scholarly journals The Vertical Profile of Liquid and Ice Water Content in Midlatitude Mixed-Phase Altocumulus Clouds

2008 ◽  
Vol 47 (9) ◽  
pp. 2487-2495 ◽  
Author(s):  
Lawrence D. Carey ◽  
Jianguo Niu ◽  
Ping Yang ◽  
J. Adam Kankiewicz ◽  
Vincent E. Larson ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Cloud Microphysics ◽  
Mixed Phase ◽  
The Arctic ◽  
Cloud Base ◽  
Ice Water Content ◽  
Mixed Phase Clouds ◽  
Ice Water ◽  
Water Contents

Abstract The microphysical properties of mixed-phase altocumulus clouds are investigated using in situ airborne measurements acquired during the ninth Cloud Layer Experiment (CLEX-9) over a midlatitude location. Approximately ⅔ of the sampled profiles are supercooled liquid–topped altocumulus clouds characterized by mixed-phase conditions. The coexistence of measurable liquid water droplets and ice crystals begins at or within tens of meters of cloud top and extends down to cloud base. Ice virga is found below cloud base. Peak liquid water contents occur at or near cloud top while peak ice water contents occur in the lower half of the cloud or in virga. The estimation of ice water content from particle size data requires that an assumption be made regarding the particle mass–dimensional relation, resulting in potential error on the order of tens of percent. The highest proportion of liquid is typically found in the coldest (top) part of the cloud profile. This feature of the microphysical structure for the midlatitude mixed-phase altocumulus clouds is similar to that reported for mixed-phase clouds over the Arctic region. The results obtained for limited cases of midlatitude mixed-phase clouds observed during CLEX-9 may have an implication for the study of mixed-phase cloud microphysics, satellite remote sensing applications, and the parameterization of mixed-phase cloud radiative properties in climate models.

scholarly journals Properties of Arctic liquid and mixed phase clouds from ship-borne Cloudnet observations during ACSE 2014

2020 ◽  
Author(s):  
Peggy Achtert ◽  
Ewan J. O'Connor ◽  
Ian M. Brooks ◽  
Georgia Sotiropoulou ◽  
Matthew D. Shupe ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Mixed Phase ◽  
Cloud Base ◽  
Ice Clouds ◽  
Ice Water Content ◽  
Mixed Phase Clouds ◽  
Ice Water ◽  
Cloud Top Temperature

Abstract. This study presents Cloudnet retrievals of Arctic clouds from measurements conducted during a three-month research expedition along the Siberian shelf during summer and autumn 2014. During autumn, we find a strong reduction in the occurrence of liquid clouds and an increase for both mixed-phase and ice clouds at low levels compared to summer. About 80 % of all liquid clouds observed during the research cruise show a liquid water path below the infra-red black body limit of approximately 50 g m−2. The majority of mixed-phase and ice clouds had an ice water path below 20 g m−2. Cloud properties are analysed with respect to cloud-top temperature and boundary layer structure. Changes in these parameters have little effect on the geometric thickness of liquid clouds while mixed-phase clouds during warm-air advection events are generally thinner than when such events were absent. Cloud-top temperatures are very similar for all mixed-phase clouds. However, more cases of lower cloud-top temperature were observed in the absence of warm-air advection. Profiles of liquid and ice water content are normalised with respect to cloud base and height. For liquid water clouds, the liquid water content profile reveals a strong increase with height with a maximum within the upper quarter of the clouds followed by a sharp decrease towards cloud top. Liquid water content is lowest for clouds observed below an inversion during warm-air advection events. Most mixed-phase clouds show a liquid water content profile with a very similar shape to that of liquid clouds but with lower maximum values during warm-air advection. The normalised ice water content profiles in mixed-phase clouds look different from that of liquid water content. They show a wider range in maximum values with lowest ice water content for clouds below an inversion and highest values for clouds above or extending through an inversion. The ice water content profile generally peaks at a height below the peak in the liquid water content profile – usually in the centre of the cloud, sometimes closer to cloud base, likely due to particle sublimation as the crystals fall through the cloud.

scholarly journals Properties of Arctic liquid and mixed-phase clouds from shipborne Cloudnet observations during ACSE 2014

2020 ◽  
Vol 20 (23) ◽  
pp. 14983-15002
Author(s):  
Peggy Achtert ◽  
Ewan J. O'Connor ◽  
Ian M. Brooks ◽  
Georgia Sotiropoulou ◽  
Matthew D. Shupe ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Mixed Phase ◽  
Cloud Base ◽  
Ice Clouds ◽  
Ice Water Content ◽  
Mixed Phase Clouds ◽  
Ice Water ◽  
Cloud Top Temperature

