Measuring global signals in the potential gradient at high latitude sites

Previous research has shown that the study of the global electrical circuit can be relevant to climate change studies, and this can be done through measurements of the potential gradient near the surface in fair weather conditions. However, potential gradient measurements can be highly variable due to different local effects (e.g., pollution, convective processes). In order to try to minimize these effects, potential gradient measurements can be performed at remote locations where anthropogenic influences are small. In this work we present potential gradient measurements from five stations at high latitudes in the Southern and Northern Hemisphere. This is the first description of new datasets from Halley, Antarctica; and Sodankyla, Finland. The effect of the polar cap ionospheric potential can be significant at some polar stations and detailed analysis performed here demonstrates a negligible effect on the surface potential gradient at Halley and Sodankyla. New criteria for determination of fair weather conditions at snow covered sites is also reported, demonstrating that wind speeds as low as 3m/s can loft snow particles, and that the fetch of the measurement site is an important factor in determining this threshold wind speed. Daily and seasonal analysis of the potential gradient in fair weather conditions shows great agreement with the “universal” Carnegie curve of the global electric circuit, particularly at Halley. This demonstrates that high latitude sites, at which the magnetic and solar influences are often present, can also provide globally representative measurement sites for study of the global electric circuit

Challenges in coupling atmospheric electricity with biological systems

The atmosphere is host to a complex electric environment, ranging from a global electric circuit generating fluctuating atmospheric electric fields to local lightning strikes and ions. While research on interactions of organisms with their electrical environment is deeply rooted in the aquatic environment, it has hitherto been confined to interactions with local electrical phenomena and organismal perception of electric fields. However, there is emerging evidence of coupling between large- and small-scale atmospheric electrical phenomena and various biological processes in terrestrial environments that even appear to be tied to continental waters. Here, we synthesize our current understanding of this connectivity, discussing how atmospheric electricity can affect various levels of biological organization across multiple ecosystems. We identify opportunities for research, highlighting its complexity and interdisciplinary nature and draw attention to both conceptual and technical challenges lying ahead of our future understanding of the relationship between atmospheric electricity and the organization and functioning of biological systems

SuperDARN in Poland : opportunity for atmospheric science research

SuperDARN (Super Dual Auroral Radar Network) jest światową siecią radarów koherentnego rozpraszania w paśmie wysokich częstotliwości HF (High Frequency) do badań górnych warstw atmosfery, mezosfery, jonosfery, termosfery oraz ich sprzężenia z magnetosferą i wiatrem słonecznym. Do głównych tematów badawczych SuperDARN z dziedziny fizyki atmosfery należą echa mezosferyczne, fale planetarne i związane z nimi przemieszczające się zaburzenia jonosferyczne oraz inne przejawy oddziaływania atmosfery neutralnej ze zjonizowaną. W artykule przedstawiamy perspektywy dla rozwoju badań atmosfery z użyciem radarów SuperDARN w kraju, ze szczególnym uwzględnieniem badań z dziedziny elektryczności atmosferycznej.SuperDARN (Super Dual Auroral Radar Network) is a global network of coherent scatter radars in the HF (High Frequency) band for studying the upper atmosphere, mesosphere, ionosphere, thermosphere and their coupling with the magnetosphere and solar wind. SuperDARN research topics in the field of atmospheric physics include mesospheric echoes, planetary waves and associated travelling ionospheric disturbances, and other manifestations of the interaction of neutral and ionised atmosphere. In the article we present prospects for the development of atmospheric research in Poland using SuperDARN radars, with particular emphasis on research studies in the field of atmospheric electricity

Polar Regions in the Earth’s Global Atmospheric Electric Circuit Research

W artykule przedstawiono główne cechy ziemskich obszarów polarnych, Arktyki i Antarktyki, z punktu widzenia ich przynależności do globalnego atmosferycznego obwodu elektrycznego Ziemi oraz połączenia z układem prądów elektrycznych magnetosfery Ziemi. Omówiono lokalizację i chronologię obserwacji i badań elektryczności atmosfery w regionach polarnych do roku 2015, których znacząca liczba miała miejsce w czasie dużych przedsięwzięć geofizycznych, takich jak Międzynarodowe Lata Polarne i Międzynarodowy Rok Geofizyczny. Osobno dokonano przeglądu najważniejszych wyników badań elektryczności atmosfery w polskich stacjach polarnych – im. S. Sie¬dleckiego w Hornsundzie na Spitsbergenie w Arktyce i im. H. Arctowskiego na Wyspie Króla Jerzego w Antarktyce. Na zakończenie przedstawiono możliwe kierunki rozwoju badań elektryczności atmosfery z wykorzystaniem polskich stacji polarnych oraz pola interdyscyplinarnej współpracy naukowej.The article presents the main features of the polar regions, Arctic and Antarctic, from the point of view of the Earth’s global atmospheric electric circuit and its connection to the electric current system of the Earth’s magnetosphere. The chronology of observations and research studies of atmospheric electricity in polar regions up to 2015 is presented, including main geophysical events such as International Polar Years and International Geophysical Year. Research studies on atmospheric electricity based on measurements at Polish polar stations: S. Siedlecki Polar Station in Hornsund, Spitsbergen, and H. Arctowski Antarctic Station on King George Island, have been reviewed separately. Article concludes with the possible directions of development of atmospheric electricity research using Polish polar stations and potential fields of interdisciplinary scientific cooperation

