar optical properties for climate and Numerical Weather Prediction models.

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Section: Testing the Ensemble Model's Prediction Of Total Reflection mentioning

confidence: 99%

Section: Testing the Ensemble Model's Prediction Of Total Reflection mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A self‐consistent scattering model for cirrus. I: The solar region

Baran

C.‐Labonnote²

2007

Quart J Royal Meteoro Soc

129

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“…The studies indicate that ice crystals occur with geometries with various degrees of complexity, e.g., pristine hexagonal columns, plates, and bullets, rosettes of different forms, and complicated and irregular aggregates. Furthermore, some detailed structures, such as surface roughness, hollow structure, and inhomogeneity (with air bubbles or ice nuclei inside), have been widely noted in the observations and considered for numerical studies (Ulanowski et al, 2012(Ulanowski et al, , 2014Schmitt and Heymsfield, 2007;Labonnote et al, 2001). Both the ice particle overall geometry and detailed structure have a significant effect on the optical properties.…”

Section: Introductionmentioning

confidence: 99%

A two-habit model for the microphysical and optical properties of ice clouds

et al. 2014

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Abstract. To provide a better representation of natural ice clouds, a novel ice cloud model is developed by assuming an ice cloud to consist of an ensemble of hexagonal columns and 20-element aggregates with specific habit fractions at each particle size bin. The microphysical and optical properties of this two-habit model (THM) are compared with both laboratory and in situ measurements, and its performance in downstream satellite remote sensing applications is assessed. The ice water contents and median mass diameters calculated based on the THM closely agree with in situ measurements made during 11 field campaigns. In this study, the scattering, absorption, and polarization properties of ice crystals are calculated with a combination of the invariant imbedding T matrix, pseudo-spectral time domain, and improved geometricoptics methods over an entire practical range of particle sizes. The phase functions, calculated based on the THM, show close agreement with counterparts from laboratory and in situ measurements and from satellite-based retrievals. When the THM is applied to the retrievals of cloud microphysical and optical properties from MODIS (the Moderate Resolution Imaging Spectroradiometer) observations, excellent spectral consistency is achieved; specifically, the retrieved cloud optical thicknesses based on the visible/near infrared bands and the thermal infrared bands agree quite well. Furthermore, a comparison between the polarized reflectivities observed by the PARASOL satellite and from theoretical simulations illustrates that the THM can be used to represent ice cloud polarization properties.

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Effects of spherical inclusions on scattering properties of small ice cloud particles

Hong

Minnis

2015

JGR Atmospheres

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The single-scattering properties of small ice crystals containing four types of spherical inclusions, ammonium sulfate (NH 4 ) 2 SO 4 , ammonium nitrate NH 3 NO 3 , air bubbles, and soot, are investigated at 0.65 and 2.13 μm. Small, randomly oriented hexagonal ice columns with spherical inclusions that are randomly distributed with standard gamma size distributions in the columns are considered in the present study. Ice crystals with inclusions of (NH 4 ) 2 SO 4 and NH 3 NO 3 essentially have the same features due to their similar refractive indices. Nonzero scattering matrix elements are sensitive to inclusion type and amount, and show differences between 0.65 and 2.13 μm. The extinction efficiency Q e of small ice crystals at 0.65 μm is near 2.0 and essentially unaffected by variations in inclusion volume, in contrast to strong influences of inclusion amount on Q e at 2.13 μm. The single-scattering albedo ϖ 0 of ice crystals, nearly equal to 1.0, is not affected by inclusions of (NH 4 ) 2 SO 4 , NH 3 NO 3 , and air bubbles. Soot inclusions strongly affect ϖ 0 , which decreases to about 0.5 with increasing soot amounts. The asymmetry factor g is substantially affected by (NH 4 ) 2 SO 4 , NH 3 NO 3 , and soot and the variations in their amounts. Full Stokes parameters of cirrus clouds consisting of uniform hexagonal ice columns with inclusions are computed using a polarized radiative transfer model. Sensitivities of light intensity and polarization of cirrus clouds to types and amounts of inclusions and cirrus cloud optical thicknesses are found to depend on wavelength. The present results suggest that different types of inclusions for small ice crystals should be considered when developing realistic ice crystal optical properties, and that light intensity and polarization of cirrus clouds and their angular distribution features, in the absence of other effects such as cavities and surface roughness, imply the potential for identifying pure ice crystals from those with aerosol inclusions.

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Polarized light scattering by inhomogeneous hexagonal monocrystals: Validation with ADEOS‐POLDER measurements

Cited by 105 publications

References 34 publications

A self‐consistent scattering model for cirrus. I: The solar region

A self‐consistent scattering model for cirrus. I: The solar region

A two-habit model for the microphysical and optical properties of ice clouds

Effects of spherical inclusions on scattering properties of small ice cloud particles

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