Abstract. This study presents Cloudnet retrievals of Arctic clouds from measurements conducted during a 3-month research expedition along the Siberian shelf during summer and autumn 2014. During autumn, we find a strong reduction in the occurrence of liquid clouds and an increase for both mixed-phase and ice clouds at low levels compared to summer. About 80 % of all liquid clouds observed during the research cruise show a liquid water path below the infrared black body limit of approximately 50 g m−2. The majority of mixed-phase and ice clouds had an ice water path below 20 g m−2. Cloud properties are analysed with respect to cloud-top temperature and boundary layer structure. Changes in these parameters have little effect on the geometric thickness of liquid clouds while mixed-phase clouds during warm-air advection events are generally thinner than when such events were absent. Cloud-top temperatures are very similar for all mixed-phase clouds. However, more cases of lower cloud-top temperature were observed in the absence of warm-air advection. Profiles of liquid and ice water content are normalized with respect to cloud base and height. For liquid water clouds, the liquid water content profile reveals a strong increase with height with a maximum within the upper quarter of the clouds followed by a sharp decrease towards cloud top. Liquid water content is lowest for clouds observed below an inversion during warm-air advection events. Most mixed-phase clouds show a liquid water content profile with a very similar shape to that of liquid clouds but with lower maximum values during events with warm air above the planetary boundary layer. The normalized ice water content profiles in mixed-phase clouds look different from those of liquid water content. They show a wider range in maximum values with the lowest ice water content for clouds below an inversion and the highest values for clouds above or extending through an inversion. The ice water content profile generally peaks at a height below the peak in the liquid water content profile – usually in the centre of the cloud, sometimes closer to cloud base, likely due to particle sublimation as the crystals fall through the cloud.

scholarly journals Measuring ice- and liquid-water properties in mixed-phase cloud layers at the Leipzig Cloudnet station

2016 ◽  
Vol 16 (16) ◽  
pp. 10609-10620 ◽  
Author(s):  
Johannes Bühl ◽  
Patric Seifert ◽  
Alexander Myagkov ◽  
Albert Ansmann
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Mass Flux ◽  
Mixed Phase ◽  
Cloud Base ◽  
Doppler Velocity ◽  
Special Focus ◽  
Data Set ◽  
Ice Water Content ◽  
Ice Water

Abstract. An analysis of the Cloudnet data set collected at Leipzig, Germany, with special focus on mixed-phase layered clouds is presented. We derive liquid- and ice-water content together with vertical motions of ice particles falling through cloud base. The ice mass flux is calculated by combining measurements of ice-water content and particle Doppler velocity. The efficiency of heterogeneous ice formation and its impact on cloud lifetime is estimated for different cloud-top temperatures by relating the ice mass flux and the liquid-water content at cloud top. Cloud radar measurements of polarization and Doppler velocity indicate that ice crystals formed in mixed-phase cloud layers with a geometrical thickness of less than 350 m are mostly pristine when they fall out of the cloud.

scholarly journals Observed aerosol suppression of cloud ice in low-level Arctic mixed-phase clouds

2018 ◽  
Author(s):  
Matthew S. Norgren ◽  
Gijs de Boer ◽  
Matthew D. Shupe
Keyword(s):  
Water Content ◽  
Mixed Phase ◽  
Cloud Base ◽  
Low Level ◽  
Ice Water Content ◽  
Earth’S Climate ◽  
Ice Production ◽  
Mixed Phase Clouds ◽  
Ice Water ◽  
The Impact

Abstract. The interactions that occur between aerosols and a mixed-phase cloud system, and the subsequent alteration of the microphysical state of such clouds, is a problem that has yet to be well constrained. Advancing our understanding of aerosol-ice processes is necessary to determine the impact of natural and anthropogenic emissions on Earth’s climate and to improve our capability to predict future climate states. This paper deals specifically with how aerosols influence ice mass production in low-level Arctic mixed-phase clouds. In this study, a 9-year record of aerosol, cloud and atmospheric state properties is used to quantify aerosol influence on ice production in mixed-phase clouds. It is found that mixed-phase clouds present in a clean aerosol state have higher ice water content by a factor of 1.22 to 1.63 at cloud base than do similar clouds in cases with higher aerosol loading. We additionally analyze radar-derived mean Doppler velocities to better understand the drivers behind this relationship, and conclude that aerosol suppression of ice nucleation, together with reduced riming rates in polluted clouds are likely influences on the observed reductions in ice water content.

