scholarly journals Characteristics of vertical air motion in isolated convective clouds

2016 ◽  
Vol 16 (15) ◽  
pp. 10159-10173 ◽  
Author(s):  
Jing Yang ◽  
Zhien Wang ◽  
Andrew J. Heymsfield ◽  
Jeffrey R. French
Keyword(s):  
Vertical Velocity ◽  
Mass Flux ◽  
Convective Precipitation ◽  
Small Scale ◽  
High Plains ◽  
Air Mass ◽  
Convective Clouds ◽  
Field Campaigns ◽  
Air Motion

Abstract. The vertical velocity and air mass flux in isolated convective clouds are statistically analyzed using aircraft in situ data collected from three field campaigns: High-Plains Cumulus (HiCu) conducted over the midlatitude High Plains, COnvective Precipitation Experiment (COPE) conducted in a midlatitude coastal area, and Ice in Clouds Experiment-Tropical (ICE-T) conducted over a tropical ocean. The results show that small-scale updrafts and downdrafts (<  500 m in diameter) are frequently observed in the three field campaigns, and they make important contributions to the total air mass flux. The probability density functions (PDFs) and profiles of the observed vertical velocity are provided. The PDFs are exponentially distributed. The updrafts generally strengthen with height. Relatively strong updrafts (>  20 m s−1) were sampled in COPE and ICE-T. The observed downdrafts are stronger in HiCu and COPE than in ICE-T. The PDFs of the air mass flux are exponentially distributed as well. The observed maximum air mass flux in updrafts is of the order 104 kg m−1 s−1. The observed air mass flux in the downdrafts is typically a few times smaller in magnitude than that in the updrafts. Since this study only deals with isolated convective clouds, and there are many limitations and sampling issues in aircraft in situ measurements, more observations are needed to better explore the vertical air motion in convective clouds.

scholarly journals Characteristics of Vertical Air Motion in Convective Clouds

2016 ◽  
Author(s):  
Jing Yang ◽  
Zhien Wang ◽  
Andrew J. Heymsfield ◽  
Jeffrey R. French
Keyword(s):  
Vertical Velocity ◽  
Mass Flux ◽  
Convective Precipitation ◽  
Small Scale ◽  
High Plains ◽  
Tropical Ocean ◽  
Air Mass ◽  
Convective Clouds ◽  
In Situ Data ◽  
Field Campaigns

Abstract. The vertical velocity and air mass flux in convective clouds are statistically analyzed using aircraft in-situ data collected from three field campaigns: High-Plains Cumulus (HiCu) conducted over the mid-latitude High Plains, COnvective Precipitation Experiment (COPE) conducted in a mid-latitude coastal area, and Ice in Clouds Experiment-Tropical (ICE-T), conducted over a tropical ocean. This study yields the following results. (1) Small-scale updrafts and downdrafts (< 500 m in diameter) are frequently observed in the three field campaigns, and they make important contributions to the total air mass flux. (2) The probability density functions (PDFs) of the vertical velocity are exponentially distributed. For updrafts, the PDFs of the vertical velocity are broader in ICE-T and COPE than in HiCu; for downdrafts, the PDFs of the vertical velocity are broader in HiCu and COPE than in ICE-T. (3) Vertical velocity profiles show that updrafts are stronger in ICE-T and COPE than in HiCu, and downdrafts are stronger in HiCu and COPE than in ICE-T. (4) The PDFs of the air mass flux are exponentially distributed as well. The maximum air mass flux in updrafts is of the order 104 kg m−1 s−1. The air mass flux in the downdrafts is typically a few times smaller in magnitude than that in the updrafts.

scholarly journals Modeling the ascent of sounding balloons: derivation of the vertical air motion

2011 ◽  
Vol 4 (3) ◽  
pp. 3965-4012
Author(s):  
A. Gallice ◽  
F. G. Wienhold ◽  
C. R. Hoyle ◽  
F. Immler ◽  
T. Peter
Keyword(s):  
Drag Coefficient ◽  
Vertical Velocity ◽  
Heat Diffusion ◽  
Small Scale ◽  
Reference Curve ◽  
Heat Diffusion Equation ◽  
Ascent Rate ◽  
Potential Applications ◽  
Radial Heat ◽  
Air Motion

