Cloud detection and derivation of cloud properties from POLDER

Buriez, J. C.; Vanbauce, C.; Parol, Frédéric; Goloub, Philippe; Herman, M.; Bonnel, B.; Fouquart, Y.; Couvert, P.; Sèze, Geneviève

doi:10.1080/014311697217332

Cited by 150 publications

(122 citation statements)

References 27 publications

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“…Cloud top pressure is derived from the cloud oxygen pressure (Bréon and Colzy, 1999). Cloud top pressure retrieved by POLDER-3 appears to be a better proxy for low-level cloud height than MODIS cloud top pressure derived using a thermal signature assuming a given temperature profile (Buriez et al, 1997;Weisz et al, 2007;Tietze et al, 2011;Desmons et al, 2013).…”

Section: Satellite Cloud Property Retrievalsmentioning

confidence: 99%

Effects of long-range aerosol transport on the microphysical properties of low-level liquid clouds in the Arctic

et al. 2016

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Abstract. The properties of low-level liquid clouds in the Arctic can be altered by long-range pollution transport to the region. Satellite, tracer transport model, and meteorological data sets are used here to determine a net aerosol-cloud interaction (ACI net ) parameter that expresses the ratio of relative changes in cloud microphysical properties to relative variations in pollution concentrations while accounting for dry or wet scavenging of aerosols en route to the Arctic. For a period between 2008 and 2010, ACI net is calculated as a function of the cloud liquid water path, temperature, altitude, specific humidity, and lower tropospheric stability. For all data, ACI net averages 0.12±0.02 for cloud-droplet effective radius and 0.16±0.02 for cloud optical depth. It increases with specific humidity and lower tropospheric stability and is highest when pollution concentrations are low. Carefully controlling for meteorological conditions we find that the liquid water path of arctic clouds does not respond strongly to aerosols within pollution plumes. Or, not stratifying the data according to meteorological state can lead to artificially exaggerated calculations of the magnitude of the impacts of pollution on arctic clouds.

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Section: Satellite Cloud Property Retrievalsmentioning

confidence: 99%

Effects of long-range aerosol transport on the microphysical properties of low-level liquid clouds in the Arctic

et al. 2016

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“…The polarized intensity Ip defined by the square root of ͑Q 2 ϩ U 2 ͒, where Q and U are Stokes parameters, is analyzed and for such selected acquisitions, Ip derived by the radiometric model inversion is expected to be null if is well calibrated. Signal observed over bright scattered clouds (targets used for the interband calibration) for a specific scattering angle near 160°is unpolarized whatever the microphysics of the clouds: ice crystal or water droplet particles [32]. Assuming that the polarizer efficiency (see Subsection 2.A) is perfectly known from preflight characterization, this property was used as illustrated in Fig.…”

Section: In-polarization Calibrationmentioning

confidence: 99%

PARASOL in-flight calibration and performance

et al. 2007

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Since 18 December 2004, the PARASOL satellite is a member of the so-called A-train atmospheric orbital observatory, flying together with Aqua, Aura, CALIPSO, CLOUDSAT, and OCO satellites. These satellites combine for the first time a full suite of instruments for observing aerosols and clouds, using passive radiometer complementarily with active lidar and radar sounders. The PARASOL payload is extensively derived from the instrument developed for the POLDER programs that performs measurements of bidirectionality and polarization for a very wide field-of-view and for a visible͞near-infrared spectral range. An overview of the results obtained during the commissioning phase and the reevaluation after one year in orbit is presented. In-flight calibration methods are briefly described, and radiometric and geometric performances are both evaluated. All algorithms are based on a panel of methods using mainly natural targets previously developed for POLDER missions and adapted or redeveloped in the PARASOL context. Regarding performances, all mission requirements are met except for band 443 (not recommended for use). After one year in orbit, a perfect geometrical stability was found while a slight decrease of the radiometric sensitivity was observed and corrected through an innovative multitemporal algorithm based on observations of bright and scattered convective clouds. The scientific exploitation of PARASOL has now begun, particularly by coupling these specific observations with other A-train sensor measurements.

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“…A description of the POLDER instrument can be found in Buriez et al (1997). The POLDER-2 instrument was launched on 14 December 2002 onboard the satellite platform ADEOS-2 (Advanced Earth Observing Satellite) and was operational until October 2003.…”

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

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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Cloud detection and derivation of cloud properties from POLDER

Cited by 150 publications

References 27 publications

Effects of long-range aerosol transport on the microphysical properties of low-level liquid clouds in the Arctic

Effects of long-range aerosol transport on the microphysical properties of low-level liquid clouds in the Arctic

PARASOL in-flight calibration and performance

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

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