Optical properties of the cirrus cloud ice crystals with preferred azimuthal orientation for polarization lidars with azimuthal scanning

2016 ◽  
Author(s):  
Alexander V. Konoshonkin ◽  
Natalia V. Kustova ◽  
Sergey V. Nasonov ◽  
Ilia D. Bryukhanov ◽  
Viktor A. Shishko ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ice Crystals ◽  
Cirrus Cloud ◽  
Cloud Ice

Modeling, simulation, and comparison study of cirrus cloud ice crystals

2003 ◽  
Author(s):  
Jorge M. Villa ◽  
Sandra L. Cruz-Pol ◽  
Jose G. Colom-Ustariz ◽  
Stephen M. Sekelsky
Keyword(s):  
Ice Crystals ◽  
Cirrus Cloud ◽  
Comparison Study ◽  
Modeling Simulation ◽  
Cloud Ice

scholarly journals CALIPSO (IIR–CALIOP) retrievals of cirrus cloud ice-particle concentrations

2018 ◽  
Vol 18 (23) ◽  
pp. 17325-17354 ◽  
Author(s):  
David L. Mitchell ◽  
Anne Garnier ◽  
Jacques Pelon ◽  
Ehsan Erfani
Keyword(s):  
Remote Sensing ◽  
Satellite Remote Sensing ◽  
Ice Crystals ◽  
Cloud Base ◽  
Effective Diameter ◽  
Cirrus Cloud ◽  
Base Temperature ◽  
High Latitudes ◽  
Cloud Ice

Abstract. A new satellite remote sensing method is described whereby the sensitivity of thermal infrared wave resonance absorption to small ice crystals is exploited to estimate cirrus cloud ice-particle number concentration N, effective diameter De and ice water content IWC. This method uses co-located observations from the Infrared Imaging Radiometer (IIR) and from the CALIOP (Cloud and Aerosol Lidar with Orthogonal Polarization) lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) polar orbiting satellite, employing IIR channels at 10.6 and 12.05 µm. Using particle size distributions measured over many flights of the TC4 (Tropical Composition, Cloud and Climate Coupling) and the mid-latitude SPARTICUS (Small Particles in Cirrus) field campaigns, we show for the first time that N∕IWC is tightly related to βeff; the ratio of effective absorption optical depths at 12.05 and 10.6 µm. Relationships developed from in situ aircraft measurements are applied to βeff derived from IIR measurements to retrieve N. This satellite remote sensing method is constrained by measurements of βeff from the IIR and is by essence sensitive to the smallest ice crystals. Retrieval uncertainties are discussed, including uncertainties related to in situ measurement of small ice crystals (D<15 µm), which are studied through comparisons with IIR βeff. The method is applied here to single-layered semi-transparent clouds having a visible optical depth between about 0.3 and 3, where cloud base temperature is ≤235 K. CALIPSO data taken over 2 years have been analyzed for the years 2008 and 2013, with the dependence of cirrus cloud N and De on altitude, temperature, latitude, season (winter vs. summer) and topography (land vs. ocean) described. The results for the mid-latitudes show a considerable dependence on season. In the high latitudes, N tends to be highest and De smallest, whereas the opposite is true for the tropics. The frequency of occurrence of these relatively thick cirrus clouds exhibited a strong seasonal dependence in the high latitudes, with the occurrence frequency during Arctic winter being at least twice that of any other season. Processes that could potentially explain some of these micro- and macroscopic cloud phenomena are discussed.

scholarly journals On the Occurrence of Hollow Bullet Rosette– and Column-Shaped Ice Crystals in Midlatitude Cirrus

2007 ◽  
Vol 64 (12) ◽  
pp. 4514-4519 ◽  
Author(s):  
C. G. Schmitt ◽  
A. J. Heymsfield
Keyword(s):  
Cirrus Clouds ◽  
Ice Crystals ◽  
Radiative Properties ◽  
Cirrus Cloud ◽  
Ice Crystal ◽  
Particle Size Distributions ◽  
Polyvinyl Formal ◽  
Ice Particles ◽  
Cloud Ice ◽  
Parameter Values

Abstract Cirrus clouds in mid- and high latitudes are frequently composed of bullet rosette– and column-shaped ice crystals, which can have hollow ends. Bullet rosette–shaped ice crystals are composed of a number of bullets radiating from a central point. Research has shown that the light-scattering properties of ice particles with hollow ends are different from the scattering properties of solid ice particles. Knowledge of the frequency of occurrence of hollow particles is important to more accurately calculate the radiative properties of cirrus clouds. This note presents the results of a survey of cirrus cloud ice crystal replicas imaged from balloon-borne Formvar (polyvinyl formal) replicators. Fifty percent to 80% of the replicated bullet rosette– and column-shaped particles had hollow ends. In bullets longer than 150 μm in length, the length of the hollows of the bullets averaged 88% of the total length of the bullet. The combined length of both hollow portions of column-shaped ice crystals varied from 50% of the length of the column for 30-μm-long columns to 80% of the length of the columns longer than 200 μm. Asymmetry parameter values estimated from cirrus cloud aircraft particle size distributions are higher by 0.014 when hollow crystals are considered. This difference leads to a 2.5 W m−2 increase for hollow crystals at the surface for a 0.5 optical depth cloud, demonstrating the importance of the incorporation of hollow particle scattering characteristics into radiative transfer calculations.