Abstract. A new model to describe the ascent of sounding balloons in the troposphere and lower stratosphere (up to ~30–35 km altitude) is presented. Contrary to previous models, detailed account is taken of both the variation of the drag coefficient with altitude and the heat imbalance between the balloon and the atmosphere. To compensate for the lack of data on the drag coefficient of sounding balloons, a reference curve for the relationship between drag coefficient and Reynolds number is derived from a dataset of flights launched during the Lindenberg Upper Air Methods Intercomparisons (LUAMI) campaign. The transfer of heat from the surrounding air into the balloon is accounted for by solving the radial heat diffusion equation inside the balloon. The potential applications of the model include the forecast of the trajectory of sounding balloons, which can be used to increase the accuracy of the match technique, and the derivation of the air vertical velocity. The latter is obtained by subtracting the ascent rate of the balloon in still air calculated by the model from the actual ascent rate. This technique is shown to provide an approximation for the vertical air motion with an uncertainty error of 0.5 m s−1 in the troposphere and 0.2 m s−1 in the stratosphere. An example of extraction of the air vertical velocity is provided in this paper. We show that the air vertical velocities derived from the balloon soundings in this paper are in general agreement with small-scale atmospheric velocity fluctuations related to gravity waves, mechanical turbulence, or other small-scale air motions measured during the SUCCESS campaign (Subsonic Aircraft: Contrail and Cloud Effects Special Study) in the orographically unperturbed mid-latitude middle troposphere.

scholarly journals Airborne measurements and large-eddy simulations of small-scale Gravity Waves at the tropopause inversion layer over Scandinavia

2020 ◽  
Author(s):  
Sonja Gisinger ◽  
Johannes Wagner ◽  
Benjamin Witschas
Keyword(s):  
Velocity Field ◽  
Gravity Waves ◽  
Vertical Velocity ◽  
Inversion Layer ◽  
Small Scale ◽  
Airborne Measurements ◽  
In Situ Data ◽  
Lidar Measurements ◽  
Wind Lidar

Abstract. Coordinated airborne measurements were performed by the two research aircraft DLR Falcon and HALO (High Altitude and Long Range Aircraft) in Scandinavia during the GW-LCYCLE~II (Investigation of the life cycle of gravity waves) campaign in 2016 to investigate gravity wave processes in the upper troposphere and lower stratosphere (UTLS) region. A mountain wave event was probed over Southern Scandinavia on 28 January 2016. The collected dataset constitutes a valuable combination of in-situ measurements and horizontal- and altitude-resolved wind lidar and water vapour lidar measurements. In-situ data at different flight altitudes and downward pointing Doppler wind lidar measurements show pronounced changes of the horizontal scales in the vertical velocity field and of the leg-averaged momentum fluxes (MF) in the UTLS region. The vertical velocity field was dominated by small horizontal scales with a decrease from around 20 km to

scholarly journals Modeling the ascent of sounding balloons: derivation of the vertical air motion

2011 ◽  
Vol 4 (10) ◽  
pp. 2235-2253 ◽  
Author(s):  
A. Gallice ◽  
F. G. Wienhold ◽  
C. R. Hoyle ◽  
F. Immler ◽  
T. Peter
Keyword(s):  
Solar Radiation ◽  
Drag Coefficient ◽  
Vertical Velocity ◽  
Heat Diffusion ◽  
Small Scale ◽  
Reference Curve ◽  
Heat Diffusion Equation ◽  
Ascent Rate ◽  
Potential Applications ◽  
Air Motion

Abstract. A new model to describe the ascent of sounding balloons in the troposphere and lower stratosphere (up to ∼30–35 km altitude) is presented. Contrary to previous models, detailed account is taken of both the variation of the drag coefficient with altitude and the heat imbalance between the balloon and the atmosphere. To compensate for the lack of data on the drag coefficient of sounding balloons, a reference curve for the relationship between drag coefficient and Reynolds number is derived from a dataset of flights launched during the Lindenberg Upper Air Methods Intercomparisons (LUAMI) campaign. The transfer of heat from the surrounding air into the balloon is accounted for by solving the radial heat diffusion equation inside the balloon. In its present state, the model does not account for solar radiation, i.e. it is only able to describe the ascent of balloons during the night. It could however be adapted to also represent daytime soundings, with solar radiation modeled as a diffusive process. The potential applications of the model include the forecast of the trajectory of sounding balloons, which can be used to increase the accuracy of the match technique, and the derivation of the air vertical velocity. The latter is obtained by subtracting the ascent rate of the balloon in still air calculated by the model from the actual ascent rate. This technique is shown to provide an approximation for the vertical air motion with an uncertainty error of 0.5 m s−1 in the troposphere and 0.2 m s−1 in the stratosphere. An example of extraction of the air vertical velocity is provided in this paper. We show that the air vertical velocities derived from the balloon soundings in this paper are in general agreement with small-scale atmospheric velocity fluctuations related to gravity waves, mechanical turbulence, or other small-scale air motions measured during the SUCCESS campaign (Subsonic Aircraft: Contrail and Cloud Effects Special Study) in the orographically unperturbed mid-latitude middle troposphere.

