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Talks and Lectures
Anna Odzimek (Institute of Geophysics PAS, Poland): “Global atmospheric electric circuit (GEC) modelling – a historical perspective and the modern approach”
The talk is concerned with the history and modern approach to atmospheric global circuit (GEC) modelling. First it describes the modelling a research method and the evolution of modeling techniques from mathematical models solved analytically to computer simulations used today. Next, the essential elements to include in any model of the GEC are discussed: the electrical properties of the atmospheric medium, sources generating electrical currents, and coupling with interacting current systems. GEC modelling involves various factors such as atmospheric ionisation, conductivity of the Earth layers, weather, clouds, precipitation, lightning, and solar-terrestrial interactions, and is one the most interdisciplinary topic in Earth science. The goal of the GEC modelling is to quantitatively best illustrate the electric current flow in the atmosphere, and its variations. Approaches include using both equivalent lump circuits and high-resolution circuits, datasets and weather or climate models for deterministic and stochastic simulations.
Brian Tinsley (University of Texas at Dallas, USA): “The influence of the solar wind electric and magnetic fields on the latitude and temporal variations of the current density, Jz, of the global electric circuit, with relevance to weather and climate”
The downward current density JZ in the global electric circuit is affected by two inputs from space weather: solar wind electric fields and solar wind magnetic fields. The solar wind electric fields affect the ionospheric potential Vi, mainly at geomagnetic latitudes above 75⁰. The solar wind magnetic fields affect the energy spectrum of galactic cosmic rays, (GCR), and temporal and latitudinal variations in local column resistance, R, more so above 45⁰ gmlat. than lower latitudes. JZ = Vi/R. The JZ time variations due to Vi are mainly on the day-to-day timescale, due to the solar wind sector structure. The JZ time variations due to R are on the day-to-day, 11-year, 22-year, and century timescales. JZ passes through clouds and aerosol layers when they are present, and redistributes ionization to create space charge in them, which attaches to aerosol particles and droplets. I will discuss specific temporal and latitudinal responses to JZ variations, such as of low clouds and storm vorticity and blocking and colder European winters at cosmic ray maxima, as responses to cloud microphysical variations. These involve electro-scavenging, electro-anti-scavenging in space charge regions, and immersion and contact ice nucleation processes.
Artur Szkop (Institute of Geophysics PAS, Poland): “Overview of atmospheric aerosols and their connections with atmospheric electricity”
Atmospheric aerosols, tiny particles suspended in the air, play a pivotal role in both human health and the Earth’s climate system. This speech will explore the various types of aerosols, including natural (e.g., dust, sea spray) and anthropogenic (e.g., industrial emissions, vehicle exhaust). Next we will discuss how aerosols contribute to climate change, influencing both the Earth’s energy balance and regional weather patterns through processes like radiative forcing. Different types of smog events will be described – photochemical and industrial – and their connection to aerosol concentrations. The talk will highlight aerosol-cloud interactions, focusing on how aerosols act as cloud condensation and ice nuclei, modifying cloud properties, precipitation, and, ultimately, climate feedbacks. Finally, we will discuss aerosols’ lesser-known role in atmospheric electricity, particularly their ability to capture ions and influence the conductivity of the air. This interaction is significant for the global atmospheric electric circuit.
Aleksander Pietruczuk (Institute of Geophysics PAS, Poland): “Techniques of aerosol measurements by the example of IGF PAS, Poland”
Accurate measurement of atmospheric aerosols is crucial for understanding their impact on air quality, human health, and climate. This speech will provide an overview of key aerosol measurement techniques, focusing on the distinction between mass concentration measurements, such as PM10, and number size distribution measurements. We will present the working principles of several in-situ instruments: the Mobility Particle Size Spectrometer (MPSS), which measures particle mobility diameter; the Aerodynamic Particle Sizer Spectrometer (APSS), which characterizes particles by their aerodynamic diameter; the Optical Particle Counter (OPC), which detects particles via light scattering; and the nephelometer, which measures aerosol scattering properties to infer concentration. In addition to these ground-based methods, we will explore the connection between in-situ aerosol measurements and remote sensing techniques such as LIDAR and photometers. These remote instruments provide spatially extensive data, complementing the detailed point measurements made by in-situ methods. By integrating these two approaches, we can enhance our understanding of aerosol distribution and dynamics on both local and global scales, ultimately improving air quality monitoring and climate modeling efforts.
