Sensitivity of retrieved POLDER directional cloud optical thickness to various ice particle models

Doutriaux-Boucher, Marie; Buriez, J. C.; Brogniez, Gérard; C.‐Labonnote, Laurent; Baran, Anthony J.

doi:10.1029/1999gl010870

Cited by 64 publications

(54 citation statements)

References 11 publications

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“…7b. Several previous studies have also noticed such a resemblance (e.g., Doutriaux-Boucher et al, 2000;C.-Labonnote et al, 2001;Knap et al, 2005;Baran and Labonnote, 2006). However, the reason behind this resemblance still remains unexplained.…”

Section: Potential Implications For the Derivation Of Seasonal Variatmentioning

confidence: 85%

“…The Baum05 model also provides a connection between ice particle optical properties with the measured environmental conditions, such as the temperature and humidity, which are the key variants in the ice cloud parameterization schemes for GCMs (Donner et al, 1997;Kristjánsson et al, 2000). A very attractive advantage of the IHM model has been demonstrated in many studies Doutriaux-Boucher et al, 2000;C.-Labonnote et al, 2001;Baran and Labonnote, 2006). These studies showed that based on the IHM model consistent ice cloud spherical albedos are retrieved from POLDER observations at different viewing directions, while use of a scattering phase function based on pristine and smooth ice hexagonal columns or plates such as those used in Baum05 model may lead to inconsistent retrievals.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…However, only recently has the influence of the pattern of P 11 on ice optical thickness retrieval been discussed (e.g., Doutriaux-Boucher et al, 2000;C.-Labonnote et al, 2001;Knap et al, 2005;Baran and Labonnote, 2006). These studies indicate that optical thickness retrievals that are based on different ice scattering phase functions can differ substantially.…”

Section: Potential Implications For the Derivation Of Seasonal Variatmentioning

confidence: 96%

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Influence of ice particle model on satellite ice cloud retrieval: lessons learned from MODIS and POLDER cloud product comparison

et al. 2009

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Abstract. The influence is investigated of the assumed ice particle microphysical and optical model on inferring ice cloud optical thickness (τ ) from satellite measurements of the Earth's reflected shortwave radiance. Ice cloud τ are inferred, and subsequently compared, using products from MODIS (MODerate resolution Imaging Spectroradiometer) and POLDER (POLarization and Directionality of the Earth's Reflectances). POLDER τ values are found to be substantially smaller than those from collocated MODIS data. It is shown that this difference is caused primarily by the use of different ice particle bulk scattering models in the two retrievals, and more specifically, the scattering phase function. Furthermore, the influence of the ice particle model on the derivation of ice cloud radiative forcing (CRF) from satellite retrievals is studied. Three sets of shortwave CRF are calculated using different combinations of the retrieval and associated ice particle models. It is shown that the uncertainty associated with an ice particle model may lead to two types of errors in estimating CRF from satellite retrievals. One stems from the retrieval itself and the other is due to the optical properties, such as the asymmetry factor, used for CRF calculations. Although a comparison of the CRFs reveals that these two types of errors tend to cancel each other, significant differences are still found between the three CRFs, which indicates that the ice particle model affects notCorrespondence to: Z. Zhang (zzbatmos@umbc.edu) only optical thickness retrievals but also CRF calculations. In addition to CRF, the effect of the ice particle model on the derivation of seasonal variation of τ from satellite measurements is discussed. It is shown that optical thickness retrievals based on the same MODIS observations, but derived using different assumptions of the ice particle model, can be substantially different. These differences can be divided into two parts. The first-order difference is mainly caused by the differences in the asymmetry factor. The second-order difference is related to seasonal changes in the sampled scattering angles and therefore dependent on the sun-satellite viewing geometry. Because of this second-order difference, the use of different ice particle models may lead to a different understanding of the seasonal variation of τ .

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Section: Potential Implications For the Derivation Of Seasonal Variatmentioning

confidence: 85%

Section: Summary and Discussionmentioning

confidence: 99%

Section: Potential Implications For the Derivation Of Seasonal Variatmentioning

confidence: 96%

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Influence of ice particle model on satellite ice cloud retrieval: lessons learned from MODIS and POLDER cloud product comparison

et al. 2009

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“…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%

“…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%

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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A self‐consistent scattering model for cirrus. II: The high and low frequencies

Baran

Cotton

Furtado

et al. 2013

Quart J Royal Meteoro Soc

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This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.The predictive quality of an ensemble model of cirrus ice crystals to model passive and active measurements of ice cloud, from the ultraviolet (UV) to the microwave, is tested. The ensemble model predicts m ∝ D 2 , where D is the maximum dimension of the ice crystal, and m is its mass. This predicted m-D relationship is applied to a moment estimation parametrization of the particle size distribution (PSD), to estimate the PSD shape, given ice water content (IWC) and in-cloud temperature. The same microphysics is applied across the electromagnetic spectrum to model UV, infrared, microwave and radar observations. The short-wave measurements consist of airborne UV backscatter lidar (light detection and ranging) estimates of the volume extinction coefficient, total solar optical depth, and spacebased multi-directional spherical albedo retrievals, at 0.865 µm, between the scattering angles 85 • and 125 • . The airborne long-wave measurements consist of high-resolution interferometer upwelling brightness temperatures, obtained between the wavelengths of about 3.45 µm and 4.1 µm, and 8.0 µm to 12.0 µm. The low-frequency measurements consist of ground-based Chilbolton 35 GHz radar reflectivity measurements and spacebased upwelling 190 GHz brightness temperature measurements. The predictive quality of the ensemble model is demonstrated to be generally within the experimental uncertainty of the lidar backscatter estimates of the volume extinction coefficient and total solar optical depth. The ensemble model prediction of the high-resolution brightness temperature measurements is generally within ±2 K and ±1 K at solar and infrared wavelengths, respectively. The 35 GHz radar reflectivity and 190 GHz brightness temperatures are generally simulated to within ±2 dBZ e , and ±2 K, respectively. The directional spherical albedo observations suggest that the scattering phase function of the most randomized ensemble model gives the best fit to the measurements (generally within ±3%). This article demonstrates that the ensemble model, assuming the same microphysics, is physically consistent across the electromagnetic spectrum.

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Sensitivity of retrieved POLDER directional cloud optical thickness to various ice particle models

Cited by 64 publications

References 11 publications

Influence of ice particle model on satellite ice cloud retrieval: lessons learned from MODIS and POLDER cloud product comparison

Influence of ice particle model on satellite ice cloud retrieval: lessons learned from MODIS and POLDER cloud product comparison

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

A self‐consistent scattering model for cirrus. II: The high and low frequencies

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