Zenon Nieckarz

An automatic procedure for identification of VLF detected lightning discharges in Extremely Low Frequency (ELF) measurements is presented to enable large scale analysis of global lightning and ELF propagation properties which are determined by the lower ionosphere. Using a single ELF sensor in Poland we are able to identify the majority (∼80% or more) of lightning events detected by the WWLLN VLF network. Measured in ELF magnetic impulse components, EW and NS, enable the polarity (positive or negative) determination of the WWLLN‐detected strokes, thereby complementing the WWLLN data set with polarity information. We separately analyzed the data from Africa and from the whole globe, identifying positive discharges among all identified impulses. We find that the lightning energy evaluations based on VLF measurements are only weakly correlated with lightning charge moments, which manifest themselves in the measured signal amplitudes in the ELF band. The ratio of positive discharges shows an expected significant increase for the highest amplitude impulses. We also reveal a low amplitude component dominated by positive discharges that we attribute to artifacts of the recording hardware and filtering processes.

An automatic procedure for identification of VLF detected lightning discharges in ELF measurements is presented to enable large scale analysis of global lightning and ELF propagation properties which are determined by the lower ionosphere. Using a single ELF sensor in Poland we are able to identify the majority (~80% or more) of lightning events detected by the WWLLN VLF network. Measured in ELF magnetic impulse components, EW and NS, enable the polarity (positive or negative) determination of the WWLLN-detected strokes, thereby complementing the WWLLN data set with polarity information. We separately analysed the data from Africa and from the whole globe, identifying positive discharges among all identified impulses. We find that the lightning energy evaluations based on VLF measurements are only weakly correlated with lightning charge moments, which manifest themselves in the measured signal amplitudes in the ELF band. The ratio of positive discharges shows an expected significant increase for the highest amplitude impulses. We also reveal a low amplitude component dominated by positive discharges that we attribute to artifacts of the recording hardware and filtering processes.

In this study, we present a modified running wheel system for assessing voluntary running in mice. The system employs a standard 14 cm running wheel mounted on the shaft of an incremental photoelectric rotary encoder, which generates 400 pulses per revolution and supports speeds exceeding 83 revolutions per second, well above the requirements of experiments involving voluntary wheel running in mice. Unlike commonly used devices, the proposed system enables, for the first time, a comprehensive set of measurements: quantification of the period and depth of running speed pulsations; identification of the true instantaneous maximum running speed; detection of short rest periods (∼1 s); detection of minor interactions with the wheel, such as entering or leaving without running; and determination of the dominant running direction (right/left). This approach allows more precise characterization of running behavior, including maximum and average speed, and captures additional features such as preferred running direction.

On 9 October 2022, a powerful gamma ray burst (GRB), GRB221009A, caused significant changes in the electron density of the lower ionosphere, as evidenced by VLF (3–30 kHz) radio wave observations. However, GRB221009A did not yield any observable signatures at the Schumann resonances (∼8, ∼14 Hz), which are also sensitive to the lower ionosphere. We show that the effects of GRB221009A are observable in a decrease in propagation velocity of ELF (3–1,000 Hz) lightning impulses. Analytical and numerical analysis points to an ionospheric perturbation in which the GRB increased the daytime electron density uniformly over a wide altitude range from 50 to 90 km. The GRB perturbation is markedly different from perturbations from solar flares, which significantly increase the vertical gradient of the electron density. ELF propagation velocity is shown to be a technique that can identify the altitude range of ionospheric perturbations.

This study presents, for the first time, the results of long-term measurements of radiation dose rates from cosmic and terrestrial gamma rays conducted at the Polish Polar Station Hornsund (southwestern Spitsbergen, 77°00′N, 15°33′E). The analysis focuses on the influence of meteorological factors (snow depth, temperature), cosmic conditions, and solar activity on the radiation dose rate in the Arctic region over the period 2016–2024. The mean gamma dose rate during the investigated period was 0.0990 µSv/h (median: 0.1018 µSv/h), with daily average minimum and maximum values of 0.0676 µSv/h and 0.1324 µSv/h, respectively. In comparison to the global gamma average dose rate (0.0970 µSv/h), the observed levels do not pose an additional radiation exposure risk to individuals residing at the Polish Polar Station Hornsund. However, ongoing climate change, particularly the reduction in the duration and extent of snow cover, has led to an increase in the average gamma dose rate, which may have implications for populations inhabiting polar regions.