scholarly journals CALIPSO (IIR-CALIOP) Retrievals of Cirrus Cloud Ice Particle Concentrations

2018 ◽  
Author(s):  
David L. Mitchell ◽  
Anne Garnier ◽  
Jacques Pelon ◽  
Ehsan Erfani
Keyword(s):  
Remote Sensing ◽  
Satellite Remote Sensing ◽  
Infrared Imaging ◽  
Ice Crystals ◽  
Orthogonal Polarization ◽  
Effective Diameter ◽  
Cirrus Cloud ◽  
Polar Orbiting Satellite ◽  
Cloud Ice

Abstract. A new satellite remote sensing method is described whereby the sensitivity of thermal infrared wave resonance absorption to small ice crystals is exploited to estimate cirrus cloud ice particle number concentration N, effective diameter De, and ice water content IWC. This method uses co-located observations from the Infrared Imaging Radiometer (IIR) and from the CALIOP (Cloud and Aerosol Lidar with Orthogonal Polarization) lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) polar orbiting satellite, employing IIR channels at 10.6 μm and 12.05 μm. Using particle size distributions measured over several flights of the TC4 (Tropical Composition, Cloud and Climate Coupling) and the mid-latitudes SPARTICUS (Small Particles in Cirrus) field campaigns, we show for the first time that N/IWC is tightly related to βeff; the ratio of effective absorption optical depths at 12.05 μm and 10.6 μm. Relationships developed from in situ aircraft measurements are applied to βeff derived from IIR measurements to retrieve N. This satellite remote sensing method is constrained by measurements of βeff from the IIR and is by essence sensitive to the smallest ice crystals. Retrieval uncertainties are discussed, including uncertainties related to in situ measurement of small ice crystals (D 

scholarly journals Simulating the influence of primary biological aerosol particles on clouds by heterogeneous ice nucleation

2018 ◽  
Vol 18 (20) ◽  
pp. 15437-15450 ◽  
Author(s):  
Matthias Hummel ◽  
Corinna Hoose ◽  
Bernhard Pummer ◽  
Caroline Schaupp ◽  
Janine Fröhlich-Nowoisky ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Aerosol Particles ◽  
Fungal Spores ◽  
Ice Nucleation ◽  
Ice Crystals ◽  
Atmospheric Measurements ◽  
Cloud Ice ◽  
Biological Aerosol Particles ◽  
Ice Phase ◽  
Heterogeneous Ice Nucleation

Abstract. Primary ice formation, which is an important process for mixed-phase clouds with an impact on their lifetime, radiative balance, and hence the climate, strongly depends on the availability of ice-nucleating particles (INPs). Supercooled droplets within these clouds remain liquid until an INP immersed in or colliding with the droplet reaches its activation temperature. Only a few aerosol particles are acting as INPs and the freezing efficiency varies among them. Thus, the fraction of supercooled water in the cloud depends on the specific properties and concentrations of the INPs. Primary biological aerosol particles (PBAPs) have been identified as very efficient INPs at high subzero temperatures, but their very low atmospheric concentrations make it difficult to quantify their impact on clouds. Here we use the regional atmospheric model COSMO–ART to simulate the heterogeneous ice nucleation by PBAPs during a 1-week case study on a domain covering Europe. We focus on three highly ice-nucleation-active PBAP species, Pseudomonas syringae bacteria cells and spores from the fungi Cladosporium sp. and Mortierella alpina. PBAP emissions are parameterized in order to represent the entirety of bacteria and fungal spores in the atmosphere. Thus, only parts of the simulated PBAPs are assumed to act as INPs. The ice nucleation parameterizations are specific for the three selected species and are based on a deterministic approach. The PBAP concentrations simulated in this study are within the range of previously reported results from other modeling studies and atmospheric measurements. Two regimes of PBAP INP concentrations are identified: a temperature-limited and a PBAP-limited regime, which occur at temperatures above and below a maximal concentration at around −10 ∘C, respectively. In an ensemble of control and disturbed simulations, the change in the average ice crystal concentration by biological INPs is not statistically significant, suggesting that PBAPs have no significant influence on the average state of the cloud ice phase. However, if the cloud top temperature is below −15 ∘C, PBAP can influence the cloud ice phase and produce ice crystals in the absence of other INPs. Nevertheless, the number of produced ice crystals is very low and it has no influence on the modeled number of cloud droplets and hence the cloud structure.

scholarly journals MU Radar and Lidar Observations of Clear-Air Turbulence underneath Cirrus

