Supercell thunderstorm charge structure variability and influences on spatial lightning flash relationships with the updraft

Monthly Weather Review ◽

10.1175/mwr-d-21-0071.1 ◽

2021 ◽

Author(s):

Christopher J. Schultz ◽

Daniel J. Cecil

Keyword(s):

Negative Charge ◽

Spatial Scales ◽

Subsequent Development ◽

Lightning Flash ◽

Charge Structure ◽

Kinematic Characteristics ◽

Tennessee Valley ◽

Initial Charge ◽

Supercell Thunderstorm ◽

Cloud Ice

Abstract Relationships between lightning flashes and thunderstorm kinematics and microphysics are important for applications such as nowcasting of convective intensity. These relationships are influenced by cloud electrification structures and have been shown to vary in anomalously electrified thunderstorms. This study addresses transitional relationships between active charge structure and lightning flash location in the context of kinematic and microphysical updraft characteristics during the development of an anomalously electrified supercell thunderstorm in the Tennessee Valley on 10 April 2009. The initial charge structure within the updraft was characterized as an anomalous dipole in which positive charge was inferred in regions of precipitation ice (i.e., graupel and hail) and negative charge was inferred in regions of cloud ice (i.e., aggregates and ice crystals). During subsequent development of the anomalous charge structure, additional minor charge layers as well as evidence of increasing horizontal complexity were observed. Microphysical and kinematic characteristics of the charge structure also evolved to include increasing observations of negative charge in precipitation ice regions, indicating the emergence of more prominent normal charging alongside dominant anomalous charging. Simultaneously, lightning flash initiation locations were also increasingly observed in regions of faster updrafts and stronger horizontal gradients in updraft speed. It is suggested that continuous variability in charging behavior over meso-gamma spatial scales influenced the evolution of lightning flash locations with respect to the updraft structure. Further work is necessary to determine how this variability may impact lightning flash relation-ships, including lightning flash rate, with bulk microphysical and kinematic characteristics and related applications.

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Effects of Temperature and Charge Depletion on the Spin Density in Hydrogenated Amorphous Silicon

MRS Proceedings ◽

10.1557/proc-219-605 ◽

1991 ◽

Vol 219 ◽

Author(s):

J.-K. Lee ◽

E. A. Schiff

Keyword(s):

Spin Density ◽

Negative Charge ◽

Temperature Dependent ◽

Defect Model ◽

Depletion Width ◽

Initial Charge ◽

Effects Of Temperature ◽

Hydrogenated Amorphous ◽

Spin Densities ◽

Charge Depletion

ABSTRACTThe dependence of the spin density upon temperature and charge depletion is calculated based on the standard defect model in a-Si:H of a D-center with positive, neutral, and negative charge states. The results are compared with recent measurements of depletion width modulated spin densities and temperature-dependent spin densities. It is shown that the initial charge density assumed for the defect system substantially affects conclusions regarding electronic correlation energies drawn from the measurements.

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A numerical study of hail process effects on charge structure and lightning flash rate of thunderstorms

2016 Asia-Pacific International Symposium on Electromagnetic Compatibility (APEMC) ◽

10.1109/apemc.2016.7522807 ◽

2016 ◽

Author(s):

Weiqi Gao ◽

Zheng Kou ◽

Pengfei Ding

Keyword(s):

Numerical Study ◽

Lightning Flash ◽

Charge Structure ◽

Flash Rate ◽

Process Effects

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Using cloud ice flux to parametrise large-scale lightning

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-17817-2014 ◽

2014 ◽

Vol 14 (12) ◽

pp. 17817-17856 ◽

Cited By ~ 1

Author(s):

D. L. Finney ◽

R. M. Doherty ◽

O. Wild ◽

H. Huntrieser ◽

H. C. Pumphrey ◽

...

Keyword(s):

Large Scale ◽

Climate Models ◽

Tropical Rainfall Measuring Mission ◽

Reanalysis Data ◽

Lightning Flash ◽

Spatial Correlations ◽

Zonal Distribution ◽

Annual Total ◽

Cloud Ice ◽

Mean Square Errors

Abstract. Lightning is an important natural source of nitrogen oxide especially in the middle and upper troposphere. Hence, it is essential to represent lightning in chemistry transport and coupled chemistry-climate models. Using ERA-Interim meteorological reanalysis data we compare the lightning flash density distributions produced using several existing lightning parametrisations, as well as a new parametrisation developed on the basis of upward cloud ice flux at 440 hPa. The use of ice flux forms a link to the non-inductive charging mechanism of thunderstorms. Spatial and temporal distributions of lightning flash density are compared to tropical and subtropical observations for 2007–2011 from the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission satellite. The well-used lightning flash parametrisation based on cloud-top height has large biases but the derived annual total flash density has a better spatial correlation with the LIS observations than other existing parametrisations. A comparison of flash density simulated by the different schemes shows that the cloud-top height parametrisation has many more instances of moderate flash densities and fewer low and high extremes compared to the other parametrisations. Other studies in the literature have shown that this feature of the cloud-top height parametrisation is in contrast to lightning observations over certain regions. Our new ice flux parametrisation shows a clear improvement over all the existing parametrisations with lower root mean square errors and better spatial correlations with the observations for distributions of annual total, and seasonal and interannual variations. The greatest improvement with the new parametrisation is a more realistic representation of the zonal distribution with a better balance between tropical and subtropical lightning flash estimates. The new parametrisation is appropriate for testing in chemistry transport and chemistry-climate models that use a lightning parametrisation.

