scholarly journals Global analysis of cloud phase and ice crystal orientation from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data using attenuated backscattering and depolarization ratio

2010 ◽  
Vol 115 ◽  
Author(s):  
R. Yoshida ◽  
H. Okamoto ◽  
Y. Hagihara ◽  
H. Ishimoto
Keyword(s):  
Crystal Orientation ◽  
Global Analysis ◽  
Satellite Observation ◽  
Depolarization Ratio ◽  
Ice Crystal

scholarly journals Falling Mixed-Phase Ice Virga and their Liquid Parent Cloud Layers as Observed by Ground-Based Lidars

2020 ◽  
Vol 12 (13) ◽  
pp. 2094
Author(s):  
Chong Cheng ◽  
Fan Yi
Keyword(s):  
Local Maximum ◽  
Water Layer ◽  
Supercooled Liquid ◽  
Mixed Phase ◽  
Ice Crystals ◽  
Cloud Base ◽  
Depolarization Ratio ◽  
Ice Crystal ◽  
Liquid Drops ◽  
The Mean

Falling mixed-phase virga from a thin supercooled liquid layer cloud base were observed on 20 occasions at altitudes of 2.3–9.4 km with ground-based lidars at Wuhan (30.5 °N, 114.4 °E), China. Polarization lidar profile (3.75-m) analysis reveals some ubiquitous features of both falling mixed-phase virga and their liquid parent cloud layers. Each liquid parent cloud had a well-defined base height where the backscatter ratio R was ~7.0 and the R profile had a clear inflection point. At an altitude of ~34 m above the base height, the depolarization ratio reached its minimum value (~0.04), indicating a liquid-only level therein. The thin parent cloud layers tended to form on the top of a broad preexisting aerosol/liquid water layer. The falling virga below the base height showed firstly a significant depolarization ratio increase, suggesting that most supercooled liquid drops in the virga were rapidly frozen into ice crystals (via contact freezing). After reaching a local maximum value of the depolarization ratio, both the values of the backscatter ratio and depolarization ratio for the virga exhibited an overall decrease with decreasing height, indicating sublimated ice crystals. The diameters of the ice crystals in the virga were estimated based on an ice particle sublimation model along with the lidar and radiosonde observations. It was found that the ice crystal particles in these virga cases tended to have smaller mean diameters and narrower size distributions with increasing altitude. The mean diameter value is 350 ± 111 µm at altitudes of 4–8.5 km.

402 Investigation on influence of surface roughness of cooling surface on ice structure formed by control of initial ice crystal orientation

2014 ◽  
Vol 2014.24 (0) ◽  
pp. 121-122
Author(s):  
Takahiro IKEYA ◽  
Koji MATSUMOTO ◽  
Yoshikazu TERAOKA ◽  
Kazuyoshi MATSUNAGA ◽  
Masato HONDA
Keyword(s):  
Surface Roughness ◽  
Crystal Orientation ◽  
Ice Crystal ◽  
Cooling Surface

Crystal Orientation Rotation of Ice During Growth in a Bended Capillary

2011 ◽  
Author(s):  
Yoshikazu Teraoka ◽  
Ryo Fukuno ◽  
Koji Matsumoto
Keyword(s):  
Empirical Model ◽  
Crystal Orientation ◽  
High Rate ◽  
Control Technique ◽  
Ice Crystal ◽  
Ice Growth ◽  
Before And After ◽  
Supercooling Temperature

A control technique of crystal orientation of ice can presumably help to improve freezing processes of various industries. However, the technique without seed ice has not been established yet. The author had found that crystal orientation of ice rotated gradually during high-rate growth along a cooling wall. The purpose of this paper is to examine the crystal orientation rotation of ice during growth in several types of bended capillaries at supercooling temperature. We show that, after growing through the capillaries, c-axis of ice crystal is within a certain angle range. On the basis of the measurement the rotation of crystal orientation before and after the growth through some sections of the capillaries, we constructed an empirical model of c-axis rotating gradually during ice growth in the capillary. The calculation of the model can explain the approach process of c-axis of ice crystal growing in the bended capillary to the specified direction.

scholarly journals Canadian Biomass Burning Aerosol Properties Modification during a Long-Ranged Event on August 2018

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5442
Author(s):  
Christina-Anna Papanikolaou ◽  
Elina Giannakaki ◽  
Alexandros Papayannis ◽  
Maria Mylonaki ◽  
Ourania Soupiona
Keyword(s):  
Biomass Burning ◽  
Remote Sensing Data ◽  
Satellite Observation ◽  
Depolarization Ratio ◽  
Marine Aerosols ◽  
Backscatter Coefficient ◽  
Biomass Burning Aerosol ◽  
The Mean ◽  
Spatio Temporal ◽  
Aerosol Backscatter

