scholarly journals Properties of Tropical and Midlatitude Ice Cloud Particle Ensembles. Part II: Applications for Mesoscale and Climate Models

2003 ◽  
Vol 60 (21) ◽  
pp. 2592-2611 ◽  
Author(s):  
Andrew J. Heymsfield
Keyword(s):  
Climate Models ◽  
Cloud Particle ◽  
Ice Cloud

scholarly journals Influence of convection and aerosol pollution on ice cloud particle effective radius

2010 ◽  
Vol 10 (10) ◽  
pp. 23091-23108 ◽  
Author(s):  
J. H. Jiang ◽  
H. Su ◽  
C. Zhai ◽  
S. T. Massie ◽  
M. R. Schoeberl ◽  
...  
Keyword(s):  
Climate Models ◽  
Analytical Formula ◽  
Effective Radius ◽  
Cloud Particle ◽  
Ice Cloud ◽  
Geographical Regions ◽  
Aerosol Pollution ◽  
Ice Water Content ◽  
Aerosol Effects ◽  
Ice Water

Abstract. Satellite observations show that ice cloud effective radius (re) increases with ice water content (IWC) but decreases with aerosol optical thickness (AOT). Using least-squares fitting to the observed data, we obtain an analytical formula to describe the variations of re with IWC and AOT for several regions with distinct characteristics of re-IWC-AOT relationships. As IWC directly relates to convective strength and AOT represents aerosol loading, our empirical formula provides a means to quantify the relative roles of dynamics and aerosols in controlling re in different geographical regions, and to establish a framework for parameterization of aerosol effects on re in climate models.

Impacts of Ice Cloud Particle Size Uncertainty on Radiation, and Precipitation and Climate Sensitivity and the Significance of Future Satellite-Based Constraints

2020 ◽  
Author(s):  
Hui Su ◽  
Yuan Wang ◽  
Jonathan Jiang ◽  
Feng Xu ◽  
Yuk Yung
Keyword(s):  
Particle Size ◽  
Climate Sensitivity ◽  
Climate Models ◽  
Global Scale ◽  
Radiative Effect ◽  
Cloud Particle ◽  
Ice Cloud ◽  
Cloud Radiative Effect ◽  
Fall Speed ◽  
Radiation Scheme

<p>Ice cloud particle size is important to determining ice cloud radiative effect and precipitating rate. However, there is a lack of accurate ice particle effective radius (R<sub>ei</sub>) observation on the global scale and the parameterization of R<sub>ei</sub> in climate models is poorly constrained. We conduct a modeling study to assess the sensitivity of climate simulations to R<sub>ei</sub>. Perturbations to R<sub>ei</sub> are represented in ice fall speed parameterization and radiation scheme, respectively, in NCAR CESM1 model with a slab ocean configuration. We show that an increase in ice fall speed due to a larger R<sub>ei</sub> results in a longwave cooling dominating over a shortwave warming, a global mean surface temperature decrease, and precipitation suppression. Similar longwave and shortwave cloud radiative effect changes occur when R<sub>ei</sub> is perturbed in the radiation scheme. Perturbing falling snow particle size (R<sub>es</sub>) results in much smaller changes in the climate responses. We further show that varying R<sub>ei</sub> and R<sub>es</sub> by 50% to 200% relative to the control experiment can cause climate sensitivity to differ by +12.3% to −6.2%. A future mission under design with combined multi-frequency microwave radiometers and cloud radar can reduce the uncertainty ranges of R<sub>ei</sub> and R<sub>es</sub> from a factor of 2 to ±25%, which would help reducing the climate sensitivity uncertainty pertaining to ice cloud particle size by approximately 60%.</p><p> </p>

scholarly journals Arctic ice clouds over northern Sweden: microphysical properties studied with the Balloon-borne Ice Cloud particle Imager B-ICI

2018 ◽  
Vol 18 (23) ◽  
pp. 17371-17386 ◽  
Author(s):  
Veronika Wolf ◽  
Thomas Kuhn ◽  
Mathias Milz ◽  
Peter Voelger ◽  
Martina Krämer ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Shape ◽  
Climate Models ◽  
Number Concentration ◽  
Cirrus Clouds ◽  
The Arctic ◽  
Cloud Particle ◽  
Ice Cloud ◽  
Almost All