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Thunderstorm Classification Functions Based on Instability Indices and GNSS IWV for the Sofia Plain

10.5194/egusphere-egu21-1819 ◽

2021 ◽

Author(s):

Guergana Guerova ◽

Tsvetelina Dimitrova ◽

Stefan Georgiev

Keyword(s):

Satellite System ◽

Probability Of Detection ◽

Radiosonde Data ◽

Lightning Flash ◽

Path Delay ◽

Statistical Regression ◽

Period Analysis ◽

Supercell Thunderstorm ◽

Global Navigation Satellite ◽

Instability Indices

<p>Bulgaria is a country with a high frequency of hail and thunderstorms from May to September. For the May&#8211;September 2010&#8211;2015 period, statistical regression analysis was applied to identify predictors/classification functions that contribute skills to thunderstorm forecasting in the Sofia plain. The functions are based on (1) instability indices computed from radiosonde data from Sofia station F1, and (2) combination of instability indices and Integrated Water Vapor (IWV), derived from the Global Navigation Satellite System (GNSS) station Sofia-Plana, F2. Analysis of the probability of detection and the false alarm ratio scores showed the superiority of the F2 classification function, with the best performance in May, followed by June and September. F1 and F2 scores were computed for independent data samples in the period 2017&#8211;2018 and confirmed the findings for the 2010&#8211;2015 period. Analysis of IWV and lightning flash rates for a multicell and supercell thunderstorm in June and July 2014 showed that the monthly IWV thresholds are reached 14.5 and 3.5 hours before the thunderstorm, respectively. The supercell IWV peak registered 40 min before the thunderstorm, followed by a local IWV minimum corresponding to a peak in the flash rate. In both cases, an increase of IWV during severe hail was registered, which is likely related to the hydrometeor contribution to GNSS path delay. The results of this study will be integrated into the Bulgarian Integrated NowCAsting tool for thunderstorm forecasting in the warm/convective season.</p>

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Simulated Electrification of a Small Thunderstorm with Two-Moment Bulk Microphysics

Journal of the Atmospheric Sciences ◽

10.1175/2009jas2965.1 ◽

2010 ◽

Vol 67 (1) ◽

pp. 171-194 ◽

Cited By ~ 205

Author(s):

Edward R. Mansell ◽

Conrad L. Ziegler ◽

Eric C. Bruning

Keyword(s):

Charge Separation ◽

Negative Charge ◽

Positive Charge ◽

Model Simulation ◽

Particle Density ◽

Phase Region ◽

Number Concentration ◽

Ice Crystals ◽

Microphysics Scheme ◽

Charge Structure

Abstract Electrification and lightning are simulated for a small continental multicell storm. The results are consistent with observations and thus provide additional understanding of the charging processes and evolution of this storm. The first six observed lightning flashes were all negative cloud-to-ground (CG) flashes, after which intracloud (IC) flashes also occurred between middle and upper levels of the storm. The model simulation reproduces the basic evolution of lightning from low and middle levels to upper levels. The observed lightning indicated an initial charge structure of at least an inverted dipole (negative charge above positive). The simulations show that noninductive charge separation higher in the storm can enhance the main negative charge sufficiently to produce negative CG flashes before upper-level IC flashes commence. The result is a “bottom-heavy” tripole charge structure with midlevel negative charge and a lower positive charge region that is more significant than the upper positive region, in contrast to the traditional tripole structure that has a less significant lower positive charge region. Additionally, the occurrence of cloud-to-ground lightning is not necessarily a result of excess net charge carried by the storm, but it is primarily caused by the local potential imbalance between the lowest charge regions. The two-moment microphysics scheme used for this study predicted mass mixing ratio and number concentration of cloud droplets, rain, ice crystals, snow, and graupel. Bulk particle density of graupel was also predicted, which allows a single category to represent a greater range of particle characteristics. (An additional hail category is available but was not needed for the present study.) The prediction of hydrometeor number concentration is particularly critical for charge separation at higher temperatures (−5° < T < −20°C) in the mixed phase region, where ice crystals are produced by rime fracturing (Hallett–Mossop process) and by splintering of freezing drops. Cloud droplet concentration prediction also affected the rates of inductive charge separation between graupel and droplets.

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Using cloud ice flux to parametrise large-scale lightning

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-12665-2014 ◽

2014 ◽

Vol 14 (23) ◽

pp. 12665-12682 ◽

Cited By ~ 23

Author(s):

D. L. Finney ◽

R. M. Doherty ◽

O. Wild ◽

H. Huntrieser ◽

H. C. Pumphrey ◽

...

