scholarly journals Numerically Simulated Electrification and Lightning of the 29 June 2000 STEPS Supercell Storm

2006 ◽  
Vol 134 (10) ◽  
pp. 2734-2757 ◽  
Author(s):  
Kristin M. Kuhlman ◽  
Conrad L. Ziegler ◽  
Edward R. Mansell ◽  
Donald R. MacGorman ◽  
Jerry M. Straka
Keyword(s):  
Mass Flux ◽  
Cloud Model ◽  
Three Dimensional ◽  
Cloud Water ◽  
Severe Thunderstorm ◽  
Charge Structure ◽  
Flash Rate ◽  
Supercell Storm ◽  
Mapping Array ◽  
Cloud To Ground Lightning

Abstract A three-dimensional dynamic cloud model incorporating airflow dynamics, microphysics, and thunderstorm electrification mechanisms is used to simulate the first 3 h of the 29 June 2000 supercell from the Severe Thunderstorm Electrification and Precipitation Study (STEPS). The 29 June storm produced large flash rates, predominately positive cloud-to-ground lightning, large hail, and an F1 tornado. Four different simulations of the storm are made, each one using a different noninductive (NI) charging parameterization. The charge structure, and thus lightning polarity, of the simulated storm is sensitive to the treatment of cloud water dependence in the different NI charging schemes. The results from the simulations are compared with observations from STEPS, including balloon-borne electric field meter soundings and flash locations from the Lightning Mapping Array. For two of the parameterizations, the observed “inverted” tripolar charge structure is well approximated by the model. The polarity of the ground flashes is opposite that of the lowest charge region of the inverted tripole in both the observed storm and the simulations. Total flash rate is well correlated with graupel volume, updraft volume, and updraft mass flux. However, there is little correlation between total flash rate and maximum updraft speed. Based on the correlations found in both the observed and simulated storm, the total flash rate appears to be most representative of overall storm intensity.

The 29 June 2000 Supercell Observed during STEPS. Part II: Lightning and Charge Structure

2005 ◽  
Vol 62 (12) ◽  
pp. 4151-4177 ◽  
Author(s):  
Kyle C. Wiens ◽  
Steven A. Rutledge ◽  
Sarah A. Tessendorf
Keyword(s):  
Positive Charge ◽  
Lightning Activity ◽  
Structure Evolution ◽  
Severe Thunderstorm ◽  
Charge Structure ◽  
Flash Rate ◽  
Lightning Detection ◽  
Mapping Array ◽  
Total Lightning ◽  
Mexico Tech

Abstract This second part of a two-part study examines the lightning and charge structure evolution of the 29 June 2000 tornadic supercell observed during the Severe Thunderstorm Electrification and Precipitation Study (STEPS). Data from the National Lightning Detection Network and the New Mexico Tech Lightning Mapping Array (LMA) are used to quantify the total and cloud-to-ground (CG) flash rates. Additionally, the LMA data are used to infer gross charge structure and to determine the origin locations and charge regions involved in the CG flashes. The total flash rate reached nearly 300 min−1 and was well correlated with radar-inferred updraft and graupel echo volumes. Intracloud flashes accounted for 95%–100% of the total lightning activity during any given minute. Nearly 90% of the CG flashes delivered a positive charge to ground (+CGs). The charge structure during the first 20 min of this storm consisted of a midlevel negative charge overlying lower positive charge with no evidence of an upper positive charge. The charge structure in the later (severe) phase was more complex but maintained what could be roughly described as an inverted tripole, dominated by a deep midlevel (5–9 km MSL) region of positive charge. The storm produced only two CG flashes (both positive) in the first 2 h of lightning activity, both of which occurred during a brief surge in updraft and hail production. Frequent +CG flashes began nearly coincident with dramatic increases in storm updraft, hail production, total flash rate, and the formation of an F1 tornado. The +CG flashes tended to cluster in or just downwind of the heaviest precipitation, which usually contained hail. The +CG flashes all originated between 5 and 9 km MSL, centered at 6.8 km (−10°C), and tapped LMA-inferred positive charge both in the precipitation core and (more often) in weaker reflectivity extending downwind. All but one of the −CG flashes originated from >9 km MSL and tended to strike near the precipitation core.

