scholarly journals Explicitly Simulated Electrification and Lightning within a Tropical Cyclone Based on the Environment of Hurricane Isaac (2012)

2015 ◽  
Vol 72 (11) ◽  
pp. 4167-4193 ◽  
Author(s):  
Alexandre O. Fierro ◽  
Edward R. Mansell ◽  
Conrad L. Ziegler ◽  
Donald R. MacGorman
Keyword(s):  
Tropical Cyclone ◽  
Negative Charge ◽  
Lightning Activity ◽  
Ice Crystals ◽  
Weather Research And Forecasting ◽  
The Earth ◽  
Ice Water Path ◽  
Total Lightning ◽  
Ice Water ◽  
Positively Charged

Abstract This work analyzes a high-resolution 350-m simulation of the electrification processes within a hurricane in conjunction with available total lightning observations to augment the general understanding of some of the key cloud-scale electrification processes within these systems. The general environment and trends of Hurricane Isaac (2012), whose lightning activity was observed by the Earth Networks Total Lightning Network, were utilized to produce a reasonable tropical cyclone simulation. The numerical model in this work employs explicit electrification and lightning parameterizations within the Weather Research and Forecasting Model. Overall, simulated storm-total flash origin density rates remain comparable to the observations. Because simulated reflectivities were larger and echo tops were higher in the eyewall than observed, the model consistently overestimated lightning rates there. The gross vertical charge structure in the eyewall resembled a normal tripole or a positive dipole, depending on the location. The negative charge at middle levels and positive at upper levels arose primarily from noninductive charging between graupel and ice crystals/snow. As some graupel melted into rain, the main midlevel negative charge region extended down to the surface in some places. The large volume of positively charged snow aloft caused a radially extensive negative screening layer to form on the lighter ice crystals above it. Akin to continental storms and tropical convection, lightning activity in the eyewall was well correlated with the ice water path (r > 0.7) followed by the graupel + hail path (r ≈ 0.7) and composite reflectivity at temperatures less than −10°C and the snow + ice path (r ≈ 0.5). Relative maxima in updraft volume, graupel volume, and total lightning rates in the eyewall all were coincident with the end of an intensification phase.

Intraseasonal Forcing of Convection and Lightning Activity in the Southern Amazon as a Function of Cross-Equatorial Flow

2006 ◽  
Vol 19 (13) ◽  
pp. 3180-3196 ◽  
Author(s):  
Walter A. Petersen ◽  
Rong Fu ◽  
Mingxuan Chen ◽  
Richard Blakeslee
Keyword(s):  
Wind Shear ◽  
Lightning Activity ◽  
Lightning Flash ◽  
Easterly Wind ◽  
Water Path ◽  
Low Level ◽  
Ice Water Path ◽  
Stratiform Precipitation ◽  
Ice Water ◽  
Thermodynamic Instability

Abstract This study focuses on modulation of lightning and convective vertical structure in the southern Amazon as a function of the South American monsoon V index (VI). Four wet seasons (December–March 1998–2001) of Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (LIS) and Precipitation Radar (PR) data are examined together with two wet seasons (2000–01) of ground-based Brazilian Lightning Detection Network (BLDN) data. These observations are composited by VI phase (northerly or southerly) for a region of the southern Amazon and discussed relative to VI-regime environmental characteristics such as thermodynamic instability and wind shear. Relative comparisons of VI-regime convective properties reveal 1) slightly larger (20%–25%) PR pixel-mean rainfall during periods of northerly VI due to increased stratiform precipitation, 2) a factor of 2 or more increase in lightning flash density and the lightning diurnal cycle amplitude during periods of southerly VI, 3) a factor of 1.5–2 increase in the conditional probability of any PR radar reflectivity pixel exceeding 30 dBZ above the −10°C level during periods of southerly VI, and 4) an associated factor of 2 or more increase in southerly VI pixel-mean ice water path, with the ice water path being highly correlated to trends in lightning activity. During periods of southerly VI, convection occurs in an environment of increased thermodynamic instability, weak southeasterly low-level, and deep upper-tropospheric easterly wind shear. During periods of northerly VI, low-level westerly shear opposes stronger deep tropospheric easterly shear in a relatively moist environment of weaker thermodynamic instability, consistent with the occurrence of more widespread stratiform precipitation. The composite results of this study point to 1) regime differences in convective forcing that alter the prevalence of ice processes and, by inference, the vertical profile of latent heating and 2) the utility of lightning observations in delineating convective regime changes.

