Some Aspects of the Optical Properties of Ice Clouds

Liou, Kuo‐Nan

doi:10.1016/b978-0-12-350720-4.50012-0

Cited by 3 publications

(1 citation statement)

References 83 publications

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“…As this can lead to rapid formation of hydrometeors with significant fall velocities through the Wegener-Bergeron-Findeisen process (Findeisen, 1938;Storelvmo & Tan, 2015), most precipitation on Earth, in particular over continents, stems from clouds with mixed phase, or ice tops (Mülmenstädt et al, 2015). Furthermore, the radiative effects of liquid and ice clouds differ due to changes in hydrometeor size distributions and scattering properties (Liou, 1981;Petty, 2004) as well as differences in the typical cloud altitude, thickness, and lifetime. Thus, liquid, mixed-phase, and ice clouds have distinct effects on the surface and top-of-the-atmosphere radiative budgets (Cesana & Storelvmo, 2017;Matus & L'Ecuyer, 2017).…”

Section: Introductionmentioning

confidence: 99%

Cloud Top Phase Distributions of Simulated Deep Convective Clouds

2018

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Space‐based observations of the thermodynamic cloud phase are frequently used for the analysis of aerosol indirect effects and other regional and temporal trends of cloud properties; yet they are mostly limited to the cloud top layers. This study addresses the information content in cloud top phase distributions of deep convective clouds during their growing stage. A cloud‐resolving model with grid spacings of 300 m and lower is used in two different setups, simulating idealized and semiidealized isolated convective clouds of different strengths. It is found that the cloud top phase distribution is systematically shifted to higher temperatures compared to the in‐cloud phase distribution due to lower vertical velocities and a resultingly stronger Wegener‐Bergeron‐Findeisen process at the cloud top. Sensitivity studies show that heterogeneous freezing can modify the cloud top glaciation temperature (where the ice pixel fraction reaches 50%) and ice multiplication via rime splintering is visible in an early ice onset at temperatures around −10°C. However, if the analyses are repeated with a coarsened horizontal resolution (above 1 km, similar to many satellite data sets), a significant part of this signal is lost, which limits the detectability of these microphysical fingerprints in the observable cloud top phase distribution. In addition, variation in the cloud dynamics also impacts the cloud phase distribution but cannot be quantified easily.

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Section: Introductionmentioning

confidence: 99%

Cloud Top Phase Distributions of Simulated Deep Convective Clouds

2018

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Preliminary laboratory studies of the optical scattering properties of the crystal clouds

et al. 1998

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Abstract. Ice crystal clouds have an in¯uence on the radiative budget of the earth; however, the exact size and nature of this in¯uence has yet to be determined. A laboratory cloud chamber experiment has been set up to provide data on the optical scattering behaviour of ice crystals at a visible wavelength in order to gain information which can be used in climate models concerning the radiative characteristics of cirrus clouds. A PMS grey-scale probe is used to monitor simultaneously the cloud microphysical properties in order to correlate these closely with the observed radiative properties. Preliminary results show that ice crystals scatter considerably more at 90°than do water droplets, and that the halo eects are visible in a laboratorygenerated cloud when the ice crystal concentration is suciently small to prevent masking from multiple scattering.

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Vertical 2-μm Heterodyne Differential Absorption Lidar Measurements of Mean CO2 Mixing Ratio in the Troposphere

Gibert

Flamant

Cuesta

et al. 2008

Journal of Atmospheric and Oceanic Technology

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Vertical mean CO 2 mixing ratio measurements are reported in the atmospheric boundary layer (ABL) and in the lower free troposphere (FT), using a 2-m heterodyne differential absorption lidar (HDIAL). The mean CO 2 mixing ratio in the ABL is determined using 1) aerosol backscatter signal and a mean derivative of the increasing optical depth as a function of altitude and 2) optical depth measurements from cloud target returns. For a 1-km vertical long path in the ABL, 2% measurement precision with a time resolution of 30 min is demonstrated for the retrieved mean CO 2 absorption. Spectroscopic calculations are reported in details using new spectroscopic data in the 2-m domain and the outputs of the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5). Then, using both aerosols in the ABL and midaltitude dense clouds in the free troposphere, preliminary HDIAL measurements of mean CO 2 mixing ratio in the free troposphere are also presented. The 2-m HDIAL vertical measurements are compared to ground-based and airborne in situ CO 2 mixing ratio measurements and discussed with the atmospheric synoptic conditions.

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Some Aspects of the Optical Properties of Ice Clouds

Cited by 3 publications

References 83 publications

Cloud Top Phase Distributions of Simulated Deep Convective Clouds

Cloud Top Phase Distributions of Simulated Deep Convective Clouds

Preliminary laboratory studies of the optical scattering properties of the crystal clouds

Vertical 2-μm Heterodyne Differential Absorption Lidar Measurements of Mean CO2 Mixing Ratio in the Troposphere

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