Atmospheric Electricity: Papers on Thunderstorm and Cloud Electricity

Abstract:

Problems of thunderstorm and cloud electricity still remain in the mainstream of research of atmospheric physics researchers. Hence, in this special issue of Publications of the Institute of Geophysics, Polish Academy of Sciences, devoted to problems of atmospheric electricity, we present a set of six articles in which we publish some recent results on this subject, obtained by us and our co-workers.

Abstract:

The paper presents the results of spatial location (in the coordinates of the local and rectangular Cartesian system: x, y, z) as well as the polarity and electric charge of all sources in thunderclouds discharged by individual return strokes during 17 multiple cloud-to-ground discharges recorded simultaneously by six measurement stations of the LLDN (Local Lightning Detection Network) system located in the Warsaw region in the spring and summer season of 2009. The post-time analysis of the collected digital electric field records of these discharges was carried out based on our own calculation algorithms, described in detail by Baranski et al. (2012). In turn, for two selected discharges from this group, one positive double ground flash from the 25 June 2009 storm and the other negative threefold ground flash from the 5 July 2009 storm, the supplementary simulations of radar reflectivity, the structure of the wind field and the thundercloud electric charge density were obtained from the WRF and WRF_ELEC models. Due to this, it was possible to distinguish with the time resolution up to 1 minute such regions of the thundercloud in which the simulated wind field and electric charge densities with different polarity created favourable conditions to initiate all return strokes of the considered multiple ground flashes and detected by the LLDN network. It also should be noted that the time resolution in the available routine radar observations from the IMWM-NRI is by one order of magnitude worse than the one delivered by the WRF simulations and amounts to 10 minutes.

Abstract:

This paper provides details on meteorological and atmospheric electricity datasets and the methodology of analysis of the atmospheric electric data from the Polish Atmospheric Electricity Observation Network used for the purpose of research studies of the electricity of Nimbostratus and Stratus clouds and their role in the global atmospheric electric circuit.

Abstract:

Nigh-time observations of red sprites phenomena over thunderstorm seasons of 2011–2013 from Gliwice (52.116°N, 21.238°E) resulted in 45 events observed above convective storm system in the Czech Republic, Germany, and south-western Poland. This paper gives details of the observed events along with the correlation of optical data with cloud-to-ground and in-cloud lightning recorded by the CELDN lightning detection system. We also analyse the time sequence and locations of parent lightning in dancing sprites events produced at various stages of the thundercloud development and sprite production using visualisation of their locations mapped onto the “overshooting-tops” satellite images derived from Meteosat SEVIRI instrument data.

Abstract:

In 2012–2015, during the peak of thunderstorm season (June–August), night-time optical observations of lightning discharges above storm clouds, called sprites, were conducted from the Geophysical Observatory of the Institute of Geophysics of the Polish Academy of Sciences in Świder (52.115°N, 21.238°E). Dozens of phenomena were recorded above mesoscale convective storm systems located in western and northern Poland, the Baltic Sea, Russia, and Lithuania. Details of the observed events are presented, along with the correlation of optical data with cloud-to-ground and in-cloud lightning recorded by the IMWM-NRI PERUN lightning detection and location system. The analysis concludes with statistics of the observed sprite forms in relation to the associated parent lightning.

Abstract:

We present technical details of the TV observations of sprite lightning phenomena made from Gliwice and Świder in 2011–2015, and propose methods of verification and corrections to the recorded timing of individual cases and series of events.

Abstract:

Everyone agrees that the episode of the derecho of 11 August 2017, commonly known as “Suszek”, was the most catastrophic weather event in Poland of the last decade. This case of a rapidly and very fast-moving mesoscale convection system (MCS) is still being analyzed. The current work uses the lightning detection data from the PERUN remote sensing system, which allowed to estimate the electrical activity of such a huge convection system. The primary lightning discharge density is then transformed into the useful scalar parameter, i.e., the predictor characterizing lightning and convection severity of the considered MCS and denoted farther as the virtual Fujita scale (VFS) number. The scrutinized analysis conducted by us presents firstly the detailed mapping of disturbance involved in the MCS propagation path by using the moving filters approach, secondly the area determination of the MCS event development in the form of a mask, and thirdly the analysis of selected aspects of the phenomenology of the MCS occurrence. Such filters make it possible to split the main space domain of the considered convection area into two separated parts of each filter, i.e., its west and east flanks/sides. 
    A refined analysis and comparison of the aside thunderstorm tracks allowed us to better characterize the development structure of the considered MCS region. In this case, the meteorological context of the MCS episode, i.e., the influence of synoptic background on the course of such a convection, was essential. A better understanding of this violent convective process requires a detailed and complex diagnosis of the complementary and additional information coming from various measurement and database sources, e.g., the ground meteorological measurements, lightning discharges detections and locations, radar and satellite observations together with the relevant model simulations and various severe weather reports. In turn, the used data should be projected/presented in the common and one reference grid. This common reference context was provided by the operational computer simulations at 12:00 and 18:00 GMT of the derecho day expressed by the study of the 3D fields of such parameters as the air pressure, the potential temperature of the tropopause, the air vorticity, the vertical component of air motion and the turbulence air potential. This last was broken down into two components related to the Reynolds and Richardson numbers. The first component represents momentum and is denoted further as PTRe and the second one, relevant to buoyancy and the air flow shear, is denoted by PTRi. The presented approach allowed for a rational tracking of the evolution of the whole MCS system connected with the derecho episode in Poland.