scholarly journals Possible Aerosol Effects on Lightning Activity and Structure of Hurricanes

2008 ◽  
Vol 65 (12) ◽  
pp. 3652-3677 ◽  
Author(s):  
A. Khain ◽  
N. Cohen ◽  
B. Lynn ◽  
A. Pokrovsky
Keyword(s):  
Tropical Cyclone ◽  
Mesoscale Model ◽  
Cloud Model ◽  
Aerosol Particles ◽  
Supercooled Water ◽  
Lightning Activity ◽  
Ice Crystals ◽  
Cloud Base ◽  
Weekly Cycle ◽  
Aerosol Effects

Abstract According to observations of hurricanes located relatively close to the land, intense and persistent lightning takes place within a 250–300-km radius ring around the hurricane center, whereas the lightning activity in the eyewall takes place only during comparatively short periods usually attributed to eyewall replacement. The mechanism responsible for the formation of the maximum flash density at the tropical cyclone (TC) periphery is not well understood as yet. In this study it is hypothesized that lightning at the TC periphery arises under the influence of small continental aerosol particles (APs), which affect the microphysics and the dynamics of clouds at the TC periphery. To show that aerosols change the cloud microstructure and the dynamics to foster lightning formation, the authors use a 2D mixed-phase cloud model with spectral microphysics. It is shown that aerosols that penetrate the cloud base of maritime clouds dramatically increase the amount of supercooled water, as well as the ice contents and vertical velocities. As a result, in clouds developing in the air with high AP concentration, ice crystals, graupel, frozen drops and/or hail, and supercooled water can coexist within a single cloud zone, which allows collisions and charge separation. The simulation of possible aerosol effects on the landfalling tropical cyclone has been carried out using a 3-km-resolution Weather Research and Forecast (WRF) mesoscale model. It is shown that aerosols change the cloud microstructure in a way that permits the attribution of the observed lightning structure to the effects of continental aerosols. It is also shown that aerosols, which invigorate clouds at 250–300 km from the TC center, decrease the convection intensity in the TC center, leading to some TC weakening. The results suggest that aerosols change the intensity and the spatial distribution of precipitation in landfalling TCs and can possibly contribute to the weekly cycle of the intensity and precipitation of landfalling TCs. More detailed investigations of the TC–aerosol interaction are required.

scholarly journals The polarity of thunderclouds

1932 ◽  
Vol 138 (834) ◽  
pp. 205-229 ◽  
Keyword(s):  
South Africa ◽  
Negative Charge ◽  
Upper Atmosphere ◽  
Positive Polarity ◽  
The Earth ◽  
Positively Charged

The mechanism of the maintenance of the negative charge upon the surface of the earth has long been sought. C. T. R. Wilson has made the suggestion that the activity of thunderstorms of positive polarity—positively charged above and negatively charged below—will serve to separate positive and negative charges, by carrying negative charges to the earth and positive charges to the upper atmosphere. Experiments carried out by him during and subse­quent to 1916 indicated the presence of clouds predominantly of positive polarity, and similar experiments carried out by Schonland and Craib, in South Africa, gave similar conclusions. Appleton, Watt and Herd made observations on the form of atmospherics, and came to the conclusion that the thunderclouds which were the seat of the disturbances producing atmospherics were of positive polarity.

