2D image population analysis

Duroure, Christophe; Larsen, Howard; Isaka, Harumi; Personne, Pascal

doi:10.1016/0169-8095(94)90091-4

Cited by 18 publications

(15 citation statements)

References 4 publications

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“…Our experience from the observation of replicas is that the small particles tend to be of relatively simple form, but this result is at present unquantifed. Certainly at larger sizes an increasing complexity with increasing size has been documented in cumuliform ice clouds (Duroure et al, 1994) and a similar e ect may be expected in cirrus.…”

Section: Small Particle Shapementioning

confidence: 99%

“…This limitation a ects the con®dence which can be placed in both the description of particle shapes present, and the estimates of size ± integrated quantities such as ice water content. While recent analysis techniques o er some improvement (Duroure et al, 1994;Fouilloux et al, 1997), the accuracy of estimates of derived quantities sensitive to particle shape, such as radiative parameters and mass-integral quantities, remains limited. …”

Section: Pms 2d-c Probementioning

confidence: 99%

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Measurement errors in cirrus cloud microphysical properties

et al. 1998

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Abstract. The limited accuracy of current cloud microphysics sensors used in cirrus cloud studies imposes limitations on the use of the data to examine the cloud's broadband radiative behaviour, an important element of the global energy balance. We review the limitations of the instruments, PMS probes, most widely used for measuring the microphysical structure of cirrus clouds and show the e ect of these limitations on descriptions of the cloud radiative properties. The analysis is applied to measurements made as part of the European Cloud and Radiation Experiment (EUCREX) to determine mid-latitude cirrus microphysical and radiative properties.

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Section: Small Particle Shapementioning

confidence: 99%

Section: Pms 2d-c Probementioning

confidence: 99%

Measurement errors in cirrus cloud microphysical properties

et al. 1998

View full text Add to dashboard Cite

show abstract

“…This limitation aects the con®dence which can be placed in both the description of particle shapes present, and the estimates of size ± integrated quantities such as ice water content. While recent analysis techniques oer some improvement (Duroure et al, 1994;Fouilloux et al, 1997), the accuracy of estimates of derived quantities sensitive to particle shape, such as radiative parameters and mass-integral quantities, remains limited. …”

Section: Pms 2d-c Probementioning

confidence: 99%

“…Duroure et al, 1994). The techniques of data analysis involve intensive computer use but even so, are able to identify reliably only relatively regular crystal shapes.…”

Section: Pms 2d-c Probementioning

confidence: 99%

“…Typically the probe covers a particle size range of 25±800 lm with a pixel size of 25 lm. The analysis techniques use speci®c algorithms applied to the image of each particle to identify that particle's shape and size (Heyms®eld and Parrish, 1978;Duroure, 1982;Heyms®eld and Baumgardner, 1985;Duroure et al, 1994;Fouilloux et al, 1997) and to determine particle concentration.…”

Section: Pms 2d-c Probementioning

confidence: 99%

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Measurement errors in cirrus cloud microphysical properties

et al. 1998

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Abstract. The limited accuracy of current cloud microphysics sensors used in cirrus cloud studies imposes limitations on the use of the data to examine the cloud's broadband radiative behaviour, an important element of the global energy balance. We review the limitations of the instruments, PMS probes, most widely used for measuring the microphysical structure of cirrus clouds and show the eect of these limitations on descriptions of the cloud radiative properties. The analysis is applied to measurements made as part of the European Cloud and Radiation Experiment (EUCREX) to determine mid-latitude cirrus microphysical and radiative properties.

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Evaluation of key microphysical parameters in three‐dimensional cloud‐model simulations using aircraft and multiparameter radar data

Brown

Swann

1997

Quart J Royal Meteoro Soc

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A 3-d numerical model is being used for the development of improved parametrizations of convective transport processes in climate and numerical weather-prediction models. In common with similar cloud-resolving models, it uses a 3-phase bulk-water parametrization of the microphysical processes. The comparison of results from such models with observed case-studies represents an important step in their development and a key activity of the Global Energy and Water Cycle Experiment Cloud System Study.This paper presents observations and model results from the case of a weakly convective precipitating cloud that occurred on 22 June 1990 over central southern England. The cloud was observed by both an instrumented research aircraft and a dual-polarization radar. The combination of these measurements provides information on the dominant precipitation particle types, their density, number concentration, and characteristic size, and enables the identification of key microphysical processes. The observations were used to provide guidance on the numerical values of some of the variable parameters in the microphysics scheme. Observed values of No,G, the intercept parameter for graupel, lay in the range lo4 to lo7 m-4. The comparison of observed radar reflectivities with those calculated from in situ particle size spectra suggests that the density of rimed precipitation particles decreased from around 0.5 g cm-3 in the most intense precipitation to around 0.1 g A number of model sensitivity studies were performed to examine the impact of changes in these parameters on the model cloud and precipitation fields. For this case-study, it was found that the total surface precipitation was generally insensitive to such changes, varying by less than 10%. Reductions of 35% occurred for model tuns in which the graupel fall speed was reduced and for a model run with only 'warm-rain' microphysics. Much larger variations in the range 50-100% occurred in the total cloud ice and snow contents.The modelling study identifies a number of differences between runs which could not be resolved owing to the lack of in situ data in certain regions of the cloud. Some of the requirements for improved observational methods and procedures are discussed.towards the cloud edges.

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2D image population analysis

Cited by 18 publications

References 4 publications

Measurement errors in cirrus cloud microphysical properties

Measurement errors in cirrus cloud microphysical properties

Measurement errors in cirrus cloud microphysical properties

Evaluation of key microphysical parameters in three‐dimensional cloud‐model simulations using aircraft and multiparameter radar data

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