Evaluation of cloud heterogeneity effects on total and polarized visible radiances as measured by POLDER/PARASOL and consequences for retrieved cloud properties

Cornet, Céline; Szczap, Frédéric; C.‐Labonnote, Laurent; Fauchez, Thomas; Parol, Frédéric; Thieuleux, F.; Riédi, J.; Dubuisson, Philippe; Ferlay, Nicolas

doi:10.1063/1.4804717

Cited by 6 publications

(4 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For practical and computational cost purposes, interpretation of such measurements generally also assumes 1-D radiative algorithm and PPH cloud. This assumption can be far from being realistic and leads to biases on the retrieved properties from passive sensors (Barker and Liu, 1995; Marshak, 2002Marshak, , 2007Lafont and Guillemet, 2004;Cornet et al, 2005Cornet et al, , 2013 and active sensors (Battaglia and Tanelli, 2011). These biases depend at least, on the cloud coverage and on the variability of cloud optical depth or water content.…”

Section: Introductionmentioning

confidence: 99%

“…Apart from the computational time, accurate 3-D cloudy radiative transfer problem is not an issue, per se (Evans and Wiscombe, 2004). Monte Carlo transfer models can indeed accurately and efficiently compute radiative properties for arbitrary cloud fields (Battaglia and Mantovani, 2005;Pincus and Evans, 2009;Mayer, 2009;Cornet et al, 2010Cornet et al, , 2013Battaglia and Tanelli, 2011;Fauchez et al, 2013). The difficulty is to generate cloud property fields that are statistically representative of cloud fields in nature.…”

Section: F Szczap Et Al: a Flexible Three-dimensional Cloud Generatmentioning

confidence: 99%

See 1 more Smart Citation

A flexible three-dimensional stratocumulus, cumulus and cirrus cloud generator (3DCLOUD) based on drastically simplified atmospheric equations and the Fourier transform framework

et al. 2014

Self Cite

View full text Add to dashboard Cite

Abstract. The 3DCLOUD algorithm for generating stochastic three-dimensional (3-D) cloud fields is described in this paper. The generated outputs are 3-D optical depth (τ ) for stratocumulus and cumulus fields and 3-D ice water content (IWC) for cirrus clouds. This model is designed to generate cloud fields that share some statistical properties observed in real clouds such as the inhomogeneity parameter ρ (standard deviation normalized by the mean of the studied quantity), the Fourier spectral slope β close to −5/3 between the smallest scale of the simulation to the outer L out (where the spectrum becomes flat). Firstly, 3DCLOUD assimilates meteorological profiles (humidity, pressure, temperature and wind velocity). The cloud coverage C, defined by the user, can also be assimilated, but only for stratocumulus and cumulus regime. 3DCLOUD solves drastically simplified basic atmospheric equations, in order to simulate 3-D cloud structures of liquid or ice water content. Secondly, the Fourier filtering method is used to constrain the intensity of ρ, β, L out and the mean of τ or IWC of these 3-D cloud structures. The 3DCLOUD model was developed to run on a personal computer under Matlab environment with the Matlab statistics toolbox. It is used to study 3-D interactions between cloudy atmosphere and radiation.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: F Szczap Et Al: a Flexible Three-dimensional Cloud Generatmentioning

confidence: 99%

A flexible three-dimensional stratocumulus, cumulus and cirrus cloud generator (3DCLOUD) based on drastically simplified atmospheric equations and the Fourier transform framework

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…Our method assumes that clouds are horizontally and vertically homogeneous owing to the use of plane-parallel radiative transfer algorithm (i.e., 1-D code). However, numerous studies have shown that the horizontal heterogeneity of clouds affects the scattered radiation measurements through three-dimensional radiative transfer effects (e.g., Marshak and Davis, 2005;Cornet et al, 2013;Zhang et al, 2012). The cloud heterogeneity may thus affect our estimation of aerosol and cloud properties as well as the DRE.…”

Section: Cloud Heterogeneity Effectsmentioning

confidence: 99%

Absorption of aerosols above clouds from POLDER/PARASOL measurements and estimation of their Direct Radiative Effect