The aim of this paper is to study the spatio-temporal evolution of a long-lasting Canadian biomass burning event that affected Europe in August 2018. The event produced biomass burning aerosol layers which were observed during their transport from Canada to Europe from the 16 to the 26 August 2018 using active remote sensing data from the space-borne system Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The total number of aerosol layers detected was 745 of which 42% were identified as pure biomass burning. The remaining 58% were attributed to smoke mixed with: polluted dust (34%), clean continental (10%), polluted continental (5%), desert dust (6%) or marine aerosols (3%). In this study, smoke layers, pure and mixed ones, were observed by the CALIPSO satellite from 0.8 and up to 9.6 km height above mean sea level (amsl.). The mean altitude of these layers was found between 2.1 and 5.2 km amsl. The Ångström exponent, relevant to the aerosol backscatter coefficient (532/1064 nm), ranged between 0.9 and 1.5, indicating aerosols of different sizes. The mean linear particle depolarization ratio at 532 nm for pure biomass burning aerosols was found equal to 0.05 ± 0.04, indicating near spherical aerosols. We also observed that, in case of no aerosol mixing, the sphericity of pure smoke aerosols does not change during the air mass transportation (0.05–0.06). On the contrary, when the smoke is mixed with dessert dust the mean linear particle depolarization ratio may reach values up to 0.20 ± 0.04, especially close to the African continent (Region 4).

scholarly journals Complete determination of ice crystal orientation using Laue X-ray diffraction method

2011 ◽  
Vol 57 (201) ◽  
pp. 103-110 ◽  
Author(s):  
Atsushi Miyamoto ◽  
Ilka Weikusat ◽  
Takeo Hondoh
Keyword(s):  
Crystal Orientation ◽  
Ice Core ◽  
Ice Sheets ◽  
Diffraction Method ◽  
Ice Cores ◽  
Ice Crystals ◽  
Ice Crystal ◽  
X Ray Diffraction ◽  
Axis Orientation ◽  
X Ray

AbstractIce crystal orientation fabric data from ice cores contain important information concerning the internal structure and the flow behaviour of ice sheets. When ice cores are recovered from the Antarctic and Greenland ice sheets, crystal orientation measurements are performed immediately to obtain fundamental physical property information. In the past, we have measured the c-axis orientation of ice crystals by a manual optical method using a universal stage. This method is very time-consuming, involving tedious work in a cold laboratory. Recently, automated systems have been developed that enable measurement of c-axis orientation, grain size and other microstructures. However, in order to detect the full crystal orientation of an ice crystal, we also need information on its a-axis orientation. A variety of other crystal orientation measurement methods have previously been discussed, but some shortcomings for ice-core studies cannot be neglected. We have developed a crystal-orientation analysing device using the Laue X-ray diffraction method. As this device can measure the orientations of all crystal axes with high accuracy, it is possible to obtain new microstructure information on natural ice crystals. For the first time, we are able to quantify very low subgrain misorientation angles in polar ice-core samples, allowing us to investigate micro-deformation features of individual crystals. Here we discuss the analysis process, which is customized to measure standard ice thin sections, and show preliminary results.

scholarly journals Radar characterization of ice crystal orientation fabric and anisotropic rheology within an Antarctic ice stream

2020 ◽  
Author(s):  
Thomas Jordan ◽  
Carlos Martin ◽  
Alex Brisbourne ◽  
Dustin Schroeder ◽  
Andrew Smith
Keyword(s):  
Crystal Orientation ◽  
Ice Crystal ◽  
Ice Stream

scholarly journals Classification of Ice Crystal Shapes in Midlatitude Ice Clouds from Three Years of Lidar Observations over the SIRTA Observatory

2006 ◽  
Vol 63 (11) ◽  
pp. 2978-2991 ◽  
Author(s):  
Vincent Noel ◽  
Helene Chepfer ◽  
Martial Haeffelin ◽  
Yohann Morille
Keyword(s):  
Relative Concentration ◽  
Strong Dependence ◽  
Depolarization Ratio ◽  
Ice Crystal ◽  
Jet Streams ◽  
Ice Clouds ◽  
Wind Speeds ◽  
Crystal Shapes ◽  
Microphysical Properties ◽  
Aspect Ratios

Abstract This paper presents a study of ice crystal shapes in midlatitude ice clouds inferred from a technique based on the comparison of ray-tracing simulations with lidar depolarization ratio measured at 532 nm. This technique is applied to three years of lidar depolarization ratio observations from the Site Instrumental de Recherche par Télédétection Atmosphérique (SIRTA) observatory in Palaiseau, France, amounting to 322 different days of ice cloud observations. Particles in clouds are classified in three major groups: plates, columns, and irregular shapes with aspect ratios close to unity. Retrieved shapes are correlated with radiosounding observations from a close-by meteorological station: temperature, relative humidity, wind speed, and direction. Results show a strong dependence of the relative concentration of different crystal shapes to most atmospheric variables, such as the temperature, with a clear successive dominance by platelike (temperature above −20°C), irregular (temperatures between −60° and −40°C), and columnlike shapes (temperatures below −60°C). Particle shapes are almost exclusively columnlike below −75°C. This is in sharp contrast with previous results of the same classification applied to tropical clouds, and highlights the high geographic variability of the ice clouds distribution of microphysical properties. Results also suggest that ice clouds created by jet streams (identified by high wind speeds) are strongly dominated by columnlike shapes, while front-created ice clouds (identified by lower wind speeds) show a much more variable mix of shapes, with the dominant shapes depending on other factors. Results also suggest different microphysical properties according to the average direction source of air masses and winds. Following these results, a possible parameterization of ice crystal shapes in midlatitude ice clouds as a function of temperature is provided.

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