Steve Milan (University of Leicester, UK): “Electrodynamics of the solar wind-magnetosphere-ionosphere coupled system”
The interaction between the interplanetary magnetic field (IMF), embedded within the out-flowing solar wind, and the Earth’s magnetosphere produces a complex and dynamic near-Earth environment. Magnetic reconnection at the magnetopause sets the magnetic field and plasma within the magnetosphere into circulation, which in turn couples to the ionosphere, causing it to move through the neutral atmosphere. This sets up a system of electrical currents which flow within the ionosphere and up and down between the ionosphere and the magnetosphere. One of the most visible manifestations of these current systems is the global pattern of auroras. Plasma motions imply the generation of magnetic and electric fields, and a complex electrodynamic coupling between different parts of the system. This talk will briefly outline basic plasma physics, the morphology and dynamics of the coupled magnetosphere-ionosphere system, and its response to driving by the solar wind.
Maria-Theresia Walach (Lancaster University, UK): “Electrodynamic Coupling and Time Variability in the Ionosphere Electric Field”
The ionosphere is coupled to the Earth’s magnetosphere and the solar wind through electrodynamics. The auroral emissions, which we thus see and the electric fields that we can measure have been shown to be dynamic. The electric fields that arise due to solar wind-magnetosphere-ionosphere coupling vary in strength, location and morphology. In this talk, I summarise how we can measure these dynamics, and what the underlying drivers are. I show how we can utilise the Super Dual Auroral Radar Network (SuperDARN) to give us a large-scale and long-term overview of the ionospheric line-of-sight plasma velocity measurements and derived ionospheric electric field. I also introduce a statistical model of the Electric field patterns, built empirically with SuperDARN data. The Time Varying Ionospheric Electric Field (TiVIE) model is produced using an established technique that models the electric field and potential as a spherical harmonic expansion of the ionospheric electric potential. Major improvements over existing models are achieved by the use of novel parameterisations that capture three major sources of time-variability of the coupled solar wind-magnetosphere-ionosphere system: 1) the upstream solar wind conditions, specifically the strength and orientation of the interplanetary magnetic field and the steadiness of the solar wind, 2) substorm onset location as well as the time relative to substorm onset, and 3) the variability introduced by geomagnetic storms. These account for the variability in the magnetosphere-ionosphere system, which occurs even under continuous steady driving by the solar wind. The second source of variability relates to the storage and release of energy in the magnetosphere that is associated with magnetospheric substorms. The electric field evolves throughout the substorms cycle and geomagnetic storm phases, and its morphology is strongly influenced by their occurrences. I discuss the details of the model, and assess its performance by comparison to other models and to observations.
Michael Rycroft (CAESAR Consultancy, UK): “Some key points about the Global Electric Circuit (GEC)”
C T R Wilson conceived the idea of the Global Electric Circuit, and worked on it throughout his long life (1869-1959). He suggested that the DC generators were thunderstorms and electrified shower clouds which drive a current of ~ 1 kA up to the ionosphere, which is an almost equipotential surface at ~ + 250 kV with respect to the Earth’s surface. He measured the downward current through the fair weather atmosphere in 1906 to be ~ 2 pA/m2. In 1927, T W Wormell (my PhD supervisor) published the annual electrical “balance sheet”, in C, of 1 km2 of ground at Cambridge as deduced from his measurements. The circuit is closed by currents flowing in the land and ocean surface, and by point discharge currents up to the bottom of the clouds. Rycroft et al. (2000) drew an electrical engineering circuit diagram representing the GEC, but showed the wrong scale height for variations with altitude. Denisenko et al. (2019) presented a comprehensive theoretical model of the GEC with a representative height profile of the electrical conductivity of the air and where a detailed treatment of the ionospheric physics was given. Observations of the vertical electric field (or potential gradient, PG, with the opposite sign) made on the Carnegie Cruise VII were discussed by Harrison (2013) and by Denisenko and Rycroft (2023), who calculated the equatorial electrojets in the ionosphere produced by thunderstorms. Figures showing both the temporal and spatial scales of AC (Schumann resonance) and various DC GEC phenomena as functions of altitude were presented by Rycroft and Harrison (2011). Rycroft et al. (2024) published new GEC circuit diagrams including low level stratus clouds and volcanic lightning as an additional generator. Their theoretical model for the time constant of the GEC, ~ 8 minutes, was found to be in agreement with its value derived from PG observations made remotely at times of the sudden onset of volcanic lightning in Iceland in 2011 and in Tonga in 2022. This time constant is shown to be consistent with the results of Wormell (1927) and a negative charge of ~ 5 x 105 C on the Earth’s surface, as first considered by Wilson (1920). Recent modelling studies by Surkov et al. (2022) and Denisenko et al. (2024) have shown that it is highly unlikely that changes to the air conductivity due to radon concentration changes associated with seismic activity will produce any significant changes to the ionosphere.
