Single Scattering Properties of Atmospheric Ice Crystals

Macke, Andreas; Mueller, Johannes; Raschke, E.

doi:10.1175/1520-0469(1996)053<2813:sspoai>2.0.co;2

Cited by 465 publications

(459 citation statements)

References 6 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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“…Air bubble inclusion also plays an important role in causing the difference in g between the two models, for it is known that nonabsorbing inclusions, such as air bubbles, reduces forwardscattering and increases the side and back-scattering (Macke et al, 1996a). Both fractal and roughened surfaces can also have effects on the scattering properties of ice particles similar to air bubble inclusion, i.e., smoothing out scattering features and reducing the asymmetry factor (Macke et al, 1996b;Yang et al, 2008).…”

Section: Modis and Polder Ice Optical Thickness Retrieval Algorithmsmentioning

confidence: 99%

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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“…Since initial work that identified crystal shapes using in situ ob-servations of ice clouds (e.g., Weickmann, 1948, and studies summarized by Dowling and Radke, 1990, and by Heymsfield and McFarquhar, 2002), much effort has been devoted to quantify the microphysical and scattering properties of ice crystals. One important finding is that ambient atmospheric conditions (e.g., temperature and humidity) govern the growth and morphological properties of ice crystals (e.g., aufm Kampe et al, 1951;Lamb and Scott, 1974;Gonda, 1980;Fukuta and Takahashi, 1999;Bacon et al, 2003;Bailey and Hallett, 2002, 2012Korolev et al, 2004) upon which the corresponding scattering properties depend (e.g., Takano and Liou, 1995;Macke et al, 1996;Yang and Liou, 1998;Baran et al, 2001Baran et al, , 2005Yang et al, 2005Yang et al, , 2013Um and McFarquhar, 2007.…”

Section: Introductionmentioning

confidence: 99%

“…Prior studies have shown that the assumed L-W relationship impacts the single-scattering properties of ice crystals (Macke et al, 1996, Um and McFarquhar, 2007Yang and Fu, 2009;van Diedenhoven et al, 2014a), satellite retrievals (Han et al, 1999), and numerical simulations (Fu, 2007;Sheridan et al, 2009;Sulia and Harrington, 2011;Dearden et al, 2012). In addition, new modeling approaches (e.g., Sulia and Harrington, 2011) that explicitly predict particle properties rather than using predefined ice categories as in traditional schemes require statistical databases of L and W .…”

Section: Introductionmentioning

confidence: 99%

Dimensions and aspect ratios of natural ice crystals

McFarquhar

Hong

et al. 2015

Atmos. Chem. Phys.

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Abstract. During the 2006 Tropical Warm Pool InternationalCloud Experiment (TWP-ICE) in the tropics, the 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) in the Arctic, and the 2010 Small PARTicles In CirrUS (SPAR-TICUS) campaign at mid-latitudes, high-resolution images of ice crystals were recorded by a Cloud Particle Imager at temperatures (T ) between −87 and 0 • C. The projected maximum dimension (D ), length (L ), and width (W ) of pristine columns, plates, and component bullets of bullet rosettes were measured using newly developed software, the Ice Crystal Ruler. The number of bullets in each bullet rosette was also measured. Column crystals were further distinguished as either horizontally oriented columns or columns with other orientations to eliminate any orientation effect on the measured dimensions. The dimensions and aspect ratios (AR, the dimension of the major axis divided by the dimension of the minor axis) of crystals were determined as functions of temperature, geophysical location, and type of cirrus.Dimensions of crystals generally increased with temperature. Columns and bullets had larger dimensions (i.e., W ) of the minor axis (i.e., a axis) for a given dimension (i.e., D or L ) of the major axis (i.e., c axis), and thus smaller AR, as T increased, whereas this trend did not occur for plate crystals. The average number of branches in bullet rosettes was 5.50 ± 1.35 during three campaigns and 6.32 ± 1.34 (5.46 ± 1.34; 4.95 ± 1.01) during TWP-ICE (SPARTICUS; ISDAC). The AR of bullets increased with the number of branches in bullet rosettes. Most dimensions of crystals and ARs of columnar crystals measured during SPARTICUS were larger than those measured during TWP-ICE and IS-DAC at −67 < T < −35 • C and at −40 < T < −15 • C, respectively. The relative occurrence of varying pristine habits depended strongly on cirrus type (i.e., anvil or non-anvil clouds), with plates especially occurring more frequently in anvils. The L-W relationships of columns derived using current data exhibited a strong dependence on temperature; similar relationships determined in previous studies were within the range of the current data.

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Single Scattering Properties of Atmospheric Ice Crystals

Cited by 465 publications

References 6 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

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

Dimensions and aspect ratios of natural ice crystals

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