In Situ Aircraft Measurements of the Vertical Distribution of Liquid and Ice Water Content in Midlatitude Mixed-Phase Clouds

2013 ◽  
Vol 52 (1) ◽  
pp. 269-279 ◽  
Author(s):  
Yoo-Jeong Noh ◽  
Curtis J. Seaman ◽  
Thomas H. Vonder Haar ◽  
Guosheng Liu
Keyword(s):  
Vertical Distribution ◽  
Water Content ◽  
Liquid Water ◽  
Mixed Phase ◽  
Water Fraction ◽  
Ice Water Content ◽  
Mixed Phase Clouds ◽  
Ice Water ◽  
The Vertical Distribution

AbstractThe vertical distribution of liquid and ice water content and their partitioning is studied using 34 cases of in situ measured microphysical properties in midlatitude mixed-phase clouds, with liquid water path ranging from near zero to ~248 g m−2, total water path ranging from near zero to ~562 g m−2, and cloud-top temperature ranging from −2° to −38°C. The 34 profiles were further divided into three cloud types depending on their vertical extents and altitudes. It is found that both the vertical distribution of liquid water within a cloud and the liquid water fraction (of total condensed water) as a function of temperature or relative position in a cloud layer are cloud-type dependent. In particular, it is found that the partitioning between liquid and ice water for midlevel shallow clouds is relatively independent on the vertical position within the cloud while it clearly depends on cloud mean temperature. For synoptic snow clouds, however, liquid water fraction increases with the decrease of altitude within the cloud. While the liquid water fraction in synoptic clouds also decreases with lowering temperature, its magnitude is only about 50% near 0°C.

scholarly journals Relation between ice and liquid water mass in mixed-phase cloud layers measured with Cloudnet

2016 ◽  
Author(s):  
Johannes Bühl ◽  
Patric Seifert ◽  
Alexander Myagkov ◽  
Albert Ansmann
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Mass Flux ◽  
Mixed Phase ◽  
Ice Formation ◽  
Cloud Base ◽  
Special Focus ◽  
Fall Velocity ◽  
Ice Water Content ◽  
Ice Water

Abstract. An analysis of the Cloudnet dataset collected at Leipzig, Germany, with special focus on mixed-phase layered clouds is presented. We derive liquid and ice water content together with vertical motions of ice particles falling through cloud base. The ice mass flux is calculated by combining measurements of ice water content and particle fall velocity. The efficiency of heterogeneous ice formation and its impact on cloud lifetime is estimated for different cloud-top temperatures by relating the ice mass flux and the liquid water content at cloud top. Cloud radar measurements of polarization and fall velocity yield, that ice crystals formed in cloud layers with a geometrical thickness of less than 350 m are mostly pristine when they fall out of the cloud. It is also found that current and future spaceborne cloud radars might miss a large portion of that primary ice formation, especially for cloud layers with top temperatures warmer than −15 °C.

Evaluation of Microphysics Schemes in Tropical Cyclones using Polarimetric Radar Observations: Convective Precipitation in an Outer Rainband

2021 ◽  
Author(s):  
Dan Wu ◽  
Fuqing Zhang ◽  
Xiaomin Chen ◽  
Alexander Ryzhkov ◽  
Kun Zhao ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Cloud Microphysics ◽  
Convective Precipitation ◽  
Polarimetric Radar ◽  
Error Source ◽  
Ice Water Content ◽  
Ice Water ◽  
Ice Phase

AbstractCloud microphysics significantly impact tropical cyclone precipitation. A prior polarimetric radar observational study by Wu et al. (2018) revealed the ice-phase microphysical processes as the dominant microphysics mechanisms responsible for the heavy precipitation in the outer rainband of Typhoon Nida (2016). To assess the model performance regarding microphysics, three double-moment microphysics schemes (i.e., Thompson, Morrison, and WDM6) are evaluated by performing a set of simulations of the same case. While these simulations capture the outer rainband’s general structure, microphysics in the outer rainbands are strikingly different from the observations. This discrepancy is primarily attributed to different microphysics parameterizations in these schemes, rather than the differences in large-scale environments due to cloud-environment interactions. An interesting finding in this study is that the surface rain rate or liquid water content is inversely proportional to the simulated mean raindrop sizes. The mass-weighted raindrop diameters are overestimated in the Morrison and Thompson schemes and underestimated in the WDM6 scheme, while the former two schemes produce lower liquid water content than WDM6. Compared with the observed ice water content based on a new polarimetric radar retrieval method, the ice water content above the environmental 0 °C level in all simulations is highly underestimated, especially at heights above 12 km MSL where large concentrations of small ice particles are typically prevalent. This finding suggests that the improper treatment of ice-phase processes is potentially an important error source in these microphysics schemes. Another error source identified in the WDM6 scheme is overactive warm-rain processes that produce excessive concentrations of smaller raindrops.

