scholarly journals The Role of Unresolved Clouds on Short-Range Global Horizontal Irradiance Predictability

2016 ◽  
Vol 144 (9) ◽  
pp. 3099-3107 ◽  
Author(s):  
Pedro A. Jiménez ◽  
Stefano Alessandrini ◽  
Sue Ellen Haupt ◽  
Aijun Deng ◽  
Branko Kosovic ◽  
...  
Keyword(s):  
Model Uncertainty ◽  
Short Range ◽  
Solar Model ◽  
Cumulus Clouds ◽  
High Quality ◽  
Ensemble Simulations ◽  
Shallow Cumulus ◽  
Implicit Model ◽  
Radiative Impacts

The shortwave radiative impacts of unresolved cumulus clouds are investigated using 6-h ensemble simulations performed with the WRF-Solar Model and high-quality observations over the contiguous United States for a 1-yr period. The ensembles use the stochastic kinetic energy backscatter scheme (SKEBS) to account for implicit model uncertainty. Results indicate that parameterizing the radiative effects of both deep and shallow cumulus clouds is necessary to largely reduce (55%) a systematic overprediction of the global horizontal irradiance. Accounting for the model’s effective resolution is necessary to mitigate the underdispersive nature of the ensemble and provide meaningful quantification of the short-range prediction uncertainties.

Large-scale vertical motion and its influence on cloudiness

2020 ◽  
Author(s):  
Geet George ◽  
Bjorn Stevens ◽  
Sandrine Bony ◽  
Marcus Klingebiel
Keyword(s):  
Large Scale ◽  
Vertical Motion ◽  
Cumulus Clouds ◽  
Shallow Cumulus ◽  
Integrated Water Vapour ◽  
Thermodynamics And Dynamics ◽  
Lifting Condensation Level ◽  
The Impact ◽  
First Time

<p>This study uses measurements from the <em>Elucidating the Role of Clouds-Circulation Coupling in Climate</em>, EUREC<sup>4</sup>A and the second <em>Next-Generation Aircraft Remote Sensing for Validation</em>, NARVAL2 campaigns to investigate the influence of large-scale environmental conditions on cloudiness. For the first time, these campaigns provide divergence measurements, making it possible to explore the impact of large-scale vertical motions on clouds. We attempt to explain the cloudiness through the varying thermodynamics and dynamics in the different environments.  For most of the NARVAL2 case-studies, cloudiness is poorly related to thermodynamical factors such as sea-surface temperature and lower tropospheric stability. Factors such as integrated water vapour and pressure velocity (ω) at 500 hPa and 700 hPa can be used to distinguish between actively convecting and suppressed regions, but they are not useful in determining the variation in cloudiness among suppressed cases. We find that ω in the boundary layer (up to ∼2 km) has a more direct control on the low-level cloudiness in these regions, than that in the upper layers. We use a simplistic method to show that ω at the lifting condensation level can be used to determine the cloud cover of shallow cumulus clouds. Thus, we argue that cloud schemes in models should not rely only on thermodynamical information, but also on dynamical predictors.</p>

The Role of Cloud Size and Environmental Moisture in Shallow Cumulus Precipitation

2020 ◽  
Vol 59 (3) ◽  
pp. 535-550
Author(s):  
Kevin M. Smalley ◽  
Anita D. Rapp
Keyword(s):  
Satellite Observations ◽  
Cumulus Cloud ◽  
Power Law Distribution ◽  
Cumulus Clouds ◽  
Active Sensors ◽  
Cloud Models ◽  
Shallow Cumulus ◽  
Shallow Clouds ◽  
Entrainment Mixing

