Small-scale Structure of Thermodynamic Phase in Arctic Mixed-phase Clouds Observed with Airborne Remote Sensing During the ACLOUD Campaign

Small-scale Structure of Thermodynamic Phase in Arctic Mixed-phase Clouds Observed with Airborne Remote Sensing During the ACLOUD Campaign PDF Author: Elena Ruiz Donoso
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Mixed-Phase Clouds

Mixed-Phase Clouds PDF Author: Constantin Andronache
Publisher: Elsevier
ISBN: 012810550X
Category : Science
Languages : en
Pages : 302

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Book Description
Mixed-Phase Clouds: Observations and Modeling presents advanced research topics on mixed-phase clouds. As the societal impacts of extreme weather and its forecasting grow, there is a continuous need to refine atmospheric observations, techniques and numerical models. Understanding the role of clouds in the atmosphere is increasingly vital for current applications, such as prediction and prevention of aircraft icing, weather modification, and the assessment of the effects of cloud phase partition in climate models. This book provides the essential information needed to address these problems with a focus on current observations, simulations and applications. - Provides in-depth knowledge and simulation of mixed-phase clouds over many regions of Earth, explaining their role in weather and climate - Features current research examples and case studies, including those on advanced research methods from authors with experience in both academia and the industry - Discusses the latest advances in this subject area, providing the reader with access to best practices for remote sensing and numerical modeling

Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds

Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds PDF Author: M. Shupe
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Category :
Languages : en
Pages :

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Recent in situ observations in stratiform clouds suggest that mixed phase regimes, here defined as limited cloud volumes containing both liquid and solid water, are constrained to narrow layers (order 100 m) separating all-liquid and fully glaciated volumes (Hallett and Viddaurre, 2005). The Department of Energy Atmospheric Radiation Measurement Program's (DOE-ARM, Ackerman and Stokes, 2003) North Slope of Alaska (NSA) ARM Climate Research Facility (ACRF) recently started collecting routine measurement of radar Doppler velocity power spectra from the Millimeter Cloud Radar (MMCR). Shupe et al. (2004) showed that Doppler spectra has potential to separate the contributions to the total reflectivity of the liquid and solid water in the radar volume, and thus to investigate further Hallett and Viddaurre's findings. The Mixed-Phase Arctic Cloud Experiment (MPACE) was conducted along the NSA to investigate the properties of Arctic mixed phase clouds (Verlinde et al., 2006). We present surface based remote sensing data from MPACE to discuss the fine-scale structure of the mixed-phase clouds observed during this experiment.

Arctic mixed-phase clouds : Macro- and microphysical insights with a numerical model

Arctic mixed-phase clouds : Macro- and microphysical insights with a numerical model PDF Author: Loewe, Katharina
Publisher: KIT Scientific Publishing
ISBN: 3731506866
Category : Physics
Languages : en
Pages : 174

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This work provides new insights into macro- and microphysical properties of Arctic mixed-phase clouds: first, by comparing semi-idealized large eddy simulations with observations; second, by dissecting the influences of different surface types and boundary layer structures on Arctic mixed- phase clouds; third, by elucidating the dissipation process; and finally by analyzing the main microphysical processes inside Arctic mixed-phase clouds.

Microphysical Properties of Single and Mixed-phase Arctic Clouds Derived from Ground-based AERI Observations

Microphysical Properties of Single and Mixed-phase Arctic Clouds Derived from Ground-based AERI Observations PDF Author: David D. Turner
Publisher:
ISBN:
Category :
Languages : en
Pages : 198

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Arctic Mixed-phase Clouds

Arctic Mixed-phase Clouds PDF Author: Katharina Loewe
Publisher:
ISBN: 9781013281211
Category : Science
Languages : en
Pages : 160

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Book Description
This work provides new insights into macro- and microphysical properties of Arctic mixed-phase clouds: first, by comparing semi-idealized large eddy simulations with observations; second, by dissecting the influences of different surface types and boundary layer structures on Arctic mixed- phase clouds; third, by elucidating the dissipation process; and finally by analyzing the main microphysical processes inside Arctic mixed-phase clouds. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.