Retrieval and Evaluation of Ice Water Content from the Airborne Wyoming Cloud Radar in Orographic Wintertime Clouds during SNOWNIE

2021 ◽  
Keyword(s):  
Water Content ◽  
Sensitivity Study ◽  
Mixed Phase ◽  
Zero Bias ◽  
Cloud Radar ◽  
Ice Water Content ◽  
The University ◽  
Mixed Phase Clouds ◽  
Ice Water

Abstract The ice water content (IWC) in ice and mixed-phase clouds is retrieved from airborne Wyoming Cloud Radar (WCR) measurements aboard the University of Wyoming King Air (UWKA), which has a suite of integrated in situ IWC, optical array probes (OAP) and remote sensing measurements and provides a unique dataset for this algorithm development and evaluation. A sensitivity study with different idealized ice particle habits shows that the retrieved IWC with aggregate ice particle habit agrees the best with the in situ measurement, especially in ice or ice-dominated mixed-phase clouds with a correlation coefficient (rr) of 0.91 and close-to-zero bias. For mixed-phase clouds with ice fraction ratio less than 0.8, the variances of IWC estimates increase (rr = 0.76) and the retrieved mean IWC is larger than in situ IWC by a factor of 2. This is found to be related to the uncertainty of in situ measurements, the large cloud inhomogeneity, and the retrieval assumption uncertainty. The simulated reflectivity (Ze) and IWC relationships assuming three idealized ice particle habits and measured particle size distributions show that hexagonal columns with the same Ze have a lower IWC than aggregates, whose Ze-IWC relation is more consistent with the observed WCR Ze and in-situ IWC relation in those clouds. The 2DS images also indicate that ice particle habit transition occurs in orographic mixed-phase clouds, hence the retrieved IWC assuming modified Gamma PSD of aggregate particles tends to be biased larger in this kind of clouds.

scholarly journals Controls on phase composition and ice water content in a convection permitting model simulation of a tropical mesoscale convective system

2016 ◽  
Author(s):  
C. N. Franklin ◽  
A. Protat ◽  
D. Leroy ◽  
E. Fontaine
Keyword(s):  
Phase Composition ◽  
Water Content ◽  
Liquid Water ◽  
Mesoscale Convective System ◽  
Convective System ◽  
Particle Sizes ◽  
Mesoscale Convective ◽  
Ice Water Content ◽  
Ice Water ◽  
Water Contents

Abstract. Simulations of tropical convection from an operational numerical weather prediction model are evaluated with the focus on the model's ability to simulate the observed high ice water contents associated with the outflow of deep convection and to investigate the modelled processes that control the phase composition of tropical convective clouds. The intensification and decay of convective strength across the mesoscale convective system lifecycle is simulated well, however, the areas with reflectivities > 30 dBZ are overestimated due to too much rain above the freezing level, stronger updrafts and larger particle sizes in the model. The inclusion of a heterogeneous rain freezing parameterisation and the use of different ice size distributions show better agreement with the observed reflectivity distributions, however, this simulation still produces a broader profile with many high reflectivity outliers demonstrating the greater occurrence of convective cells in the simulations. It is shown that the growth of ice is less dependent on vertical velocity than is liquid water, with the control on liquid water content being the updraft strength due to stronger updrafts having minimal entrainment and higher supersaturations. Larger liquid water contents are produced when cloud droplet number concentrations are increased or when a parameterisation of heterogeneous freezing of rain is included. These changes reduce the efficiency of the warm rain processes in the model generating greater supercooled liquid water contents. The control on ice water content in the model is the ice sizes and available liquid water, with the larger ice particles growing more efficiently via accretion and riming. Limiting or excluding graupel produces larger ice water contents for warmer temperatures due to the greater ice mass contained in slow falling snow particles. This results in longer in-cloud residence times and more efficient removal of liquid water. It is demon strated that entrainment in the mixed-phase regions of convective updrafts is most sensitive to the turbulence formulation in the model. Greater mixing of environmental air into cloudy updrafts in the region of -30 to 0 degrees Celsius produces more detrainment at these temperatures and the generation of a larger stratiform area. Above these levels in the purely ice region of the updrafts, the entrainment and buoyancy of air parcels is controlled by the ice particle sizes, demonstrating the importance of the microphysical processes on the convective dynamics.

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