A Supercell Storm Simulation Using a Nonhydrostatic Cloud-Resolving Model Based on a Hybrid Isentropic-Sigma Vertical Coordinate

2013 ◽  
Vol 141 (4) ◽  
pp. 1204-1215 ◽  
Author(s):  
Michael D. Toy
Keyword(s):  
Mass Flux ◽  
Potential Temperature ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Implicit Time ◽  
Vertical Coordinate ◽  
Model Based ◽  
Supercell Storm ◽  
Coordinate Model ◽  
Isentropic Coordinates

Abstract A three-dimensional simulation of a supercell storm is performed with a nonhydrostatic model based on a hybrid isentropic-sigma vertical coordinate. The coordinate is a terrain-following, height-based coordinate near the surface that smoothly transitions to potential temperature with height. Using isentropic coordinates provides the advantage of having zero cross-coordinate vertical mass flux for adiabatic flow, which virtually eliminates the numerical error in the vertical transport. The model uses an adaptive grid algorithm by which the coordinate surfaces may deviate from their target isentropes to maintain a sufficiently smooth mesh, while allowing the turbulence and vertical motion associated with convection to develop. The storm simulated by the hybrid-coordinate model compares well with simulations by Eulerian-coordinate models, but with the key difference being that the cross-coordinate mass flux is significantly smaller in much of the domain with the hybrid-coordinate model. A semi-implicit time-differencing scheme for numerically stabilizing vertically propagating acoustic modes in isentropic coordinates is also presented in the paper.

Radar and Lightning Observations of Normal and Inverted Polarity Multicellular Storms from STEPS

2007 ◽  
Vol 135 (11) ◽  
pp. 3682-3706 ◽  
Author(s):  
Sarah A. Tessendorf ◽  
Steven A. Rutledge ◽  
Kyle C. Wiens
Keyword(s):  
Los Alamos ◽  
Severe Thunderstorm ◽  
Charge Structure ◽  
Array Data ◽  
Lightning Detection ◽  
Normal Polarity ◽  
Mapping Array ◽  
Intracloud Discharges ◽  
Cg Lightning

Abstract This study discusses radar and lightning observations of two multicellular storms observed during the Severe Thunderstorm Electrification and Precipitation Study. The Lightning Mapping Array data indicated that the charge structure of the 19 June 2000 storm was consistent with a normal polarity tripole, while the 22 June 2000 storm exhibited an overall inverted tripolar charge structure. The 19 June storm consisted of weaker convection and produced little to no hail and moderate total flash rates peaking between 80 and 120 min−1. The cells in the 22 June 2000 storm were much more vigorous, exhibited strong, broad updrafts, and produced large quantities of hail, as well as extraordinary total flash rates as high as 500 min−1. The National Lightning Detection Network (NLDN) indicated that the 19 June storm produced mostly negative cloud-to-ground (CG) lightning, while the 22 June storm produced predominantly positive CG lightning, peaking at 10 min−1 just after two cells merged. However, the Los Alamos Sferic Array indicated that many of the positive CG strokes reported by the NLDN in the 22 June storm were intracloud discharges known as narrow bipolar events. Negative CG lightning was also observed in the 22 June storm, but typically came to ground beneath an inverted dipole in the storm anvil.

Initialization and Numerical Forecasting of a Supercell Storm Observed during STEPS

2005 ◽  
Vol 133 (4) ◽  
pp. 793-813 ◽  
Author(s):  
Juanzhen Sun
Keyword(s):  
Radial Velocity ◽  
Cloud Model ◽  
Precipitation Forecast ◽  
Relative Importance ◽  
Severe Thunderstorm ◽  
Penalty Term ◽  
Supercell Storm ◽  
Wind Analysis ◽  
Storm Evolution ◽  
The Cost

The feasibility of initializing a numerical cloud model with single-Doppler observations and predicting the evolution of thunderstorms has been tested using an observed case of a supercell storm during the Severe Thunderstorm Electrification and Precipitation Study (STEPS). Single-Doppler observations from the Weather Surveillance Radar-1988 Doppler (WSR-88D) at Goodland, Kansas, are assimilated into a cloud-scale numerical model using a four-dimensional variational data assimilation (4DVAR) scheme. A number of assimilation and short-range numerical prediction experiments are conducted. Both the assimilation and prediction results are compared with those of a dual-Doppler synthesis. The prediction results are also verified with reflectivity observations. It is shown that the analysis of the wind field captures the major structure of the storm as revealed by the dual-Doppler synthesis. Thermodynamical and microphysical features retrieved through the dynamical model show consistency with expectations for a deep convective storm. The predicted storm evolution represented by the reflectivity field correlates well with the observations for a 2-h prediction period. The relative importance of the initial fields on the subsequent prediction of the storm evolution is examined by alternately removing the perturbation in each of the initial fields. It is shown that the prediction is most sensitive to the initialization of wind, water vapor, and temperature perturbations. A number of sensitivity experiments for initialization are conducted to show how the initial analysis depends on the application of a cycling procedure, the weights of the smoothness constraint, and the relative importance between the radial velocity and the reflectivity observations. It is found that the application of the cycling procedure improves the analysis and the subsequent forecast. Greater smoothness coefficients of the penalty term in the cost function result in a larger rms difference in the wind analysis, but help spread the information out and improve the forecast slightly. The radial velocity observations play a more important role than the reflectivity in terms of the wind analysis and the subsequent precipitation forecast.

