Improvements of an Ice-Phase Microphysics Parameterization for Use in Numerical Simulations of Tropical Convection

1995 ◽  
Vol 34 (1) ◽  
pp. 281-287 ◽  
Author(s):  
Steven K. Krueger ◽  
Qiang Fu ◽  
K. N. Liou ◽  
Hung-Neng S. Chin
Keyword(s):  
Numerical Simulations ◽  
Numerical Models ◽  
Radiation Budget ◽  
Cloud Formation ◽  
Squall Line ◽  
Ice Water Content ◽  
Microphysical Processes ◽  
Cloud Ice ◽  
Ice Water ◽  
Ice Phase

Abstract It is important to properly simulate the extent and ice water content of tropical anvil clouds in numerical models that explicitly include cloud formation because of the significant effects that these clouds have on the radiation budget. For this reason, a commonly used bulk ice-phase microphysics parameterization was modified to more realistically simulate some of the microphysical processes that occur in tropical anvil clouds. Cloud ice growth by the Bergeron process and the associated formation of snow were revised. The characteristics of graupel were also modified in accord with a previous study. Numerical simulations of a tropical squall line demonstrate that the amount of cloud ice and the extent of anvil clouds are increased to more realistic values by the first two changes.

scholarly journals Partitioning Ice Water Content from Retrievals and Its Application in Model Comparison

2018 ◽  
Vol 75 (4) ◽  
pp. 1105-1120 ◽  
Author(s):  
Min Deng ◽  
Gerald G. Mace ◽  
Zhien Wang ◽  
J.-L. F. Li ◽  
Yali Luo
Keyword(s):  
Particle Size ◽  
Water Content ◽  
Model Comparison ◽  
Partition Ratio ◽  
Ice Water Content ◽  
Mode Transitions ◽  
Cloud Ice ◽  
The Tropics ◽  
Ice Water ◽  
Ice Phase

Abstract Retrieved bulk microphysics from remote sensing observations is a composite of ice, snow, and graupel in the three-species ice-phase bulk microphysics parameterization. In this study, density thresholds are used to partition the retrieved ice particle size distribution (PSD) into small, median, and large particle size modes from millimeter cloud radar (MMCR) observations in the tropics and global CloudSat and CALIPSO ice cloud property product (2C-ICE) observations. It shows that the small mode can contribute to more than 60% of the total ice water content (IWC) above 12 km (colder than 220 K). Below that, dominant small mode transitions to dominant median mode. The large mode contributes to less than 10%–20% at all height levels. The PSD assumption in retrieval may cause about 10% error in the IWC partition ratio. The lidar-only region in 2C-ICE is dominated by the small mode, while the median mode dominates the radar-only region. For the three-species ice-phase bulk microphysics parameterizations, the cloud ice mass mainly consists of the small mode. But snow and graupel in the models are not equivalent to the median and large modes in the observations, respectively. Therefore, they need to be repartitioned with rebuilt PSDs from the model assumptions using the same partition technique as the observations. The repartitioned IWCs in each mode from different ice species need to be added together and then compared with the corresponding mode from observations.

scholarly journals Evolution of DARDAR-CLOUD ice cloud cloud retrieval: new parameters and impacts on the retrieved microphysical properties

2018 ◽  
Author(s):  
Quitterie Cazenave ◽  
Marie Ceccaldi ◽  
Julien Delanoë ◽  
Jacques Pelon ◽  
Silke Groß ◽  
...  
Keyword(s):  
Water Content ◽  
Ice Clouds ◽  
Ice Cloud ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
Ice Water Content ◽  
Microphysical Processes ◽  
Pm 10 ◽  
Cloud Ice ◽  
Ice Water

Abstract. In this paper we present the latest refinements brought to the DARDAR-CLOUD product, which contains ice cloud microphysical properties retrieved from the cloud radar and lidar measurements from the A-Train mission. Based on a large dataset of in-situ ice cloud measurements collected during several campaigns performed between 2000 and 2007 in different regions of the globe, the parameterizations used in the microphysical model of the algorithm were assessed and refined to 5 better fit the measurements, keeping the same formalism as proposed in DARDAR basis papers. It is shown that these changes can affect the ice water content retrievals by up to 50 %, with, globally, a reduction of the ice water content and ice water path. In parallel, the retrieved effective radii increase between 5 % and 40 %. The largest differences are found for the warmest temperatures (between −20 °C and 0 °C) in regions where the cloud microphysical processes are more complex and where the retrieval is almost exclusively based on radar-only measurements. In regions where lidar measurements are available, the lidar 10 ratio retrieved for ice clouds is shown to be well constrained by lidar-radar combination or molecular signal detected below thin semi-transparent cirrus. Using this information, the parameterization of the lidar ratio was refined and the new retrieval equals on average 35 sr ± 10 sr in the temperature range between −60 °C and −20 °C.