AbstractCloud models show that precipitation is more likely to occur in larger shallow clouds and/or in an environment with more moisture, in part as a result of decreasing the impacts of entrainment mixing on the updrafts. However, the role of cloud size in shallow cloud precipitation onset from global satellite observations has mostly been examined with precipitation proxies from imagers and has not been systematically examined in active sensors, primarily because of sensitivity limitations of previous spaceborne active instruments. Here we use the more sensitive CloudSat/CALIPSO observations to identify and characterize the properties of individual contiguous shallow cumulus cloud objects. The objects are conditionally sampled by cloud-top height to determine the changes in precipitation likelihood with increasing cloud size and column water vapor. On average, raining shallow cumulus clouds are typically taller by a factor of 2 and have a greater horizontal extent than their nonraining counterparts. Results show that for a fixed cloud-top height the likelihood of precipitation increases with increasing cloud size and generally follows a double power-law distribution. This suggests that the smallest cloud objects are able to grow freely within the boundary layer but the largest cloud objects are limited by environmental moisture. This is supported by our results showing that, for a fixed cloud-top height and cloud size, the precipitation likelihood also increases as environmental moisture increases. These results are consistent with the hypothesis that larger clouds occurring in a wetter environment may be better able to protect their updrafts from entrainment effects, increasing their chances of raining.

scholarly journals Direct Numerical Simulation of Evaporative Cooling at the Lateral Boundary of Shallow Cumulus Clouds

2013 ◽  
Vol 70 (7) ◽  
pp. 2088-2102 ◽  
Author(s):  
Dick Abma ◽  
Thijs Heus ◽  
Juan Pedro Mellado
Keyword(s):  
Scaling Laws ◽  
Evaporative Cooling ◽  
Lateral Boundary ◽  
Cumulus Clouds ◽  
Buoyancy Reversal ◽  
Shallow Cumulus ◽  
Large Eddy ◽  
Thermodynamic Conditions

Abstract This study investigates the dynamics of the subsiding shell at the lateral boundary of cumulus clouds, focusing on the role of evaporative cooling. Since the size of this shell is well below what large-eddy simulations can resolve, the authors have performed direct numerical simulations of an idealized subsiding shell. The system develops a self-similar, Reynolds number–independent flow that allows for the determination of explicit scaling laws relating the characteristic length, time, and velocity scales of the shell. It is found that the shell width grows quadratically in time, linearly with the traveled distance. The magnitude of these growth rates shows that evaporative cooling, in its most idealized form, is capable of producing a fast-growing shell with numbers that are consistent with observations of the subsiding shell around real shallow cumulus clouds: for typical thermodynamic conditions in cumulus clouds, a velocity on the order of 1 m s−1 and a thickness on the order of 10 m are established in about 2 min. This fits well within the typical cloud lifetime, suggesting that this idealization is an adequate framework for the analysis of relevant aspects in the subsiding shell associated with buoyancy reversal. It also indicates that the scaling laws derived here can be used to estimate the potential strength of a subsiding shell and the mean lateral entrainment associated with it, once an estimate of the local thermodynamical state of the cloud boundary is provided. It is shown that the dominant parameter of this system is the saturation buoyancy, whereas the effect of the saturation mixing fraction is minor.

scholarly journals Deployment of the C-band radar Poldirad on Barbados during EUREC<sup>4</sup>A

2021 ◽  
Vol 13 (12) ◽  
pp. 5899-5914
Author(s):  
Martin Hagen ◽  
Florian Ewald ◽  
Silke Groß ◽  
Lothar Oswald ◽  
David A. Farrell ◽  
...  
Keyword(s):  
Rain Rate ◽  
Radar Signal ◽  
Trade Wind ◽  
Cumulus Clouds ◽  
Radar Images ◽  
Shallow Cumulus ◽  
Maximum Range ◽  
Research Aircraft ◽  
Radar Measurements