Peers¹,

Waquet²,

Cornet³

et al. 2014

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. The albedo of clouds and the aerosol absorption are key parameters to evaluate the direct radiative effect of an aerosol layer above clouds. While most of the retrievals of above clouds aerosol characteristics rely on assumptions on the aerosol properties, this study offers a new method to evaluate aerosol and cloud optical properties simultaneously (i.e. aerosol and cloud optical thickness, aerosol single scattering albedo and angström exponent). It is based on multi-angle total and polarized radiances both provided by the A-train satellite instrument POLDER – Polarization and Directionality of Earth Reflectances. The sensitivities brought by each kind of measurements are used in a complementary way. Polarization mostly translates scattering processes and is thus used to estimate the scattering aerosol optical thickness and the aerosol size. On the other hand, total radiances, together with the scattering properties of aerosols, are used to evaluate the absorption optical thickness of aerosols and the cloud optical thickness. In addition, a procedure has been developed to process the shortwave direct radiative effect of aerosols above clouds based on exact modeling. Besides the three case studies (i.e. biomass burning aerosols from Africa and Siberia and Saharan dust), both algorithms have been applied on the South East Atlantic Ocean and results have been averaged through August 2006. The mean direct radiative effect is found to be 33.5 W m−2. Finally, the effect of the heterogeneity of clouds has been investigated and reveals that it affects mostly the retrieval of the cloud optical thickness and not much the aerosols properties. The homogenous cloud assumption used in both the properties retrieval and the DRE processing leads to a slight underestimation of the DRE.

show abstract

“…The scale invariant properties observed in real clouds can be controlled. The power spectra of the logarithm of their optical properties (optical depth, liquid water content or liquid water path for low clouds and ice water content for high clouds) typically exhibits a spectral slope of around −5/3 (Davis et al, 1994(Davis et al, , 1996(Davis et al, , 1997(Davis et al, , 1999Cahalan et al, 1994;Benassi et al, 2004;Hogan and Kew, 2005;Hill et al, 2012;Fauchez et al, 2014) from small scale (a few metres) to the "integral scale" or the outer scale (few tenths of a kilometre to one-hundred kilometres), where the spectrum becomes flat (i.e. decorrelation occurs).…”

Section: Introductionmentioning

confidence: 99%

A flexible three-dimensional stratocumulus, cumulus and cirrus cloud generator (3DCLOUD) based on drastically simplified atmospheric equations and Fourier transform framework

Szczap¹,

Gour²,

Fauchez³

et al. 2014

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. The 3DCLOUD algorithm for generating stochastic three-dimensional (3-D) cloud fields is described in this paper. The generated outputs are 3-D optical depth (τ) for stratocumulus and cumulus fields and 3-D ice water content (IWC) for cirrus clouds. This model is designed to generate cloud fields that share some statistical properties observed in real clouds such as the inhomogeneity parameter ρ (standard deviation normalized by the mean of the studied quantity), the Fourier spectral slope β close to −5/3 between the smallest scale of the simulation to the outer Lout (where the spectrum becomes flat). Firstly, 3DCLOUD assimilates meteorological profiles (humidity, pressure, temperature and wind velocity). The cloud coverage C, defined by the user, can also be assimilated, but only for stratocumulus and cumulus regime. 3DCLOUD solves drastically simplified basic atmospheric equations, in order to simulate 3-D cloud structures of liquid or ice water content. Secondly, Fourier filtering method is used to constrain intensity of ρ, β, Lout and mean of τ or IWC of these 3-D cloud structures. 3DCLOUD model was developed to run on a personnel computer under Matlab environment with the Matlab statistics toolbox. It is used to study 3-D interactions between cloudy atmosphere and radiation.

show abstract

Evaluation of cloud heterogeneity effects on total and polarized visible radiances as measured by POLDER/PARASOL and consequences for retrieved cloud properties

Cited by 6 publications

References 8 publications

A flexible three-dimensional stratocumulus, cumulus and cirrus cloud generator (3DCLOUD) based on drastically simplified atmospheric equations and the Fourier transform framework

A flexible three-dimensional stratocumulus, cumulus and cirrus cloud generator (3DCLOUD) based on drastically simplified atmospheric equations and the Fourier transform framework

Absorption of aerosols above clouds from POLDER/PARASOL measurements and estimation of their Direct Radiative Effect

A flexible three-dimensional stratocumulus, cumulus and cirrus cloud generator (3DCLOUD) based on drastically simplified atmospheric equations and Fourier transform framework

Contact Info

Product

Resources

About