Abstract. Ice particle and cloud properties such as particle size, particle shape and number concentration influence the net radiation effect of cirrus clouds. Measurements of these features are of great interest for the improvement of weather and climate models, especially for the Arctic region. In this study, balloon-borne in situ measurements of Arctic cirrus clouds have been analysed for the first time with respect to their origin. Eight cirrus cloud measurements have been carried out in Kiruna (68∘ N), Sweden, using the Balloon-borne Ice Cloud particle Imager (B-ICI). Ice particle diameters between 10 and 1200 µm have been found and the shape could be recognized from 20 µm upwards. Great variability in particle size and shape is observed. This cannot simply be explained by local environmental conditions. However, if sorted by cirrus origin, wind and weather conditions, the observed differences can be assessed. Number concentrations between 3 and 400 L−1 have been measured, but the number concentration has reached values above 100 L−1 only for two cases. These two cirrus clouds are of in situ origin and have been associated with waves. For all other measurements, the maximum ice particle concentration is below 50 L−1 and for one in situ origin cirrus case only 3 L−1. In the case of in situ origin clouds, the particles are all smaller than 350 µm diameter. The PSDs for liquid origin clouds are much broader with particle sizes between 10 and 1200 µm. Furthermore, it is striking that in the case of in situ origin clouds almost all particles are compact (61 %) or irregular (25 %) when examining the particle shape. In liquid origin clouds, on the other hand, most particles are irregular (48 %), rosettes (25 %) or columnar (14 %). There are hardly any plates in cirrus regardless of their origin. It is also noticeable that in the case of liquid origin clouds the rosettes and columnar particles are almost all hollow.

scholarly journals Influence of convection and aerosol pollution on ice cloud particle effective radius

2011 ◽  
Vol 11 (2) ◽  
pp. 457-463 ◽  
Author(s):  
J. H. Jiang ◽  
H. Su ◽  
C. Zhai ◽  
S. T. Massie ◽  
M. R. Schoeberl ◽  
...  
Keyword(s):  
Climate Models ◽  
Analytical Formula ◽  
Effective Radius ◽  
Cloud Particle ◽  
Ice Cloud ◽  
Geographical Regions ◽  
Aerosol Pollution ◽  
Ice Water Content ◽  
Aerosol Effects ◽  
Ice Water

Abstract. Satellite observations show that ice cloud effective radius (re) increases with ice water content (IWC) but decreases with aerosol optical thickness (AOT). Using least-squares fitting to the observed data, we obtain an analytical formula to describe the variations of re with IWC and AOT for several regions with distinct characteristics of re-IWC-AOT relationships. As IWC directly relates to convective strength and AOT represents aerosol loading, our empirical formula provides a means to quantify the relative roles of dynamics and aerosols in controlling re in different geographical regions, and to establish a framework for parameterization of aerosol effects on re in climate models.

scholarly journals Footprint-scale cloud type mixtures and their impacts on Atmospheric Infrared Sounder cloud property retrievals

2019 ◽  
Vol 12 (8) ◽  
pp. 4361-4377 ◽  
Author(s):  
Alexandre Guillaume ◽  
Brian H. Kahn ◽  
Eric J. Fetzer ◽  
Qing Yue ◽  
Gerald J. Manipon ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Deep Convection ◽  
Cloud Microphysics ◽  
Specific Humidity ◽  
Phase Detection ◽  
Cloud Type ◽  
Atmospheric Infrared Sounder ◽  
Cloud Particle ◽  
Cloud Property ◽  
Ice Cloud