Earle Williams (Massachusetts Institute of Technology, USA): “Chimney Source Quantification based on Single Station Observations of the Schumann Resonance Fundamental Magnetic Mode (8 Hz) at High Latitude”
The global reach of lightning in the lower ELF band is well-recognized. The electromagnetic resonances of the Schumann background and the well-established geolocation and physical characterization of energetic lightning flashes (Q-bursts) stand as evidence. Since the ice-based charge separation process in thunderstorms is gravity-driven, every lightning flash has a vertical component of charge moment change and so contributes to ELF intensity. The two long-standing roadblocks to the quantitative monitoring of lightning source regions (‘chimneys’) at ELF are the overlapping of the separate chimney sources in time and the non-linear distance dependence of the magnetic intensity in the normal mode theory. Ways around both roadblocks have now been identified. Fortuitously, the continental chimney sources (America, Africa and Asia) are separated by 90 degrees (10 Mm) in longitude. Accordingly, a pair of perpendicular induction coils at high-latitude (on the meridian of Africa) can detect exclusively Africa in the EW component, and both America and Asia, each exclusively in the NS component, but separated in time by 12 hours. For polar-latitude receivers, the source-receiver distances are all close to 90 degrees (10 Mm). The requirement for 90 degree (10 Mm) separation is not stringent because the magnetic intensity at 8 Hz is flat with distance near 90 degrees (10 Mm). These ideas have been tested with two widely separated stations, one in the Arctic (Hornsund: 77 N; 16 E) and one in the Antarctic (Maitri: 71 S; 12 E). Despite more than 15 Mm separation, the records of magnetic intensity at 8 Hz at these two sites track each other in fine detail (cc = 0.94), day-by-day and month-by-month. The individual chimney contributions to global lightning activity are readily discernible every day and can be ranked in absolute units of coul2km2/sec. This ranking on any given day can be arbitrary, and so can depart from the conventional America/Africa/Asia ranking often associated with the climatological Carnegie Curve of the DC global circuit. In NH winter months, Africa is often top-ranked. Near vernal equinox, Asia can be dominant.
