Solar Radiative Transfer in Cirrus Clouds. Part I: Single-Scattering and Optical Properties of Hexagonal Ice Crystals

Takano, Y.; Liou, Kuo‐Nan

doi:10.1175/1520-0469(1989)046<0003:srticc>2.0.co;2

Cited by 465 publications

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“…Optical phenomena such as the 22 • halo (and 46 • halo) were first explained by Mariotte (1717) as being due to the refraction of light (in the visible) by randomly oriented hexagonal ice crystals. Modelling studies of scattering phase functions show that these features are an indication of highly regular pristine ice crystals (see among others Takano and Liou, 1989;Iaquinta et al, 1995;Macke et al, 1996a;Yang et al, 2001;Um and McFarquhar, 2010). Observations of cloud ice particles tend to show much smoother scattering behaviour compared with modelling results obtained in laboratory studies (Sassen and Liou, 1979;Crépel et al, 1997;Barkey et al, 2002).…”

Section: Introductionmentioning

confidence: 86%

Optical properties of pristine ice crystals in mid-latitude cirrus clouds: a case study during CIRCLE-2 experiment

et al. 2011

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Abstract. In this paper, we describe in situ observations of mid-latitude cirrus cloud band carried out on 16 May 2007 during the CIRCLE-2 experiment. The Polar Nephelometer and the Cloud Particle Imager (CPI) instruments with PMS FSSP-300 and 2D-C probes were used for the description of the optical and microphysical cloud properties. Two selected cloud regions are compared and discussed in detail. Significant differences in optical properties are evidenced in terms of 22 • halo occurrences even though prevalent planarplate ice crystals are observed in both cloud regions. Featureless scattering phase functions are measured in the first cloud region located near the trailing edge of the cirrus-band at about 11 800 m/−57 • C. In contrast, well pronounced 22 • halo peaks are observed with predominant similar-shaped ice crystals near the cirrus-band leading edge at 7100 m/−27 • C. CPI ice crystal images with Polar Nephelometer observations are carefully analysed and interpreted from a theoretical light scattering model in order to explain occurrence and non-occurrence of the 22 • halo feature. The results highlight that the halo peaks are inherent only in perfect plate ice crystals (or pristine crystals). On the basis of previous datasets in mid-latitude cirrus, it is found that simple pristine crystals are uncommon whereas particles with imperfect or complex shapes are prevalent. As a result, phase functions that are smooth and featureless best represent cirrus scattering properties.

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Section: Introductionmentioning

confidence: 86%

Optical properties of pristine ice crystals in mid-latitude cirrus clouds: a case study during CIRCLE-2 experiment

et al. 2011

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“…Simplified representations of the scattering properties of randomly oriented irregularly shaped particles have been sought by treating those particles as equivalent spheres using Lorenz-Mie theory; see, for example, Takano and Liou (1989), Grenfell and Warren (1999), and Liu (2004). Unfortunately that approach has been hobbled because of the numerous criteria for defining the equivalent diameters, that is, equivalent volumes, surface areas, projected areas, ratios of volume to surface area, or spheres with diameters equal to the large dimension, but with reduced refractive indices.…”

Section: Introductionmentioning

confidence: 99%

A Simple Model of the Millimeter-Wave Scattering Parameters of Randomly Oriented Aggregates of Finite Cylindrical Ice Hydrometeors

Weinman

Kim

2007

Journal of the Atmospheric Sciences

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Spaceborne millimeter-wave radiometric measurements offer the potential to observe snowfall at high latitudes. A spaceborne W-band cloud radar on CloudSat has been able to observe snow. There is thus a need for a relatively simple representation of millimeter-wave scattering parameters of snow that can be incorporated into algorithms to retrieve snowfall from remotely sensed millimeter-wave brightness temperature measurements and for computing the millimeter-wave backscatter phase function of randomly oriented aggregates of ice prisms or columns.The extinction coefficients, asymmetry factors, and backscatter phase functions describing scattering by randomly oriented aggregates of elongated cylinders were computed from the discrete dipole approximation. These parameters were also computed by means of a T-matrix model applied to single blunt cylinders by employing a phase delay that only depended on the frequency and the ratio of the volume to the projected area of the cylindrical aggregates. These scattering parameters were fitted by empirical analytical functions that only depended on that phase delay. This permitted consideration of numerous aggregate shapes with far less computational effort than that required by the discrete dipole approximation.The results of this analysis were applied to measurements of millimeter-wave extinction, radar reflectivity, and snow size distributions obtained during the SNOW-TWO field experiment conducted by the U.S. Army in 1984. Although the simultaneity of the various measurements was not well documented, the theoretical results fell within the range of measurement uncertainty. Model results of the extinction coefficient and asymmetry factor needed to compute 183-GHz brightness temperatures measured by the NOAA Advanced Microwave Sounding Unit-B (AMSU-B) radiometers are presented in the appendix.

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“…An error of 3 to 4% in the calibration constant causes 0.03 to 0.04 change at most to the optical thickness. We used the phase function calculated by Takano and Liou (1989). The size distributions of ice crystals measured by the HYVIS are close to that assumed by Takano and Liou (1989).…”

Section: Observational Results By Radiometersmentioning

confidence: 75%

“…We used the phase function calculated by Takano and Liou (1989). The size distributions of ice crystals measured by the HYVIS are close to that assumed by Takano and Liou (1989). Therefore, the optical thickness estimated has no serious error.…”

Section: Observational Results By Radiometersmentioning

confidence: 77%

Ground-Based Cirrus Observation

Uchiyama¹,

Asano²,

Shiobara

et al. 1999

Journal of the Meteorological Society of Japan

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Solar Radiative Transfer in Cirrus Clouds. Part I: Single-Scattering and Optical Properties of Hexagonal Ice Crystals

Cited by 465 publications

References 0 publications

Optical properties of pristine ice crystals in mid-latitude cirrus clouds: a case study during CIRCLE-2 experiment

Optical properties of pristine ice crystals in mid-latitude cirrus clouds: a case study during CIRCLE-2 experiment

A Simple Model of the Millimeter-Wave Scattering Parameters of Randomly Oriented Aggregates of Finite Cylindrical Ice Hydrometeors

Ground-Based Cirrus Observation

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