Formation of Arctic Mixed-phase Stratocumulus Clouds in Advecting Air Masses

Formation of Arctic Mixed-phase Stratocumulus Clouds in Advecting Air Masses PDF Author: Lucien Simpfendoerfer
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Remote sensing observations across the Arctic indicate that Arctic stratocumuli must form through the cooling of advecting air masses during all seasons, not only in summer as was previously proposed. In this study, radiative transfer calculations and single column model simulations are used to investigate Arctic stratocumuli formation processes and their sensitivities. First, a radiative transfer model and clear-sky radiosonde observations from near Barrow, Alaska, are used to learn about the processes that drive and inhibit cooling within advecting air masses in the Arctic. Next, a single column model simulation is used to investigate how Arctic stratocumuli form when ice precipitation is involved in the formation process. Finally, sets of single column simulations are used to investigate formation processes sensitivities to the availability of moisture, the background static stability, and the ice precipitation rate. Radiative transfer calculations show that Arctic stratocumuli may form through radiative cooling and/or synoptic-scale lifting, and that subsidence is more effective than solar heating in inhibiting cloud formation. The single column model simulations show that ice inhibits the growth of liquid during the formation process and that the outcome of the formation process is extremely sensitive to the environment in which the process occurs. Arctic stratocumuli that form in moist environments with low concentrations of ice forming nuclei are likely to become optically thick and exert a large radiative forcing on the surface. Conversely, Arctic stratocumuli that form in dry environments or in environments with high concentrations of ice forming nuclei are likely to become optically thin or dissipate and exert a small radiative forcing on the surface. Static stability affects the formation process by modifying entrainment rates and therefore modifying the processes sensitivities to the availability of moisture above and below. The results highlight the importance of precipitation-radiative-dynamical interactions in simulating Arctic stratocumuli in larger-scale models.

Microphysical Properties of Single and Mixed-Phase Arctic Clouds Derived from AERI Observations

Microphysical Properties of Single and Mixed-Phase Arctic Clouds Derived from AERI Observations PDF Author:
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ISBN:
Category :
Languages : en
Pages :

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A novel new approach to retrieve cloud microphysical properties from mixed-phase clouds is presented. This algorithm retrieves cloud optical depth, ice fraction, and the effective size of the water and ice particles from ground-based, high-resolution infrared radiance observations. The theoretical basis is that the absorption coefficient of ice is stronger than that of liquid water from 10-13 mm, whereas liquid water is more absorbing than ice from 16-25 um. However, due to strong absorption in the rotational water vapor absorption band, the 16-25 um spectral region becomes opaque for significant water vapor burdens (i.e., for precipitable water vapor amounts over approximately 1 cm). The Arctic is characterized by its dry and cold atmosphere, as well as a preponderance of mixed-phase clouds, and thus this approach is applicable to Arctic clouds. Since this approach uses infrared observations, cloud properties are retrieved at night and during the long polar wintertime period. The analysis of the cloud properties retrieved during a 7 month period during the Surface Heat Budget of the Arctic (SHEBA) experiment demonstrates many interesting features. These results show a dependence of the optical depth on cloud phase, differences in the mode radius of the water droplets in liquid-only and mid-phase clouds, a lack of temperature dependence in the ice fraction for temperatures above 240 K, seasonal trends in the optical depth with the clouds being thinner in winter and becoming more optically thick in the late spring, and a seasonal trend in the effective size of the water droplets in liquid-only and mixed-phase clouds that is most likely related to aerosol concentration.

Light Scattering by Ice Crystals

Light Scattering by Ice Crystals PDF Author: Kuo-Nan Liou
Publisher: Cambridge University Press
ISBN: 0521889162
Category : Science
Languages : en
Pages : 461

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Book Description
This volume outlines the fundamentals and applications of light scattering, absorption and polarization processes involving ice crystals.

Testing Cloud Microphysics Parameterizations and Improving the Representation of the Wegner-Bergeron-Findeisen Process in Mixed-phase Clouds in NCAR CAM5

Testing Cloud Microphysics Parameterizations and Improving the Representation of the Wegner-Bergeron-Findeisen Process in Mixed-phase Clouds in NCAR CAM5 PDF Author: Meng Zhang
Publisher:
ISBN: 9780355325027
Category : Arctic regions
Languages : en
Pages : 52

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Book Description
Mixed-phase clouds are persistently observed in the Arctic and the phase partition of cloud liquid and ice in mixed-phase clouds has important impacts on the surface energy budget and Arctic climate. In this study, we test the NCAR Community Atmosphere Model Version 5 (CAM5) in the single-column and weather forecast modes and evaluate the model performance against observation data obtained during the DOE Atmospheric Radiation Measurement (ARM) Program’s M-PACE field campaign in October 2004 and long-term ground-based multi-sensor measurements. We find that CAM5, like other global climate models, poorly simulates the phase partition in mixed-phase clouds by significantly underestimating the cloud liquid water content. An assumption of the pocket structure in the distribution of cloud liquid and ice based on in situ observations inside mixed-phase clouds has provided a possible solution to improve the model performance by reducing the Wegner-Bergeron-Findeisen (WBF) process rate. In this study, the modification of the WBF process in the CAM5 model has been achieved with applying a stochastic perturbation to the time scale of the WBF process relevant to both ice and snow to account for the heterogeneous mixture of cloud liquid and ice. Our results show that the modification of the WBF process improves the modeled phase partition in mixed-phase clouds. The seasonality of mixed-phase cloud properties is also better captured in the model compared with long-term ground-based remote sensing observations. Furthermore, the phase partitioning is insensitive to the reassignment time step of perturbations.