Microphysical Processes Evident in Aerosol Forcing of Tropical Deep Convective Clouds

2013 ◽  
Vol 70 (2) ◽  
pp. 430-446 ◽  
Author(s):  
Rachel L. Storer ◽  
Susan C. van den Heever
Keyword(s):  
Vertical Velocity ◽  
Large Scale ◽  
Extreme Values ◽  
Cloud Microphysics ◽  
Aerosol Concentration ◽  
Convective Precipitation ◽  
Latent Heating ◽  
Convective Clouds ◽  
Budget Analysis ◽  
Deep Convective Clouds

Abstract This study investigates the effects of aerosols on tropical deep convective clouds (DCCs). A series of large-scale, two-dimensional cloud-resolving model simulations was completed, differing only in the concentration of aerosols available to act as cloud condensation nuclei (CCN). Polluted simulations contained more DCCs, wider storms, higher cloud tops, and more convective precipitation domainwide. Differences in warm cloud microphysics were largely consistent with the first and second aerosol indirect effects. The average surface precipitation produced in each DCC column decreased with increasing aerosol concentration. A detailed microphysical budget analysis showed that the reduction in collision and coalescence largely dominated the trend in average precipitation. The production of rain from ice, though it also decreased, became a more important contribution to precipitation as the aerosol concentration increased. The DCCs in polluted simulations contained more frequent extreme values of vertical velocity, but the average updraft speed decreased with increasing aerosols in DCCs above 6 km. An examination of the buoyancy term of the vertical velocity equation demonstrates that the drag associated with condensate loading is an important factor in determining the average updraft strength. The largest contributions to latent heating in DCCs were cloud nucleation and vapor deposition onto water and ice, but changes in latent heating were, on average, an order of magnitude smaller than those in the condensate loading term. The average updraft speed was largely affected by increased drag from condensate loading in more mature updrafts, while early storm updrafts experienced convective invigoration from increased latent heating.

IN-SITU AND GRACE-BASED GROUNDWATER OBSERVATIONS: SIMILARITIES, DISCREPANCIES, AND EVALUATION IN THE HIGH PLAINS AQUIFER IN KANSAS

2017 ◽  
Author(s):  
Andrea E. Brookfield ◽  
◽  
Mary C. Hill ◽  
Matthew Rodell ◽  
Bryant Loomis ◽  
...  
Keyword(s):  
High Plains ◽  
High Plains Aquifer

scholarly journals Upscaling THM modeling from small-scale to full-scale in-situ experiments in the Callovo-Oxfordian claystone

2021 ◽  
Vol 144 ◽  
pp. 104582
Author(s):  
D.M. Seyedi ◽  
C. Plúa ◽  
M. Vitel ◽  
G. Armand ◽  
J. Rutqvist ◽  
...  
Keyword(s):  
Full Scale ◽  
Small Scale ◽  
In Situ Experiments

Evolution of the Vertical Mass Flux and Diagnosed Net Lateral Mixing in Isolated Convective Clouds

1996 ◽  
Vol 124 (12) ◽  
pp. 2764-2784 ◽  
Author(s):  
Gary M. Barnes ◽  
James C. Fankhauser ◽  
Wesley D. Browning
Keyword(s):  
Mass Flux ◽  
Convective Clouds ◽  
Lateral Mixing

Coupled Thermo-Hydro-Geochemical Models of Engineered Barrier Systems: The Febex Project

2000 ◽  
Vol 663 ◽  
Author(s):  
J. Samper ◽  
R. Juncosa ◽  
V. Navarro ◽  
J. Delgado ◽  
L. Montenegro ◽  
...  
Keyword(s):  
Large Scale ◽  
Reference Model ◽  
Numerical Models ◽  
Full Scale ◽  
Small Scale ◽  
Model Parameters ◽  
In Situ Test ◽  
Wide Range ◽  
Engineered Barrier

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

Study of Thermal Activity in The Mixing Layer During First Generated Single Cloud by Using Combined Observation From Boundary Layer Radar, Doppler Lidar and Time Lapse Camera 

2021 ◽  
Author(s):  
Ginaldi Ari Nugroho ◽  
Kosei Yamaguchi ◽  
Eiichi Nakakita ◽  
Masayuki K. Yamamoto ◽  
Seiji Kawamura ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Time Series ◽  
Atmospheric Boundary Layer ◽  
Vertical Velocity ◽  
Time Lapse ◽  
Small Scale ◽  
Thermal Activity ◽  
Doppler Lidar ◽  
Cumulus Cloud ◽  
Scale Perturbation

&lt;p&gt;Detailed observation of small scale perturbation in the atmospheric boundary layer during the first generated cumulus cloud are conducted. Our target is to study this small scale perturbation, especially related to the thermal activity at the first generated cumulus cloud. The observation is performed during the daytime on August 17, 2018, and September 03, 2018. Location is focused in the urban area of Kobe, Japan. High-resolution instruments such as Boundary Layer Radar, Doppler Lidar, and Time Lapse camera are used in this observation. Boundary Layer Radar, and Doppler Lidar are used for clear air observation. Meanwhile Time Lapse Camera are used for cloud existence observation. The atmospheric boundary layer structure is analyzed based on vertical velocity profile, variance, skewness, and estimated atmospheric boundary layer height. Wavelet are used to observe more of the period of the thermal activity. Furthermore, time correlation between vertical velocity time series from height 0.3 to 2 km and image pixel of generated cloud time series are also discussed in this study.&lt;/p&gt;

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