Abstract. The German polarimetric C-band weather radar Poldirad (Polarization Diversity Radar) was deployed for the international field campaign EUREC4A (Elucidating the role of clouds–circulation coupling in climate) on the island of Barbados where it was operated from February until August 2020. Focus of the installation was monitoring clouds and precipitation in the trade wind region east of Barbados. Different scanning modes were used with a temporal sequence of 5 min and a maximum range of 375 km. In addition to built-in quality control performed by the radar signal processor, it was found that the copoloar correlation coefficient ρHV can be used to remove contamination of radar products by sea clutter. Radar images were available in real time for all campaign participants and aboard research aircraft. Examples of mesoscale precipitation patterns, rain rate accumulation, diurnal cycle, and vertical distribution are given to show the potential of the radar measurements for further studies on the life cycle of precipitating shallow cumulus clouds and other related aspects. Poldirad data from the EUREC4A campaign are available on the EUREC4A AERIS database: https://doi.org/10.25326/218 (Hagen et al., 2021a) for raw data and https://doi.org/10.25326/217 (Hagen et al., 2021b) for gridded data.

scholarly journals The role of the gamma function shape parameter in determining differences between condensation rates in bin and bulk microphysics schemes

2017 ◽  
Vol 17 (7) ◽  
pp. 4599-4609 ◽  
Author(s):  
Adele L. Igel ◽  
Susan C. van den Heever
Keyword(s):  
Droplet Size ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Cumulus Clouds ◽  
Model Framework ◽  
Secondary Importance ◽  
Shallow Cumulus ◽  
Cloud Droplet Size Distribution ◽  
Droplet Size Distributions

Abstract. The condensation and evaporation rates predicted by bin and bulk microphysics schemes in the same model framework are compared in a statistical way using simulations of non-precipitating shallow cumulus clouds. Despite other fundamental disparities between the bin and bulk condensation parameterizations, the differences in condensation rates are predominantly explained by accounting for the width of the cloud droplet size distributions simulated by the bin scheme. While the bin scheme does not always predict a cloud droplet size distribution that is well represented by a gamma distribution function (which is assumed by bulk schemes), this fact appears to be of secondary importance for explaining why the two schemes predict different condensation and evaporation rates. The width of the cloud droplet size is not well constrained by observations, and thus it is difficult to know how to appropriately specify it in bulk microphysics schemes. However, this study shows that enhancing our observations of this width and its behavior in clouds is important for accurately predicting condensation and evaporation rates.

scholarly journals Deployment of the C-band radar Poldirad on Barbados during EUREC<sup>4</sup>A

2021 ◽  
Author(s):  
Martin Hagen ◽  
Florian Ewald ◽  
Silke Groß ◽  
Lothar Oswald ◽  
David A. Farrell ◽  
...  
Keyword(s):  
Rain Rate ◽  
Radar Signal ◽  
Trade Wind ◽  
Cumulus Clouds ◽  
Radar Images ◽  
Shallow Cumulus ◽  
Maximum Range ◽  
Research Aircraft ◽  
Radar Measurements

Abstract. The German polarimetric C-band weather radar Poldirad (Polarization Diversity Radar) was deployed for the international field campaign EUREC4A (ElUcidating the RolE of Cloud-Circulation Coupling in ClimAte) on the island of Barbados. Poldirad was operated on Barbados from February until August 2020. Focus of the installation was monitoring clouds and precipitation in the trade wind region east of Barbados. Different scanning modes were used with a temporal sequence of 5 minutes and a maximum range of 375 km. In addition to built-in quality control performed by the radar signal processor, it was found that the copoloar correlation coefficient ρHV can be used to remove contamination of radar products by sea clutter. Radar images were available in real-time for all campaign participants and onboard of research aircraft. Examples of mesoscale precipitation patterns, rain rate accumulation, diurnal cycle, and vertical distribution are given to show the potential of the radar measurements for further studies on the life cycle of precipitating shallow cumulus clouds and other related aspects. Poldirad data from the EUREC4A campaign are available on the EUREC4A AERIS database: https://doi.org/10.25326/218 (Hagen et al., 2021a) for raw data and https://doi.org/10.25326/217 (Hagen et al., 2021b) for gridded data.