2010 ◽  
Vol 138 (2) ◽  
pp. 438-452 ◽  
Author(s):  
Hubert Luce ◽  
Takuji Nakamura ◽  
Masayuki K. Yamamoto ◽  
Mamoru Yamamoto ◽  
Shoichiro Fukao
Keyword(s):  
Convective Instability ◽  
Radar Data ◽  
Ice Crystals ◽  
Shear Instability ◽  
Cloud Base ◽  
Doppler Spectrum ◽  
Cirrus Cloud ◽  
Air Turbulence ◽  
Mu Radar ◽  
Generation Mechanisms

Abstract Turbulence generation mechanisms prevalent in the atmosphere are mainly shear instabilities, breaking of internal buoyancy waves, and convective instabilities such as thermal convection due to heating of the ground. In the present work, clear-air turbulence underneath a cirrus cloud base is described owing to coincident observations from the VHF (46.5 MHz) middle and upper atmosphere (MU) radar, a Rayleigh–Mie–Raman (RMR) lidar, and a balloon radiosonde on 7–8 June 2006 (at Shigaraki, Japan; 34.85°N, 136.10°E). Time–height cross section of lidar backscatter ratio obtained at 2206 LT 7 June 2006 showed the presence of a cirrus layer between 8.0 and 12.5 km MSL. Downward-penetrating structures of ice crystals with horizontal and vertical extents of 1.0–4.0 km and 200–800 m, respectively, have been detected at the cirrus cloud base for about 35 min. At the same time, the MU radar data revealed clear-air turbulence layers developing downward from the cloud base in the environment of the protuberances detected by the RMR lidar. Their maximum depth was about 2.0 km for about 1.5 h. They were associated with oscillatory vertical wind perturbations of up to ±1.5 m s−1 and variances of Doppler spectrum of 0.2–1.5 m−2 s−2. Analysis of the data suggests that the turbulence and the downward penetration of cloudy air were possibly the consequence of a convective instability (rather than a dynamical shear instability) that was likely due to sublimation of ice crystals in the subcloud region. Downward clear-air motions measured by the MU radar were associated with the descending protuberances, and updrafts were observed between them. These observations suggest that the cloudy air might have been pushed down by the downdrafts of the convective instability and pushed up by the updrafts to form the observed protuberances at the cloud base. These structures may be virga or perhaps more likely mamma as reported by recent observations of cirrus mamma with similar instruments and by numerical simulations.

scholarly journals How frequent is natural cloud seeding from ice cloud layers ( < −35 °C) over Switzerland?

2021 ◽  
Vol 21 (6) ◽  
pp. 5195-5216
Author(s):  
Ulrike Proske ◽  
Verena Bessenbacher ◽  
Zane Dedekind ◽  
Ulrike Lohmann ◽  
David Neubauer
Keyword(s):  
Prediction Models ◽  
Water Cycle ◽  
Weather Prediction ◽  
Ice Crystals ◽  
Occurrence Frequency ◽  
Climate Projections ◽  
Cirrus Cloud ◽  
Cloud Seeding ◽  
Cloud Properties ◽  
Layer Cloud

Abstract. Clouds and cloud feedbacks represent one of the largest uncertainties in climate projections. As the ice phase influences many key cloud properties and their lifetime, its formation needs to be better understood in order to improve climate and weather prediction models. Ice crystals sedimenting out of a cloud do not sublimate immediately but can survive certain distances and eventually fall into a cloud below. This natural cloud seeding can trigger glaciation and has been shown to enhance precipitation formation. However, to date, an estimate of its occurrence frequency is lacking. In this study, we estimate the occurrence frequency of natural cloud seeding over Switzerland from satellite data and sublimation calculations. We use the DARDAR (radar lidar) satellite product between April 2006 and October 2017 to estimate the occurrence frequency of multi-layer cloud situations, where a cirrus cloud at T < −35 ∘C can provide seeds to a lower-lying feeder cloud. These situations are found to occur in 31 % of the observations. Of these, 42 % have a cirrus cloud above another cloud, separated, while in 58 % the cirrus is part of a thicker cloud, with a potential for in-cloud seeding. Vertical distances between the cirrus and the lower-lying cloud are distributed uniformly between 100 m and 10 km. They are found to not vary with topography. Seasonally, winter nights have the most multi-layer cloud occurrences, in 38 % of the measurements. Additionally, in situ and liquid origin cirrus cloud size modes can be identified according to the ice crystal mean effective radius in the DARDAR data. Using sublimation calculations, we show that in a significant number of cases the seeding ice crystals do not sublimate before reaching the lower-lying feeder cloud. Depending on whether bullet rosette, plate-like or spherical crystals were assumed, 10 %, 11 % or 20 % of the crystals, respectively, could provide seeds after sedimenting 2 km. The high occurrence frequency of seeding situations and the survival of the ice crystals indicate that the seeder–feeder process and natural cloud seeding are widespread phenomena over Switzerland. This hints at a large potential for natural cloud seeding to influence cloud properties and thereby the Earth's radiative budget and water cycle, which should be studied globally. Further investigations of the magnitude of the seeding ice crystals' effect on lower-lying clouds are necessary to estimate the contribution of natural cloud seeding to precipitation.

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