Abstract. A method is described to classify cloud mixtures of cloud top types, termed cloud scenes, using cloud type classification derived from the CloudSat radar (2B-CLDCLASS). The scale dependence of the cloud scenes is quantified. For spatial scales at 45 km (15 km), only 18 (10) out of 256 possible cloud scenes account for 90 % of all observations and contain one, two, or three cloud types. The number of possible cloud scenes is shown to depend on spatial scale with a maximum number of 210 out of 256 possible scenes at a scale of 105 km and fewer cloud scenes at smaller and larger scales. The cloud scenes are used to assess the characteristics of spatially collocated Atmospheric Infrared Sounder (AIRS) thermodynamic-phase and ice cloud property retrievals within scenes of varying cloud type complexity. The likelihood of ice and liquid-phase detection strongly depends on the CloudSat-identified cloud scene type collocated with the AIRS footprint. Cloud scenes primarily consisting of cirrus, nimbostratus, altostratus, and deep convection are dominated by ice-phase detection, while stratocumulus, cumulus, and altocumulus are dominated by liquid- and undetermined-phase detection. Ice cloud particle size and optical thickness are largest for cloud scenes containing deep convection and cumulus and are smallest for cirrus. Cloud scenes with multiple cloud types have small reductions in information content and slightly higher residuals of observed and modeled radiance compared to cloud scenes with single cloud types. These results will help advance the development of temperature, specific humidity, and cloud property retrievals from hyperspectral infrared sounders that include cloud microphysics in forward radiative transfer models.

scholarly journals Remote sensing of ice crystal asymmetry parameter using multi-directional polarization measurements – Part 2: Application to the Research Scanning Polarimeter

2012 ◽  
Vol 12 (12) ◽  
pp. 32063-32107
Author(s):  
B. van Diedenhoven ◽  
B. Cairns ◽  
A. M. Fridlind ◽  
A. S. Ackerman ◽  
T. J. Garrett
Keyword(s):  
Asymmetry Parameter ◽  
Climate Models ◽  
Continuous Selection ◽  
Ice Crystals ◽  
Shortwave Radiation ◽  
Convective Clouds ◽  
Ice Cloud ◽  
Aspect Ratios ◽  
The Asymmetry ◽  
Asymmetry Parameters

Abstract. A new method to retrieve ice cloud asymmetry parameters from multi-directional polarized reflectance measurements is applied to measurements of the airborne Research Scanning Polarimeter (RSP) obtained during the CRYSTAL-FACE campaign in 2002. The method assumes individual hexagonal ice columns and plates serve as proxies for more complex shapes and aggregates. The closest fit is searched in a look-up table of simulated polarized reflectances computed for cloud layers that contain individual, randomly oriented hexagonal columns and plates with a virtually continuous selection of aspect ratios and distortion. The asymmetry parameter, aspect ratio and distortion of the hexagonal particle that leads to the best fit with the measurements are considered the retrieved values. Two cases of thick convective clouds and two cases of thinner anvil cloud layers are analyzed. Median asymmetry parameters retrieved by the RSP range from 0.76 to 0.78, and are generally smaller that those currently assumed in most climate models and satellite retrievals. In all cases the measurements indicate roughened ice crystals, which is consistent with previous findings. Retrieved aspect ratios in three of the cases range from 0.9 to 1.6, indicating compact particles dominate the cloud-top shortwave radiation. Retrievals for the remaining case indicate plate-like ice crystals with aspect ratios around 0.3. The RSP retrievals are qualitatively consistent with the CPI images obtained in the same cloud layers. Retrieved asymmetry parameters are compared to those determined in situ by the Cloud Integrating Nephelometer (CIN). For two cases, the median values of asymmetry parameter retrieved by CIN and RSP agree within 0.01, while for the two other cases RSP asymmetry parameters are about 0.03–0.05 greater than those obtained by the CIN. Part of this bias might be explained by vertical variation of the asymmetry parameter.

scholarly journals Properties of ice cloud over Beijing from surface Ka-band radar observations during 2014–2017

2020 ◽  
Vol 20 (22) ◽  
pp. 14377-14392
Author(s):  
Juan Huo ◽  
Yufang Tian ◽  
Xue Wu ◽  
Congzheng Han ◽  
Bo Liu ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Climate Models ◽  
Winter Monsoon ◽  
Global Climate Models ◽  
Cirrus Clouds ◽  
Ice Clouds ◽  
Ice Cloud ◽  
Cloud Clusters ◽  
The Mean