Masashi Kamogawa (University of Shizuoka, Japan): “Surface atmospheric electric field measurements for global electric circuit studies at Syowa Station, Antarctica: reducing charged snow particle noise from ground snowstorms”
Surface atmospheric electric field observation is highly affected by the polluted air such as aerosol. To investigate the Carnegie curve using the surface atmosphere electric field observation, clear air environment is required. In this context, a polar region is one of the ideal places to observe the surface atmospheric electricity. For this purpose, we started the surface atmospheric electric field measurement since 2011 at Syowa station, Antarctica. Initial observation we installed the tree field mills one of which the probe faced the ground (i.e. using an inverted-kit). All of the sensor had around 1.5-m height. In addition, we install the one field mill with 10-m height. In polar observation, the ideal unpolluted air condition was obtained. However, the blizzard significantly disturbed the atmospheric electricity. In particular, the intense positive electric field (i.e. fair-weather direction) was observed during the large wind velocity. This phenomenon has been often reported. Besides the snow blizzard, the similar intense atmospheric electric field is also observed in the sandstorm in the desert and dust in the factory. To understand the intense positive atmospheric electric field, the Poisson simulation was conducted (Minamoto et al., Atmos. Res., 2011). In the conclusion, the observed intense positive atmospheric electric field is caused by the collision into the probe surface of field mill with the saltating negatively snow particles. Based on this result, we focus on the difference between the atmospheric electric fields at 1.4-m and 10-m height, because this difference is small except the blizzard period (Minamoto et al., J. Geophys. Res., 2023). Introducing the difference threshold as criteria, the fair-weather condition is systematically obtained. Using these criteria, we finally obtained the fine Carnegie curve. Since we obtain the knowledge to discriminate the signal and noise from the measured atmospheric electric field for the global electrical circuit study, we investigate the diurnal variation of surface atmospheric electric field during the magnetic storm (Minamoto, PhD thesis, 2022). Less magnetic storm the fine Carnegie curve appears, lager magnetic storm the modulated variation appears. Our new data from the field mills in at Syowa is distributed in GLObal Coordination of Atmospheric Electricity Measurements (GloCAEM) as both archived and real-time data in 1 min and 1 s samplings, although we terminated the whole observation in 2022.
José Tacza (Institute of Geophysics PAS, Poland): “Intecomparison of ThunderHours and Lightning-clusters at different timescales”
A thunder hour is defined as an hour during which thunder can be heard within a ~15 km radius (DiGangi, BAMS, 2022). Alternatively, thunderstorm estimation can be based on lightning clusters, where each thunderstorm is defined as an entire set of contiguous lightning grid boxes with more than one stroke, either laterally or diagonally (Ccopa et al., JASTP, 2021). In this work, we perform an intercomparison between Thunder Hours and Thunderstorms at different timescales between 2014 and 2023. Our results show a Pearson correlation coefficient greater than 0.9 for the average daily variation between Thunder Hours and Thunderstorms. Additionally, both parameters exhibit the same seasonal variation: higher values in the Northern Hemisphere summer (June-July-August) compared to the Southern Hemisphere summer (December-January-February). Spectral analysis reveals 0.5-, 1-, and ~360-day periodicities for both Thunder Hours and Thunderstorms. However, for Thunderstorms, we found a 45-day periodicity not present in Thunder Hours. Finally, an analysis of 2023 anomalies (with base period 2018-2022) shows good agreement between Thunder Hours and Thunderstorms, indicating an increase in electrical activity in the northern part of Ecuador and the northern part of the Maritime Continent, and a decrease in electrical activity in the southern part of the Maritime Continent.
Posters
Masashi Kamogawa (University of Shizuoka, Japan): “Long-term continuous observation of the atmospheric electric field at Kakioka, Japan” (poster)
In this presentation, we introduce our paper entitled “Continued atmospheric electric field measurements following cessation of the long-term water dropper potential equalizer at Kakioka, Japan” published in Geoscience Data Journal in 2023 written by M. Kamogawa et al. Japan Meteorological Agency (JMA) decided to terminate the atmospheric electric field (potential gradient) observation using using a Kelvin water dropper equalizer on February 28 of 2021 at Kakioka, Japan. The data has almost 100-year length, so that we started the field mill observation near the water dropper since February of 2021. Our new data from the field mills in this study is distributed in GLObal Coordination of Atmospheric Electricity Measurements (GloCAEM) as both archived and real-time data in 1 min and 1 s samplings, while the previous data is distributed in JMA Kakioka website.
Masashi Kamogawa (University of Shizuoka, Japan): “Local modulation of atmospheric electricity – The 2011 Fukushima nuclear power plant accident” (poster)
The 2011 M9.0 off the Pacific coast of Tohoku Earthquake caused multiple hydrogen explosions at the Fukushima Daiichi Nuclear Power Plant in mid-March, and radioactive materials were diffused and deposited after the rainfall, mainly in eastern Japan including Tokyo metropolitan area. Consequently, the atmospheric electric field measured at the Kakioka Magnetic Observatory of the Japan Meteorological Agency significantly decreased by two order magnitude from mid-March to late March 2011. After that, the radioactive materials in the atmosphere due to advection and diffusion were deposited on the ground in many parts of eastern Japan due to rainfall washout in late March, and radiation was measured near the ground for several months. In this study, we investigated the changes in atmospheric electricity including conductivity and air-earth current besides the atmospheric electric field due to the deposition of these radioactive materials, and examined how these changes affect the global electrical circuit.