Making Movies and Community of Talent

2019 ◽  
Vol 10 (11) ◽  
pp. 1057-1064
Author(s):  
Katsuhiko Hirasawa ◽  
Keyword(s):  
Shop Floor ◽  
High Quality ◽  
Democratic Leadership ◽  
Staff Members

Staff members at a movie company Daiei, known for presumably the world’s best film technology, continued to produce movies for several months even after the company went bankrupt. It was because they desired to make outstanding films. A director can create a high-quality film by combining the skills and ideas of such staff. Akira Kurosawa named the group that could produce excellent works the “Community of Talents”. By using research on a community as a clue, this paper aims to highlight how the “Community of Talents” is organized. First I point out that a “Community of Talents” is formulated primarily by the labor of the staff based on Kumazawa’s “Community on the Shop Floor”. The paper subsequently refers to research by Heinrich Nicklish, a representative researcher on the study of community in Germany, in an attempt to verify that the community is a group of people established on functions. Lastly, the paper explores Guido Fisher’s research to reveal the role of democratic leadership centered on the director who transforms the objectified staff in the organization into an independently-minded presence and help them prove their abilities. The paper continues to emphasize the significance of leadership in the formation of the “Community of Talents”.

When Do Auditors Use Specialists' Work to Improve Problem Representations of and Judgments about Complex Estimates?

2017 ◽  
Vol 93 (4) ◽  
pp. 177-202 ◽  
Author(s):  
Emily E. Griffith
Keyword(s):  
Pattern Recognition ◽  
Situational Factors ◽  
Situational Factor ◽  
High Quality ◽  
Quality Audit ◽  
Domain Specific ◽  
Epistemic Motivation ◽  
Specific Expertise ◽  
Problem Representations

ABSTRACT Auditors are more likely to identify misstatements in complex estimates if they recognize problematic patterns among an estimate's underlying assumptions. Rich problem representations aid pattern recognition, but auditors likely have difficulty developing them given auditors' limited domain-specific expertise in this area. In two experiments, I predict and find that a relational cue in a specialist's work highlighting aggressive assumptions improves auditors' problem representations and subsequent judgments about estimates. However, this improvement only occurs when a situational factor (e.g., risk) increases auditors' epistemic motivation to incorporate the cue into their problem representations. These results suggest that auditors do not always respond to cues in specialists' work. More generally, this study highlights the role of situational factors in increasing auditors' epistemic motivation to develop rich problem representations, which contribute to high-quality audit judgments in this and other domains where pattern recognition is important.

scholarly journals A Cloud Microphysics Parameterization for Shallow Cumulus Clouds Based on Lagrangian Cloud Model Simulations

2018 ◽  
Vol 75 (11) ◽  
pp. 4031-4047 ◽  
Author(s):  
Yign Noh ◽  
Donggun Oh ◽  
Fabian Hoffmann ◽  
Siegfried Raasch
Keyword(s):  
Cloud Model ◽  
Cloud Microphysics ◽  
Heaviside Function ◽  
Mixing Ratio ◽  
Cumulus Clouds ◽  
Cloud Droplets ◽  
Shallow Cumulus ◽  
Initial Stage ◽  
Accretion Rates ◽  
The Moment

Abstract Cloud microphysics parameterizations for shallow cumulus clouds are analyzed based on Lagrangian cloud model (LCM) data, focusing on autoconversion and accretion. The autoconversion and accretion rates, A and C, respectively, are calculated directly by capturing the moment of the conversion of individual Lagrangian droplets from cloud droplets to raindrops, and it results in the reproduction of the formulas of A and C for the first time. Comparison with various parameterizations reveals the closest agreement with Tripoli and Cotton, such as and , where and are the mixing ratio and the number concentration of cloud droplets, is the mixing ratio of raindrops, is the threshold volume radius, and H is the Heaviside function. Furthermore, it is found that increases linearly with the dissipation rate and the standard deviation of radius and that decreases rapidly with while disappearing at &gt; 3.5 μm. The LCM also reveals that and increase with time during the period of autoconversion, which helps to suppress the early precipitation by reducing A with smaller and larger in the initial stage. Finally, is found to be affected by the accumulated collisional growth, which determines the drop size distribution.

Sign in / Sign up

Export Citation Format

Share Document