scholarly journals Evolving Complex Electrical Structures of the STEPS 25 June 2000 Multicell Storm

2008 ◽  
Vol 136 (2) ◽  
pp. 741-756 ◽  
Author(s):  
Stephanie A. Weiss ◽  
W. David Rust ◽  
Donald R. MacGorman ◽  
Eric C. Bruning ◽  
Paul R. Krehbiel
Keyword(s):  
Great Plains ◽  
Negative Charge ◽  
Positive Charge ◽  
Three Dimensional ◽  
Lightning Flash ◽  
Severe Thunderstorm ◽  
Electrical Structure ◽  
High Reflectivity ◽  
Maximum Value ◽  
Mapping Array

Abstract Data from a three-dimensional lightning mapping array (LMA) and from two soundings by balloon-borne electric field meters (EFMs) were used to analyze the electrical structures of a multicell storm observed on 25 June 2000 during the Severe Thunderstorm Electrification and Precipitation Study (STEPS). This storm had a complex, multicell structure with four sections, each of whose electrical structure differed from that of the others during all or part of the analyzed period. The number of vertically stacked charge regions in any given section of the storm ranged from two to six. The most complex charge and lightning structures occurred in regions with the highest reflectivity values and the deepest reflectivity cores. Intracloud flashes tended to concentrate in areas with large radar reflectivity values, though some propagated across more than one core of high reflectivity or into the low-reflectivity anvil. Intracloud lightning flash rates decreased as the vertical extent and maximum value of reflectivity cores decreased. Cloud-to-ground flash rates increased as cores of high reflectivity descended to low altitudes. Most cloud-to-ground flashes were positive. All observed positive ground flashes initiated between the lowest-altitude negative charge region and a positive charge region just above it. The storm’s complexity makes it hard to classify the vertical polarity of its overall charge structure, but most of the storm had a different vertical polarity than what is typically observed outside the Great Plains. The electrical structure can vary considerably from storm to storm, or even within the same storm, as in the present case.

Microwave Simulations of a Tropical Rainfall System with a Three-Dimensional Cloud Model

1991 ◽  
Vol 30 (7) ◽  
pp. 924-953 ◽  
Author(s):  
Robert F. Adler ◽  
Hwa-Young M. Yeh ◽  
N. Prasad ◽  
Wei-Kuo Tao ◽  
Joanne Simpson
Keyword(s):  
Life Cycle ◽  
Brightness Temperature ◽  
Cloud Model ◽  
Three Dimensional ◽  
Cloud Water ◽  
Radiative Transfer Model ◽  
Squall Line ◽  
Mature Stage ◽  
Convective System ◽  
Transfer Model

Abstract A three-dimensional cloud model-microwave radiative transfer model combination is used to study the relations among the precipitation and other microphysical characteristics of a tropical oceanic squall line and the upwelling radiance at pertinent microwave frequencies. Complex brightness temperature-rain rate relations are evident at the full horizontal resolution (1.5 km) of the models, with spatial avenging producing smoother, shifted relations, in most cases. Nonprecipitating cloud water is shown to be important in understanding the resulting distribution of brightness temperature. At the mature stage, convective portions of the cloud system are shown to produce different brightness temperature relations than the stratiform portion, primarily related to the distribution of cloud water. The evolution of the convective system from a small convective complex through its mature stage and the beginning of its dissipation also is shown to result in a variation of brightness temperature-rain relations, related to the distribution of cloud water and the evolution of ice in the precipitating system. The results of the study paint to the need to take into account the evolution of nonprecipitating cloud water and precipitation-sized ice in the retrieval of rain team from microwave space observations. This effect is evident for both the life cycle of individual convective elements and the life cycle of the convective system as a whole.

scholarly journals Analysis on the Evolution and Microphysical Characteristics of Two Consecutive Hailstorms in Spring in Yunnan, China

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 63
Author(s):  
Sidou Zhang ◽  
Shiyin Liu ◽  
Tengfei Zhang
Keyword(s):  
Wind Speed ◽  
Cloud Model ◽  
Global Analysis ◽  
Maximum Velocity ◽  
Western Pacific Subtropical High ◽  
Convective Cloud ◽  
Radar Data ◽  
Reanalysis Data ◽  
Cloud Water ◽  
High Level