Changes of Lightning Activity and Vertical Structure in the Inner Core Preceding Tropical Cyclone Rapid Intensification

2020 ◽  
Author(s):  
Weixin Xu
Keyword(s):  
Tropical Cyclone ◽  
Inner Core ◽  
Radar Reflectivity ◽  
Lightning Activity ◽  
Intensity Change ◽  
Complete Understanding ◽  
Radar Echo ◽  
Storm Dynamics ◽  
Total Lightning ◽  
Imaging Sensor

<p>Previous studies suggested that lightning activity could be an indicator of Tropical Cyclone (TC) intensity change but their relationships vary greatly and at times appear contradictory. The importance of total lightning for TC intensification study and forecasting applications has also been pinpointed by several studies. Recently, we revisited this problem using 16 years of TRMM Lightning Imaging Sensor (LIS) measurements and found that reduced (elevated) inner-core total lightning marked rapidly intensifying (weakening) TCs, whereas outer rainband total lightning had opposite trends. It is also shown that the reduced lightning frequency in the inner cores of rapidly intensifying storms was coincident with reduced volumes of 30-dBZ radar reflectivity in the mixed-phase cloud region (-5 to -40 oC), suggesting the lack of large ice particles (e.g., graupel) in the inner cores of rapidly intensifying TCs (which is considered to be important for cloud electrification). To better understand the physical process responsible for these results, we have examined the vertical profiles of radar reflectivity, distribution of precipitation/convection, overshooting radar echo tops (CloudSat), and microwave ice scattering signatures provided by GPM and CloudSat overpasses. This data fusion exercise uniquely provides a more complete understanding of storm electrification, convective intensity, ensemble precipitation microphysics, and storm dynamics in relation to TC intensity change. For example, we have distinguished the convective and microphysical structures between rapidly intensifying (RI) TCs with and without enhanced lightning activity, RI and steady-state TCs, and RI and rapidly weakening TCs.</p>

scholarly journals Estimates of Lightning NO<sub>x</sub> Production based on High Resolution OMI NO<sub>2</sub> Retrievals over the Continental US

2019 ◽  
Author(s):  
Xin Zhang ◽  
Yan Yin ◽  
Ronald van der A ◽  
Jeff L. Lapierre ◽  
Qian Chen ◽  
...  
Keyword(s):  
High Resolution ◽  
Nitrogen Oxides ◽  
Production Efficiency ◽  
Careful Consideration ◽  
Weather Research And Forecasting ◽  
Strong Impact ◽  
Ozone Monitoring Instrument ◽  
Upper Troposphere ◽  
The Earth ◽  
Total Lightning

Abstract. Lightning serves as the dominant source of nitrogen oxides (NOx = NO + NO2) in the upper troposphere (UT), with strong impact on ozone chemistry and the hydroxyl radical production. However, the production efficiency (PE) of lightning nitrogen oxides (LNOx) is still quite uncertain (32–1100 mol NO per flash). Satellites measurements are a powerful tool to estimate LNOx directly as compared to conventional platforms. To apply satellite data in both clean and polluted regions, a new algorithm for calculating LNOx has been developed based on the program of new Berkeley High Resolution (BEHR) v3.0B NO2 product and the Weather Research and Forecasting-Chemistry (WRF-Chem) model. LNOx PE over the continental US is estimated using the NO2 product of the Ozone Monitoring Instrument (OMI) satellite and the Earth Networks Total Lightning Network (ENTLN) data. Focusing on the summer season during 2014, we find that the lightning NO2 (LNO2) PE is 44 ± 16 mol NO2 flash-1 and 8 ± 3 mol NO2 stroke-1 while LNOx PE is 120 ± 52 mol NOx flash-1 and 22 ± 9 mol NOx stroke-1. Results reveal that former methods are more sensitive to background NO2 and neglect much of the below-cloud LNO2. As the LNOx parameterization varies in studies, the sensitivity of our calculations to the setting of the amount of lightning NO (LNO) is evaluated. Careful consideration of the ratio of LNO2 to NO2 is also needed, given its large influence on the estimation of LNO2 PE.