Ice-Phase Precipitation

2017 ◽  
Vol 58 ◽  
pp. 6.1-6.36 ◽  
Author(s):  
I. Gultepe ◽  
A. J. Heymsfield ◽  
P. R. Field ◽  
D. Axisa
Keyword(s):  
Collection Efficiency ◽  
Numerical Models ◽  
Mass Density ◽  
Three Dimensional ◽  
Phase Precipitation ◽  
Microphysical Parameters ◽  
Mass Size ◽  
Ice Water ◽  
Ice Phase

AbstractIce-phase precipitation occurs at Earth’s surface and may include various types of pristine crystals, rimed crystals, freezing droplets, secondary crystals, aggregates, graupel, hail, or combinations of any of these. Formation of ice-phase precipitation is directly related to environmental and cloud meteorological parameters that include available moisture, temperature, and three-dimensional wind speed and turbulence, as well as processes related to nucleation, cooling rate, and microphysics. Cloud microphysical parameters in the numerical models are resolved based on various processes such as nucleation, mixing, collision and coalescence, accretion, riming, secondary ice particle generation, turbulence, and cooling processes. These processes are usually parameterized based on assumed particle size distributions and ice crystal microphysical parameters such as mass, size, and number and mass density. Microphysical algorithms in the numerical models are developed based on their need for applications. Observations of ice-phase precipitation are performed using in situ and remote sensing platforms, including radars and satellite-based systems. Because of the low density of snow particles with small ice water content, their measurements and predictions at the surface can include large uncertainties. Wind and turbulence affecting collection efficiency of the sensors, calibration issues, and sensitivity of ground-based in situ observations of snow are important challenges to assessing the snow precipitation. This chapter’s goals are to provide an overview for accurately measuring and predicting ice-phase precipitation. The processes within and below cloud that affect falling snow, as well as the known sources of error that affect understanding and prediction of these processes, are discussed.

scholarly journals Observations and modelling of microphysical variability, aggregation and sedimentation in tropical anvil cirrus outflow regions

2012 ◽  
Vol 12 (14) ◽  
pp. 6609-6628 ◽  
Author(s):  
M. W. Gallagher ◽  
P. J. Connolly ◽  
I. Crawford ◽  
A. Heymsfield ◽  
K. N. Bower ◽  
...  
Keyword(s):  
Electric Fields ◽  
Numerical Models ◽  
Average Particle Size ◽  
Average Particle ◽  
Ice Crystal ◽  
Crystal Aggregation ◽  
Ice Water Content ◽  
Differential Sedimentation ◽  
High Electric Fields ◽  
Ice Water

Abstract. Aircraft measurements of the microphysics of a tropical convective anvil (at temperatures ~−60 °C) forming above the Hector storm, over the Tiwi Islands, Northern Australia, have been conducted with a view to determining ice crystal aggregation efficiencies from in situ measurements. The observed microphysics have been compared to an explicit bin-microphysical model of the anvil region, which includes crystal growth by vapour diffusion and aggregation and the process of differential sedimentation. It has been found in flights made using straight and level runs perpendicular to the storm that the number of ice crystals initially decreased with distance from the storm as aggregation took place resulting in larger crystals, followed by their loss from the cloud layer due to sedimentation. The net result was that the mass (i.e. Ice Water Content) in the anvil Ci cloud decreased, but also that the average particle size (weighted by number) remained relatively constant along the length of the anvil outflow. Comparisons with the explicit microphysics model showed that the changes in the shapes of the ice crystal spectra as a function of distance from the storm could be explained by the model if the aggregation efficiency was set to values of Eagg~0.5 and higher. This result is supported by recent literature on aggregation efficiencies for complex ice particles and suggests that either the mechanism of particle interlocking is important to the aggregation process, or that other effects are occuring, such as enhancement of ice-aggregation by high electric fields that arise as a consequence of charge separation within the storm. It is noteworthy that this value of the ice crystal aggregation efficiency is much larger than values used in cloud resolving models at these temperatures, which typically use E~0.0016. These results are important to understanding how cold clouds evolve in time and for the treatment of the evolution of tropical Ci in numerical models.