Abstract. The physical properties and radiative role of ice clouds remain one of the uncertainties in the Earth–atmosphere system. In this study, we present a detailed analysis of ice cloud properties based on 4 years of surface millimeter-wavelength radar measurements in Beijing, China, where the summer monsoon from the ocean and the winter monsoon from the continent prevail alternately, resulting in various ice clouds. More than 6300 ice cloud clusters were studied to quantify the properties of ice clouds, such as the height, optical depth and horizontal extent, which can serve as a reference for parameterization and characterization in global climate models. In addition, comparison between ice cloud clusters formed under the summer monsoon and the winter monsoon indicates the different formation and evolution mechanisms of cirrus clouds. Statistically, temperatures of more than 95 % of ice radar bins are below −15 ∘C and more than 80 % of ice clouds are above 7 km. The dependence of the radar reflectivity of ice particles on height and temperature was also observed in this study, indicating that the reflectivity of ice bins increases (decreases) as the temperature (height) increases. In addition, it is found that there is a strong linear relationship between the mean reflectivity and the ice cloud depth. Due to various synoptic circumstances, the ice clouds in summer are warmer, higher and thicker, with larger reflectivity than that in winter; in particular, the mean cloud-top height of ice clouds in summer is 2.2 km higher than that in winter. Our analysis indicates that in spring, in situ-origin cirrus clouds are more common than liquid-origin cirrus clouds, while in summer liquid-origin cirrus clouds are more frequent; in autumn and winter, most cirrus clouds are of in situ origin.

scholarly journals Importance of including ammonium sulfate ((NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>) aerosols for ice cloud parameterization in GCMs

2010 ◽  
Vol 28 (2) ◽  
pp. 621-631 ◽  
Author(s):  
P. S. Bhattacharjee ◽  
Y. C. Sud ◽  
X. Liu ◽  
G. K. Walker ◽  
R. Yang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ammonium Sulfate ◽  
Circulation Model ◽  
Substantial Improvement ◽  
The Other ◽  
Global Circulation Model ◽  
Cloud Particle ◽  
Ice Cloud ◽  
Cloud Parameterization ◽  
Aerosol Cloud Interactions

Abstract. A common deficiency of many cloud-physics parameterizations including the NASA's microphysics of clouds with aerosol-cloud interactions (hereafter called McRAS-AC) is that they simulate lesser (larger) than the observed ice cloud particle number (size). A single column model (SCM) of McRAS-AC physics of the GEOS4 Global Circulation Model (GCM) together with an adiabatic parcel model (APM) for ice-cloud nucleation (IN) of aerosols were used to systematically examine the influence of introducing ammonium sulfate (NH4)2SO4 aerosols in McRAS-AC and its influence on the optical properties of both liquid and ice clouds. First an (NH4)2SO4 parameterization was included in the APM to assess its effect on clouds vis-à-vis that of the other aerosols. Subsequently, several evaluation tests were conducted over the ARM Southern Great Plain (SGP) and thirteen other locations (sorted into pristine and polluted conditions) distributed over marine and continental sites with the SCM. The statistics of the simulated cloud climatology were evaluated against the available ground and satellite data. The results showed that inclusion of (NH4)2SO4 into McRAS-AC of the SCM made a remarkable improvement in the simulated effective radius of ice cloud particulates. However, the corresponding ice-cloud optical thickness increased even more than the observed. This can be caused by lack of horizontal cloud advection not performed in the SCM. Adjusting the other tunable parameters such as precipitation efficiency can mitigate this deficiency. Inclusion of ice cloud particle splintering invoked empirically further reduced simulation biases. Overall, these changes make a substantial improvement in simulated cloud optical properties and cloud distribution particularly over the Intertropical Convergence Zone (ITCZ) in the GCM.

On the retrieval of ice cloud particle shapes from POLDER measurements

2006 ◽  
Vol 101 (3) ◽  
pp. 435-447 ◽  
Author(s):  
Wenbo Sun ◽  
Norman G. Loeb ◽  
Ping Yang
Keyword(s):  
Cloud Particle ◽  
Ice Cloud ◽  
Particle Shapes
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