In addition to natural electromagnetic fields (EMFs), so-called artificial electromagnetic fields exist in the biosphere, with mobile communications being one of their main sources. This study aimed to determine the impact of EMF at a frequency of 1800 MHz on the concentrations of selected hormones, sperm motility, viability, morphology and behaviors in laboratory rats. We used 28 rats divided into two equinumerous groups: control (n = 14) and experimental (n = 14). The rats in the experimental group were exposed to EMF for 12 weeks (for 10 min, four times daily); at the same time, the control specimens were kept in standard conditions. After 12 weeks, half of each group was killed, while the other half was maintained for another 4 weeks with no EMF emission. Elevated corticosterone levels and decreased thyroid-stimulating hormone levels were observed in the experimental specimens, which persisted for 2 weeks after the cessation of EMF emission. Exposure to EMF also resulted in decreased sperm motility and viability, as well as increased rat anxiety. This study shows that exposure to EMF (1800 MHz) may affect the endocrine status of the body and the behavior and reproductive functions of animals. However, hormonal disorders appear to be reversible.

The Extremely Low Frequency band (ELF: 0.03–1,000 Hz) electromagnetic signals from thunderstorm lightning discharges can propagate around the globe in the Earth‐ionosphere resonance cavity and thus be used for ionosphere monitoring. We use ELF observations of impulses detected by the World Wide Lightning Location Network (WWLLN) to investigate ELF propagation velocity and arrival azimuth under diurnal changes over 2 days in September 2023. Also, temporary effects of solar flares' ionizing fluxes are monitored, leading to increase of the ELF signal propagation speed in proportion to the X‐ray flux intensity. We present a simple method for automatic and large‐scale analysis, utilizing data from two registration systems (our ELF reciever and WWLLN) and enabling easy evaluation of changes in wave propagation speed. Comparative analysis of WWLLN identified impulses generated in Africa and America reveals varying effects of signal refraction, with increased azimuth changes for signals propagating across the ionospheric ionization gradients associated with the day/night terminator. The method has a potential to become a standard tool for the analysis and monitoring of the lower layers of the ionosphere.

Solar flares have profound impacts on the lower ionosphere and long‐distance radio propagation. Extremely low frequency (ELF: 3–3,000 Hz) waves are challenging to observe and experience unique interactions with the lower ionosphere. The primary natural sources of ELF waves are thunderstorm lightnings across the globe. Using a newly developed azimuth determination technique and improved observation hardware we show that ELF attenuation in the Earth‐Ionosphere spherical cavity decreases and propagation velocity increases under the influence of an M‐class solar flare. Using a two‐parameter model of the lower ionosphere, the observations are shown to be consistent with increased electron density and sharper gradients in the D‐region resulting from X‐ray radiation. The sharper electron density gradient is primarily responsible for the propagation velocity increase, suggesting a unique capability that ELF observations can bring to global remote sensing of the lower ionosphere under space weather perturbations.

We perform azimuth time tracking of multiple thunderstorm centers on the globe, which are sources of extremely low frequency (ELF) electromagnetic waves propagating in the spherical Earth‐ionosphere cavity. For observations made in September 2023 we identify azimuths of numerous global emission centers using our data sampled at 3 kHz at the Hylaty station in Poland. We confirm significant and relatively regular thunderstorm azimuth variation during the solar terminator passage over the observation site. The magnitude and duration of the azimuth deviations depend on the observed azimuths but are also varying between successive days and changing detailed thunderstorm activity patterns. The measured maximum positive (preferentially at the sunrise time) and negative (preferentially at the sunset time) azimuth deviations reach even above 20 for waves propagating close to the terminator. We discovered also particular composite deviation structures, with the negative azimuth deviation directly preceding a larger positive one, sometimes occurring near the morning terminator passage 100 km above the surface. It is possibly the first detection of the ELF equivalent of the “greyline” transmission known in the HF radio propagation. At azimuths distant from the terminator one can observe decreasing of the regular deviation magnitude and occasionally lower magnitude deviations with opposite sign. The variations between successive days are expected to result from varying thunderstorm activity on Earth as well variability of ionospheric parameters, in particular of ionization gradients and nonuniformities occurring along the terminator. We postulate that the observed deviations result from a signal refraction at the varying ionospheric gradients.

The Extremely Low Frequency band (ELF: 0.03 – 1000 Hz) electromagnetic signals from thunderstorm lightning discharges can propagate around the globe in the Earth-ionosphere resonance cavity and thus be used for ionosphere monitoring. We use ELF observations of the World Wide Lightning Location Network (WWLLN) impulses to examine ELF propagation velocity and arrival azimuth under diurnal changes in two days of September 20th and 21st, 2023. Also temporary effects of solar flares’ ionizing fluxes are monitored, leading to increasing the ELF signal propagation speed modulated by the X-ray flux intensity. We present for the first time a simple method for automatic and large-scale analysis, utilizing data from two registration systems (ELF and WWLLN) and enabling easy evaluation of changes in wave propagation speed. The compared samples of WWLLN impulses generated in selected azimuth and distance sectors for Africa and America reveal varying effects of signal refraction, with increased azimuth changes for signals propagating across the ionospheric ionization gradients. The method has a potential to become a standard tool for the analysis and monitoring of the lower layers of the ionosphere.