Anne Neska, Mariusz Neska (Institute of Geophysics PAS, Poland): “Schumann Resonance Monitoring in Hornsund and Suwalki Stations: Data Availability 2016 – 2014 and Analysis Perspectives due to the Wavelet Transform” (poster)
The world-wide thunderstorm and lightning activity is an important element of the global electric circuit. Continous observation of the Schumann Resonance (SR) phenomenon is a proven proxy for monitoring and quantifying that world-wide lightning activity. IG PAS has operated two SR monitoring stations for 20 years, one of them in Hornsund (HRN, Svalbard). Since 2016 the second station has been situated in Suwałki (SUW, NE Poland). This nearly eight years long dataset (HRN & SUW, 2016 – 2024) has been transferred to frequency domain and stored in a special way that enables a quick access to time-dependent properties of the Schumann Resonances. We hope that this will facilitate all types of
analysis where a separation with regard to the source (chimney) region is needed. This presentation provides details on the spectral data product and examples how it can be used.
Rubén M. Romero (Mackenzie Presbyterian University, Brazil): “Neural Network-Based Prediction of the Potential Gradient: Insights from Peru, Argentina, and Brazil“ (poster)
This study presents a deep neural network-based approach for predicting the atmospheric electric field, or potential gradient (PG), in Ica (Peru), San Juan (Argentina), and São Paulo (Brazil). The model utilizes input data from 2017 to 2022, including PG measurements, meteorological parameters such as wind speed, wind direction, and irradiance, as well as aerosol data like PM10. We chose hourly data to capture seasonal variations over time. The results demonstrate a high correlation (R) in PG predictions for both long-term trends and specific dates, including fair weather (FW) and disturbed conditions (e.g., sea breezes and dust storms in Ica), although some events were underestimated by the model. Overall, the model captured the influence of these parameters on PG, enabling the simulation of FW conditions and the modeling of standard curves. In São Paulo, the effect of PM10 was modeled by simulating an aerosol-free environment, resulting in an annual curve with a peak at 16 UT, which showed a higher correlation (R) with the Carnegie curve.
Michael Rycroft (CAESAR Consultancy, UK): “Determining the time constant of the global atmospheric electric circuit through modelling and observations“ (poster)
The DC global electric circuit (GEC) distributes charge in the lower atmosphere by current flow between “generator regions” (thunderstorms and rain clouds) and “load regions” (distant conductive air),
with a timescale defined by circuit properties. In our previous works the load has only been modelled by assuming fair weather (FW) conditions, neglecting cloud. As stratiform clouds cover ∼30% of the
Earth’s surface, load resistance has been added to represent them, considered to provide semi fair weather (semi-FW) conditions. This increases the GEC timescale by 9% for stratocumulus, or 33% for
stratus at a lower level. These modelled results – the first including the semi-FW aspects – are demonstrated to be consistent with experimentally determined timescales of the real GEC, of between 7 and 12 min, derived from volcanic lightning variations associated with the May 2011 Grımsvotn eruption in Iceland. Accounting for semi-FW circumstances improves the modelled representation of the time
variations in natural global circuit. Extended results of this work are published in Rycroft et al., J. Atmos. Sol. Terr. Phys. 260, 2024. Data are available at doi:10.18150/CC4ISW
Izabela Pawlak (Institute of Geophysics PAS, Poland): “Multiannual variations of fair weather potential gradient (PG) and positive air conductivity (1965-2005) at the Geophysical Observatory in Świder, Poland“ (poster)
The subject of this work was an analysis of the variability of the fair weather potential gradient (PG) and positive air conductivity at a Geophysical Observatory in Świder (52°07’N, 21°14’E), Poland over the period 1965-2005. The aim of the analysis was to estimate the long-term variation of these components at different time scales. The calculations were made on a diurnal, seasonal, annual and multiannual (5-year) basis. The diurnal course is different depending on the season. In case of PG, during spring, summer and autumn we observe double maxima (about 7:00 and 19:00 UT), while during winter we noted a single broad maximum between 13:00 and 20:00 UT. During night and day hours (0-14 UT) only small fluctuations of air conductivity are observed. Seasonal variation is characterised by winter maximum, resulting from the anthropogenic pollution and a minimum in the summer. The conductivity reveal anticorrelation with PG showing summer maximum and winter minimum. Over 1965-2005 PG shows positive trend (~2.5 V/m per year) and conductivity presents negative trend (~-0.06 fS/m per year). The analysis of the course of annual anomalies with the reference to the 1965-2005 mean value reveals the existence of subperiods with different values and directions of anomalies for both, the PG and air conductivity data. The non-parametric U Mann-Whitney test was used to verify statistical significance in shifts between subsequent decades.