Infrared limb sounding of cirrus clouds: state of knowledge, recent progress, and future prospects

2020 ◽  
Author(s):  
Reinhold Spang ◽  
Irene Bartolome ◽  
Jörn Ungermann ◽  
Sabine Griessbach ◽  
Lars Hoffmann ◽  
...  
Keyword(s):  
Cirrus Clouds ◽  
Radiation Budget ◽  
Current Status ◽  
Radiation Balance ◽  
Particle Parameter ◽  
Future Space ◽  
Lidar Measurements ◽  
Tropopause Region ◽  
Ice Water Content ◽  
Ice Water

<p>Cirrus clouds are the highest altitude clouds in the troposphere and play an important role in the climate system. They can either have a cooling or heating effect in radiation balance around of the planet, depending on which altitude and temperature they appear. Despite the importance of this type of clouds for the radiation budget there are still big gaps of knowledge regarding their micro and macro physical properties (e.g. particle sizes, ice water content, occurrence and coverage at the upper troposphere and lower stratosphere), especially for optically very thin cirrus in the tropopause region, which are difficult to detect even for active lidar measurements. <span>Due to the long path length through the atmosphere and good vertical resolution passive infrared limb measurements are especially well suited to observe this type of clouds. The presentation will highlight the current status in infrared limb sounding and corresponding particle parameter retrievals with respect to recent and future space and airborne sensors (e.g. CRISTA, MIPAS, </span><span>and IR limb-imaging instruments</span><span>). </span></p>

scholarly journals Changes in the shape of cloud ice water content vertical structure due to aerosol variations

2016 ◽  
Vol 16 (10) ◽  
pp. 6091-6105 ◽  
Author(s):  
Steven T. Massie ◽  
Julien Delanoë ◽  
Charles G. Bardeen ◽  
Jonathan H. Jiang ◽  
Lei Huang
Keyword(s):  
Water Content ◽  
Vertical Structure ◽  
Distribution Functions ◽  
Ozone Monitoring Instrument ◽  
Modis Aod ◽  
Ice Water Content ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Cloud Ice ◽  
Ice Water ◽  
Derivatives Of

Abstract. Changes in the shape of cloud ice water content (IWC) vertical structure due to variations in Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depths (AODs), Ozone Monitoring Instrument (OMI) absorptive aerosol optical depths (AAODs), and Microwave Limb Sounder (MLS) CO (an absorptive aerosol proxy) at 215 hPa are calculated in the Tropics during 2007–2010 based upon an analysis of DARDAR IWC profiles for deep convective clouds. DARDAR profiles are a joint retrieval of CloudSat-CALIPSO data. Analysis is performed for 12 separate regions over land and ocean, and carried out applying MODIS AOD fields that attempt to correct for 3-D cloud adjacency effects. The 3-D cloud adjacency effects have a small impact upon our particular calculations of aerosol–cloud indirect effects. IWC profiles are averaged for three AOD bins individually for the 12 regions. The IWC average profiles are also normalized to unity at 5 km altitude in order to study changes in the shape of the average IWC profiles as AOD increases. Derivatives of the IWC average profiles, and derivatives of the IWC shape profiles, in percent change per 0.1 change in MODIS AOD units, are calculated separately for each region. Means of altitude-specific probability distribution functions, which include both ocean and land IWC shape regional derivatives, are modest, near 5 %, and positive to the 2σ level between 11 and 15 km altitude. Similar analyses are carried out for three AAOD and three CO bins. On average, the vertical profiles of the means of the derivatives based upon the profile shapes over land and ocean are smaller for the profiles binned according to AAOD and CO values, than for the MODIS AODs, which include both scattering and absorptive aerosol. This difference in character supports the assertion that absorptive aerosol can inhibit cloud development.

scholarly journals Microphysical Processes Producing High Ice Water Contents (HIWCs) in Tropical Convective Clouds during the HAIC-HIWC Field Campaign: Evaluation of Simulations Using Bulk Microphysical Schemes

2020 ◽  
Author(s):  
Yongjie Huang ◽  
Wei Wu ◽  
Greg M. McFarquhar ◽  
Xuguang Wang ◽  
Hugh Morrison ◽  
...  
Keyword(s):  
Water Content ◽  
Ice Crystals ◽  
Field Campaign ◽  
Campaign Evaluation ◽  
Convective Clouds ◽  
Ice Water Content ◽  
Microphysical Processes ◽  
The Tropics ◽  
Ice Water ◽  
Water Contents

Abstract. Regions with high ice water content (HIWC), composed of mainly small ice crystals, frequently occur over convective clouds in the tropics. Such regions can have median mass diameters (MMDs)

scholarly journals Changes in the shape of cloud ice water content vertical structure due to aerosol variations

2016 ◽  
Author(s):  
Steven T. Massie ◽  
Julien Delanoe ◽  
Charles G. Bardeen
Keyword(s):  
Water Content ◽  
Vertical Structure ◽  
Distribution Functions ◽  
Convective Clouds ◽  
Modis Aod ◽  
Ice Water Content ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Cloud Ice ◽  
Ice Water ◽  
Derivatives Of