By using products of the cloud model, National Centers for Environmental Prediction (NCEP) Final Operational Global Analysis (FNL) reanalysis data, and Doppler weather radar data, the mesoscale characteristics, microphysical structure, and mechanism of two hail cloud systems which occurred successively within 24 h in southeastern Yunnan have been analyzed. The results show that under the influence of two southwest jets in front of the south branch trough (SBT) and the periphery of the western Pacific subtropical high (WPSH), the northeast-southwest banded echoes affect the southeastern Yunnan of China twice. Meanwhile, the local mesoscale radial wind convergence and uneven wind speed lead to the intense development of convective echoes and the occurrence of hail. The simulated convective cloud bands are similar to the observation. The high-level mesoscale convergence line leads to the development of convective cloud bands. The low-level wind direction or wind speed convergence and the high-level wind speed divergence form a deep tilted updraft, with the maximum velocity of 15 m·s−1 at the −40~−10 °C layer, resulting in the intense development of local convective clouds. The hail embryos form through the conversion or collision growth of cloud water and snowflakes and have little to do with rain and ice crystals. Abundant cloud water, especially the accumulation region of high supercooled water (cloud water) near the 0 °C layer, is the key to the formation of hail embryos, in which qc is up to 1.92 g·kg−1 at the −4~−2 °C layer. The hail embryos mainly grow by collision-coalescence (collision-freezing) with cloud water (supercooled cloud drops) and snow crystal riming.

scholarly journals Lightning in the Anvils of Supercell Thunderstorms

2012 ◽  
Vol 140 (7) ◽  
pp. 2064-2079 ◽  
Author(s):  
Stephanie A. Weiss ◽  
Donald R. MacGorman ◽  
Kristin M. Calhoun
Keyword(s):  
Warm Season ◽  
Opposite Polarity ◽  
Layer Charge ◽  
Supercell Storm ◽  
Lightning Detection ◽  
Supercell Storms ◽  
Mapping Array ◽  
Storm Dynamics ◽  
Supercell Thunderstorms

Abstract This study uses data from the Oklahoma Lightning Mapping Array (OK-LMA), the National Lightning Detection Network, and the Norman, Oklahoma (KOUN), prototype Weather Surveillance Radar-1988 Doppler (WSR-88D) radar to examine the evolution and structure of lightning in the anvils of supercell storms as they relate to storm dynamics and microphysics. Several supercell storms within the domain of the OK-LMA were examined to determine whether they had lightning in the anvil region, and if so, the time and location of the initiation of the anvil flashes were determined. Every warm-season supercell storm had some flashes that were initiated in or near the stronger reflectivities of the parent storm and propagated 40–70 km downstream to penetrate well into the anvil. Some supercell storms also had flashes that were initiated within the anvil itself, 40–100 km beyond the closest 30-dBZ contour of the storm. These flashes were typically initiated in one of three locations: 1) coincident with a local reflectivity maximum, 2) between the uppermost storm charge and a screening-layer charge of opposite polarity near the cloud boundary, or 3) in a region in which the anvils from two adjoining storms intersected. In some storms, anvil flashes struck ground beneath a reflectivity maximum in which reflectivity ≥20 dBZ had extended below the 0°C isotherm, possibly leading to the formation of embedded convection. This relationship may be useful for identifying regions in which there is a heightened risk for cloud-to-ground strikes beneath anvil clouds. In one storm, however, anvil lightning struck ground even though this reflectivity signature was absent.

Three-dimensional flow of Powell–Eyring nanofluid with heat and mass flux boundary conditions

2016 ◽  
Vol 25 (7) ◽  
pp. 074701 ◽  
Author(s):  
Tasawar Hayat ◽  
Ikram Ullah ◽  
Taseer Muhammad ◽  
Ahmed Alsaedi ◽  
Sabir Ali Shehzad
Keyword(s):  
Boundary Conditions ◽  
Mass Flux ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Flux Boundary Conditions

scholarly journals GEOREFERENCING AND REPROJECTION ERROR INVESTIGATION ON IMAGE BASED 3D DIGITIZATION AND MAPPING OF HISTORICAL BUILDINGS

2019 ◽  
Vol XLII-2/W11 ◽  
pp. 71-75
Author(s):  
C. Altuntas
Keyword(s):  
Point Cloud ◽  
Large Scale ◽  
Cloud Model ◽  
Low Cost ◽  
Three Dimensional ◽  
Control Points ◽  
Historical Buildings ◽  
Reprojection Error ◽  
Dense Point ◽  
Point Cloud Model

<p><strong>Abstract.</strong> Image based dense point cloud creation is easy and low-cost application for three dimensional digitization of small and large scale objects and surfaces. It is especially attractive method for cultural heritage documentation. Reprojection error on conjugate keypoints indicates accuracy of the model and keypoint localisation in this method. In addition, sequential registration of the images from large scale historical buildings creates big cumulative registration error. Thus, accuracy of the model should be increased with the control points or loop close imaging. The registration of point point cloud model into the georeference system is performed using control points. In this study historical Sultan Selim Mosque that was built in sixteen century by Great Architect Sinan was modelled via photogrammetric dense point cloud. The reprojection error and number of keypoints were evaluated for different base/length ratio. In addition, georeferencing accuracy was evaluated with many configuration of control points with loop and without loop closure imaging.</p>

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