Anna Phung Thi (Space Research Centre PAS, Poland): “Utilizing LOFAR PL610 measurements for ionospheric research“ (poster)
LOFAR is an international network of 52 radio telescopes that can operate both as a single international interferometer and as individual stations. In Poland, there are three LOFAR stations, including the PL610 station in Borówiec, owned by the Space Research Centre of the Polish Academy of Sciences. Operating in the 10-240 MHz range, PL610 allows observations in the lowest frequencies accessible from Earth. While primarily used for radioastronomy, LOFAR also supports other research, such as ionospheric monitoring and space weather observations. This work reviews non-astronomical applications of LOFAR PL610 data,
focusing on phenomena like ionospheric scintillation, geomagnetic storms, and general ionospheric conditions. Ionospheric amplitude scintillation – LOFAR’s sensitivity and 10-90 MHz range enable mid-latitude studies of ionospheric scintillation. Angle of incidence scintillation – LOFAR, in single mode, observes signals from broadcast stations, revealing their origins and plasma-induced variability. Observation of Jupiter and the Sun – LOFAR’s dataset also includes measurements for Jupiter, the Sun, dynamic spectra of these sources, and S4 index measurements.
José Tacza (Institute of Geophysics PAS, Poland): “Modulation of the ground-based potential gradient by cosmic rays“ (poster)
The Global Electric Circuit (GEC) connects electrical charge separations in thunderstorms with electrical currents flowing in fair-weather regions. High-energy charged particles, such as cosmic rays, are potential factors influencing the GEC. In this study, we analyzed disturbances in the potential gradient recorded in ground-based measurements under fair-weather conditions to investigate these effects. Using superposed epoch analysis to enhance the visibility of subtle changes, we examined potential gradient data recorded between January 2010 and December 2019. Our findings show a statistically significant increase in the potential gradient following intense Forbush Decreases at the Complejo Astronómico El Leoncito (CASLEO) in Argentina (31.78° S, 2550 m a.s.l.). For Forbush Decrease identification, we used a novel classification method based on data from the Alpha Magnetic Spectrometer (AMS-02) aboard the International Space Station, rather than traditional ground-level neutron monitor data. At CASLEO, our results indicate that Forbush Decreases with a flux amplitude (A) ≤ 10% showed no significant change in the potential gradient. However, for events with A > 10%, a clear increase in the potential gradient was observed. Additionally, these more intense events demonstrated a strong correlation between the variations in Dst and Kp indices and changes in the potential gradient. On the other hand, using cross-wavelet transforms between neutron monitor data and potential gradient recordings at several stations, we found a strong common 27-day periodicity, specifically during the passage of long-lasting Co-Rotating Interaction Regions. These findings suggest that the potential gradient is modulated by cosmic ray flux.
Anna Odzimek (Institute of Geophysics PAS, Poland): “A surface air electrical conductivity model with variable aerosol content” (poster)
In Pawlak et al. (submitted to ANGEO 2024) a surface air conductivity model at fair weather conditions was created, dependent on the composition and concentrations of aerosol, and characteristic for the location of the Geophysical Observatory at Świder. Here we expand the work to illustrate how the change in the aerosol composition may affect the value of the electrical conductivity.
Last updated: 4 October 2024