Abstract. Changes in the shape of cloud ice water content vertical structure due to aerosol variations are calculated in the Tropics during 2007–2010 based upon an analysis of DARDAR ice water content (IWC) profiles for deep convective clouds. DARDAR profiles are a joint retrieval of CloudSat-CALIPSO data. Our analysis is performed for 12 separate regions over land and ocean, and carried out applying Moderate-Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) fields that attempt to correct for 3D cloud adjacency effects. The 3D cloud adjacency effects have a small impact upon our calculations of aerosol-cloud indirect effects. IWC profiles are averaged for three AOD bins individually for the 12 regions. The IWC average profiles are also normalized to unity at 5 km altitude in order to study changes in the shape of the average IWC profiles as AOD increases. Derivatives of the IWC average profiles, and derivatives of the IWC shape profiles, in percent change per 0.1 change in MODIS AOD units, are calculated separately for each region. Means of altitude-specific probability distribution functions, which include both ocean and land IWC shape regional derivatives, are modest, near 5 %, and positive to the 2σ level between 11 and 15 km altitude.

scholarly journals Retrieving microphysical properties of concurrent pristine ice and snow using polarimetric radar observations

2021 ◽  
Author(s):  
Nicholas J. Kedzuf ◽  
J. Christine Chiu ◽  
Venkatachalam Chandrasekar ◽  
Sounak Biswas ◽  
Shashank S. Joshil ◽  
...  
Keyword(s):  
Water Content ◽  
Number Concentration ◽  
Radiation Budget ◽  
Radar Signal ◽  
Polarimetric Radar ◽  
Radar Observations ◽  
Microphysical Properties ◽  
Uncertainty Estimates ◽  
Ice Water Content ◽  
Ice Water

Abstract. Ice and mixed phase clouds play a key role in our climate system, because of their strong controls on global precipitation and radiation budget. Their microphysical properties have been characterized commonly by polarimetric radar measurements. However, there remains a lack of robust estimates of microphysical properties of concurrent pristine ice and aggregates, because larger snow aggregates often dominate the radar signal and mask contributions of smaller pristine ice crystals. This paper presents a new method that separates the scattering signals of pristine ice embedded in snow aggregates in scanning polarimetric radar observations and retrieves their respective abundances and sizes for the first time. This method, dubbed ENCORE-ice, is built on an iterative stochastic ensemble retrieval framework. It provides number concentration, ice water content, and effective mean diameter of pristine ice and snow aggregates with uncertainty estimates. Evaluations against synthetic observations show that the overall retrieval biases in the combined total microphysical properties are within 5 %, and that the errors with respect to the truth are well within the retrieval uncertainty. The partitioning between pristine ice and snow aggregates also agrees well with the truth. Additional evaluations against in-situ cloud probe measurements from a recent campaign for a stratiform cloud system are promising. Our median retrievals have a bias of 98 % in total ice number concentration and 44 % in total ice water content. This performance is generally better than the retrieval from empirical relationships. The ability to separate signals of different ice species and to provide their quantitative microphysical properties will open many research opportunities, such as secondary ice production studies and model evaluations for ice microphysical processes.

scholarly journals MLS and CALIOP Cloud Ice Measurements in the Upper Troposphere: A Constraint from Microwave on Cloud Microphysics

2014 ◽  
Vol 53 (1) ◽  
pp. 157-165 ◽  
Author(s):  
Dong L. Wu ◽  
Alyn Lambert ◽  
William G. Read ◽  
Patrick Eriksson ◽  
Jie Gong
Keyword(s):  
Empirical Relationship ◽  
Cloud Microphysics ◽  
Orthogonal Polarization ◽  
Microwave Frequencies ◽  
Upper Troposphere ◽  
Ice Water Content ◽  
Microwave Techniques ◽  
Cloud Ice ◽  
Ice Water ◽  
532 Nm

AbstractThis study examines the consistency and microphysics assumptions among satellite ice water content (IWC) retrievals in the upper troposphere with collocated A-Train radiances from Microwave Limb Sounder (MLS) and lidar backscatters from Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP). For the cases in which IWC values are small (<10 mg m−3), the cloud ice retrievals are constrained by both MLS 240- and 640-GHz radiances and CALIOP 532-nm backscatter β532. From the observed relationships between MLS cloud-induced radiance Tcir and the CALIOP backscatter integrated γ532 along the MLS line of sight, an empirical linear relation between cloud ice and the lidar backscatter is found: IWC/β532 = 0.58 ± 0.11. This lidar cloud ice relation is required to satisfy the cloud ice emission signals simultaneously observed at microwave frequencies, in which ice permittivity is relatively well known. This empirical relationship also produces IWC values that agree well with the CALIOP, version 3.0, retrieval at values <10 mg m−3. Because the microphysics assumption is critical in satellite cloud ice retrievals, the agreement found in the IWC–β532 relationships increase fidelity of the assumptions used by the lidar and microwave techniques for upper-tropospheric clouds.

Sign in / Sign up

Export Citation Format

Share Document