SuperDARN in Poland – a perspective

SuperDARN (Super Dual Auroral Radar Network) jest światową siecią radarów do badania górnych warstw atmosfery, jonosfery i ich sprzężenia z magnetosferą i wiatrem słonecznym (Greenwald i in. 1995; Chisham i in. 2007; Lester 2008, 2013, Nishitani i in. 2019). W artykule przybliżamy szczegóły techniczne, tematy badawcze i publikacje związane z działalnością SuperDARN oraz korzyści płynące z polskiego w nim udziału, który mógłby wzmocnić badania krajowe, jak i współpracę międzynarodową oraz otworzyć nowe tematy badawcze. Zanim to będzie możliwe, należy rozwiązać kilka technicznych kwestii, których tło i perspektywy nakreślamy.SuperDARN (Super Dual Auroral Radar Network) is a global radar network for studying the upper atmosphere, ionosphere, thermosphere and mesosphere and their coupling with the magnetosphere and solar wind (Greenwald et al. 1995; Chisham et al. 2007; Lester 2008, 2013, Nishitani et al. 2019). In the article we bring closer to national readers the SuperDARN network through describing its technical details, projects and publications. In addition to strengthening present research Polish participation in SuperDARN could result in development of new topics in national research and in international cooperation. Before it is possible, several technical issues should be solved, the background and perspectives of which we outline in the article

Determining the time constant of the global atmospheric electric circuit through modelling and observations

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. Previously, 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. Including mutual capacitance between the outer charged layer and an electrode representing stratocumulus clouds increases the timescale by 35 %, to 8.6 minutes. 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 minutes, derived from volcanic lightning variations associated with the May 2011 Grímsvötn eruption in Iceland. Accounting for semi-FW circumstances improves the modelled representation of the natural global circuit. Further, the GEC timescale is comparable with cloud droplet charging timescales in the updrafts of extensive layer clouds, suggesting its possible relevance to the microphysical behaviour of stratiform (layer) clouds in the climate system

Cloud‐to‐ground lightning dipole moment from simultaneous observations by ELF receiver and combined direction finding and time‐of‐arrival lightning detection system

We present a new method of automatic detection of ELF impulses related to cloud‐to‐ground lightning at distances 1–2 Mm from a broadband ELF receiver and also we present a new numerical automated technique for calculating the lightning dipole moment. We have performed the detection for two known data sets of lightning flashes detected by the French lightning detection network Meteorage in southwest Europe over two 48 h periods 28–29 July and 6–7 September 2005. The number of flashes identified in the ELF data compared to the number of flashes detected by Meteorage reach 10–25% when little local activity close to the ELF station is present. The local thunderstorm activity worsens the detection of lightning from larger distances and the efficiency of identification of ELF impulses as lightning can decrease to a few percent. By combining the information on the location of the lightning flashes from Meteorage with the ELF data, lightning dipole moments can be calculated. Our results suggest the dipole moment is linearly correlated with the lightning peak current (p ≃ 7.5 Imax) but the dispersion of the dipole moment for a given peak current is significant. One of the reasons of such dispersion is the contribution of the lightning continuing current to the ELF signal

AC and DC global electric circuit properties and the height profile of atmospheric conductivity

An apparent discrepancy is pointed out - at all heights, and by up to an order of magnitude - between the height profiles of atmospheric conductivity derived at AC using ELF propagation studies, especially from information on Schumann resonance of the Earth-ionosphere cavity, and using a model of the DC global atmospheric electric circuit. This serious issue is resolved by creating a hybrid profile of these two mid-latitude profiles, the first of which refers to conditions by day and the second by night. This hybrid profile is thus a first order attempt to represent globally averaged conditions. Close to the Earth’s surface, where the resistance of the atmosphere is largest, the properties of the DC global model exert the greatest influence, whereas in the middle atmosphere, at heights between 40 and 100 km, full wave computations show that the AC results are the more crucial. The globally averaged hybrid profile presented here has some limitations, and the physical reasons for these are addressed. They are due to the presence of aerosol particles of ice and/or of meteoric material which reduce the ionospheric D-region conductivity by an order of magnitude over only ~2 km of height, thereby causing ledges of ionisation. In the context of the globally averaged profile, published observations of the ionospheric effects of the giant gamma-ray flare from SGR 1806-20 (a neutron star having an enormously large magnetic field) occurring at 21:30 U.T. on December 27, 2004, are briefly discussed