Keyword(s):

Large Scale ◽

Climate Models ◽

Tropical Rainfall Measuring Mission ◽

Reanalysis Data ◽

Lightning Flash ◽

Spatial Correlations ◽

Zonal Distribution ◽

Annual Total ◽

Cloud Ice ◽

Mean Square Errors

Abstract. Lightning is an important natural source of nitrogen oxide especially in the middle and upper troposphere. Hence, it is essential to represent lightning in chemistry transport and coupled chemistry–climate models. Using ERA-Interim meteorological reanalysis data we compare the lightning flash density distributions produced using several existing lightning parametrisations, as well as a new parametrisation developed on the basis of upward cloud ice flux at 440 hPa. The use of ice flux forms a link to the non-inductive charging mechanism of thunderstorms. Spatial and temporal distributions of lightning flash density are compared to tropical and subtropical observations for 2007–2011 from the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite. The well-used lightning flash parametrisation based on cloud-top height has large biases but the derived annual total flash density has a better spatial correlation with the LIS observations than other existing parametrisations. A comparison of flash density simulated by the different schemes shows that the cloud-top height parametrisation has many more instances of moderate flash densities and fewer low and high extremes compared to the other parametrisations. Other studies in the literature have shown that this feature of the cloud-top height parametrisation is in contrast to lightning observations over certain regions. Our new ice flux parametrisation shows a clear improvement over all the existing parametrisations with lower root mean square errors (RMSEs) and better spatial correlations with the observations for distributions of annual total, and seasonal and interannual variations. The greatest improvement with the new parametrisation is a more realistic representation of the zonal distribution with a better balance between tropical and subtropical lightning flash estimates. The new parametrisation is appropriate for testing in chemistry transport and chemistry–climate models that use a lightning parametrisation.

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Cloud ice fraction governs lightning rate at a global scale

Communications Earth & Environment ◽

10.1038/s43247-021-00233-4 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Yong Han ◽

Hao Luo ◽

Yonghua Wu ◽

Yijun Zhang ◽

Wenjie Dong

Keyword(s):

Global Scale ◽

Cloud Microphysics ◽

Lightning Flash ◽

Ice Clouds ◽

Flash Rate ◽

Convective Clouds ◽

Function Relationship ◽

Cloud Ice ◽

Cloud Thickness ◽

Ice Fraction

AbstractLightning flash rate is strongly influenced by cloud microphysics, such as cloud ice properties, but this relationship is poorly constrained. Here we analyze 20 years of satellite-derived lightning flash rate data and cloud water data from the ERA-Interim reanalysis above continental and ocean regions at a global scale. We find a robust modified gamma function relationship between cloud ice fraction and lightning rate. Lightning rate increases initially with increasing cloud ice fraction in stratocumulus, liquid clouds. Maximum flash rates are reached at a critical cloud ice fraction value that is associated with high top, large optical thickness, deep convective clouds. Beyond the critical value, lightning rate decreases as the ice fraction increases to values representative of cirrus, ice clouds. We find consistent critical ice fraction values over continental and oceanic regions, respectively, with a lower value over the continent due to greater cloud thickness at similar cloud top height. We suggest that our findings may help improve the accuracy of lightning forecast and hazard prediction.

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Thunderstorm Classification Functions Based on Instability Indices and GNSS IWV for the Sofia Plain

Remote Sensing ◽

10.3390/rs11242988 ◽

2019 ◽

Vol 11 (24) ◽

pp. 2988 ◽

Cited By ~ 4

Author(s):

Guergana Guerova ◽

Tsvetelina Dimitrova ◽

Stefan Georgiev

Keyword(s):

Satellite System ◽

Probability Of Detection ◽

Radiosonde Data ◽

Lightning Flash ◽

Path Delay ◽

Statistical Regression ◽

Period Analysis ◽

Supercell Thunderstorm ◽

Global Navigation Satellite ◽

Instability Indices

Bulgaria is a country with a high frequency of hail and thunderstorms from May to September. For the May–September 2010–2015 period, statistical regression analysis was applied to identify predictors/classification functions that contribute skills to thunderstorm forecasting in the Sofia plain. The functions are based on (1) instability indices computed from radiosonde data from Sofia station F1, and (2) combination of instability indices and Integrated Water Vapor (IWV), derived from the Global Navigation Satellite System (GNSS) station Sofia-Plana, F2. Analysis of the probability of detection and the false alarm ratio scores showed the superiority of the F2 classification function, with the best performance in May, followed by June and September. F1 and F2 scores were computed for independent data samples in the period 2017–2018 and confirmed the findings for the 2010–2015 period. Analysis of IWV and lightning flash rates for a multicell and supercell thunderstorm in June and July 2014 showed that the monthly IWV thresholds are reached 14.5 and 3.5 hours before the thunderstorm, respectively. The supercell IWV peak registered 40 min before the thunderstorm, followed by a local IWV minimum corresponding to a peak in the flash rate. In both cases, an increase of IWV during severe hail was registered, which is likely related to the hydrometeor contribution to GNSS path delay. The results of this study will be integrated into the Bulgarian Integrated NowCAsting tool for thunderstorm forecasting in the warm/convective season.

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