scholarly journals The electric fields of South African thunderstorms

1927 ◽  
Vol 114 (767) ◽  
pp. 229-243 ◽  
Keyword(s):  
South African ◽  
Electric Fields ◽  
Negative Charge ◽  
Reverse Current ◽  
Positive Polarity ◽  
The Earth ◽  
Fine Weather ◽  
Lightning Discharges ◽  
Positively Charged ◽  
Made In

The quantitative study of the electrical changes taking place in thunderstorms was initiated and has been developed by Prof. C. T. R. Wilson in two important papers. Measurements of the electric fields due to charged clouds and of the field changes associated with lightning discharges have led him to put forward certain views according to which the thunderstorm is an important factor in the production and maintenance of several electro-meteorological phenomena with which it has not previously been considered connected. Chief amongst these is the negative charge on the surface of the earth, for the replenishment of which the views of Wilson require a certain preponderance of thunderclouds of positive polarity, i.e ., positively charged above and negatively charged below, over clouds of negative polarity, the ionisation currents between the bases of the clouds of the former type and the ground serving to maintain the earth’s charge at a steady value in spite of the reverse current flowing in regions of fine weather. It is necessary, in order to test this theory, that observations be made in different parts of the world to examine whether the required preponderance of clouds of positive polarity exist. For this purpose South Africa, which contributes largely to the world’s supply of thunderstorms, is very suitable.

scholarly journals Potential of Hyperspectral Thermal Infrared Spaceborne Measurements to Retrieve Ice Cloud Physical Properties: Case Study of IASI and IASI-NG

2020 ◽  
Vol 13 (1) ◽  
pp. 116
Author(s):  
Lucie Leonarski ◽  
Laurent C.-Labonnote ◽  
Mathieu Compiègne ◽  
Jérôme Vidot ◽  
Anthony J. Baran ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Signal To Noise Ratio ◽  
Thermal Infrared ◽  
Radiative Transfer Model ◽  
Retrieval Algorithm ◽  
Transfer Model ◽  
Water Path ◽  
Ice Cloud ◽  
Ice Water Path ◽  
Ice Water

The present study aims to quantify the potential of hyperspectral thermal infrared sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) and the future IASI next generation (IASI-NG) for retrieving the ice cloud layer altitude and thickness together with the ice water path. We employed the radiative transfer model Radiative Transfer for TOVS (RTTOV) to simulate cloudy radiances using parameterized ice cloud optical properties. The radiances have been computed from an ice cloud profile database coming from global operational short-range forecasts at the European Center for Medium-range Weather Forecasts (ECMWF) which encloses the normal conditions, typical variability, and extremes of the atmospheric properties over one year (Eresmaa and McNally (2014)). We performed an information content analysis based on Shannon’s formalism to determine the amount and spectral distribution of the information about ice cloud properties. Based on this analysis, a retrieval algorithm has been developed and tested on the profile database. We considered the signal-to-noise ratio of each specific instrument and the non-retrieved atmospheric and surface parameter errors. This study brings evidence that the observing system provides information on the ice water path (IWP) as well as on the layer altitude and thickness with a convergence rate up to 95% and expected errors that decrease with cloud opacity until the signal saturation is reached (satisfying retrievals are achieved for clouds whose IWP is between about 1 and 300 g/m2).

Predicting lightning activity in Greece with the Weather Research and Forecasting (WRF) model

2015 ◽  
Vol 156 ◽  
pp. 1-13 ◽  
Author(s):  
Theodore M. Giannaros ◽  
Vassiliki Kotroni ◽  
Konstantinos Lagouvardos
Keyword(s):  
Wrf Model ◽  
Lightning Activity ◽  
Weather Research And Forecasting ◽  
Weather Research
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