Aleksandra Kolarski

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Aleksandra verified their affiliation via an institutional email.

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• PhD in technical Sciences, major: Geology (Geophysics)
• Assistant Research Professor at Institute of Physics Belgrade

Powerful solar flare events across last three solar cycles were analyzed through their geo-effectiveness, based upon remote sensing technique, using ground-based receiving system for registration of Very Low Frequency (VLF, 3-30 kHz) radio signals located at the Institute of Physics Belgrade, in Serbia, and solar soft X-ray flux (0.1-0.8 nm) data f...

Earthquakes are natural disasters that have led to the displacement of large number of people in different parts of the world. These geophysical events, often destructive in scale, lead to short- or long-term displacement from vulnerable areas. The aim of this research is to analyse the impact of earthquakes on the intensity and dynamics of human m...

Monitoring of the ionosphere enables the detection of changes that are related to numerous processes on Earth. However, space weather, primarily solar radiation, has a very significant influence on the atmospheric layers. Variations caused by these influences can be affected by some processes on Earth, which can be used to detect relevant terrestri...

Air pollution is becoming an increasingly pronounced problem globally, while Belgrade is often one of the most polluted cities in Europe. Some of the most common emitters and air pollutants are individual combustion plants, factory plants and traffic. In this paper, the variations of PM2.5 and PM10 particles were analyzed in the four-year period (f...

With a high potential for direct application in Earth and other planetary research, the innovative approach of the past few decades has promoted cooperation and productive synergies among disciplines like space exploration, atmospheric and Earth observations, laboratory and field experiments, and numerical modeling. To model atmospheres with superc...

Previously, very low frequency (VLF) ionospheric amplitude data was employed in various machine learning (ML) classification efforts (Arnaut, Kolarski, 2023; Arnaut et al., 2023; Arnaut et al., 2024), where the problem was defined as a binary classification task, determining whether a given data point in the test dataset was anomalous (e.g., solar...

Earth's lower ionospheric perturbations induced by different phenomena, such as energetic solar flare events of high class on one hand and gamma ray bursts on the other, were examined through a remote sensing approach by utilization of VLF radio signals (Very Low Frequency, 3-30 kHz) propagating globally within Earth-ionosphere waveguide. Solar X-r...

Solar activity, especially with its energetic events like solar flares and coronal mass ejections of high intensity, triggers abrupt and strong disturbances within near Earth surroundings, posing the potential hazard to numerous sophisticated technological systems both space-borne and ground-based on one hand, and putting at risk all living life on...

In this paper, we present examples of changes in VLF signals used to monitor the lower ionosphere. The mentioned changes in signal characteristics are caused by astro- and geo-phenomena. We indicate the possibility of applying machine learning in statistical analysis of these changes, which is the basis of the work on the Serbian Slovak bilateral p...

The VLF/LF Earth-ionosphere waveguide enables the remote detection of important variabilities related to environmental and solar processes. Two case studies have been considered with medium and high solar activities, both recorded by Belgrade (Serbia) and Graz (Austria) stations. This study shows the existence of electric field amplitude wave pheno...

Modern society is most often evaluated according to the presence and development stage of the space industry in a country on one hand and of the oil industry on the other. These two completely different industry branches are closely related in sense of prosperity and comfortable living style conditions of a population. However, fundamental differen...

Strong radiation has the potential to alter the structure of the Earth's atmosphere by causing more ionization. These kinds of solar activity and radiation cause sudden ionospheric disturbances (SIDs), interfere with communications from space and electrical devices on Earth, and may cause a variety of natural disasters. This work focuses on the ana...

Due to the ongoing climate change, extreme weather events globally came to attention primarily since their more frequent occurrence, especially during the last decade. Severe stormy weather conditions and interrelated electrification processes in storm-bearing clouds are well known to get into relation with Earth’s ionosphere through a global elect...

In the past few decades innovative approach is to foster collaboration and effective synergies among disciplines such as space exploration, atmospheric and Earth observations, laboratory and field experiments, and numerical modeling, with a high potential for direct application in Earth and other planetary research. Modeling various atmospheres wit...

Since solar-influenced space weather is known to be crucial for sustainable development, researchers are particularly interested in studying extreme weather occurrences, climate change, protection, and preservation (Srećković et al. 2021). Therefore, one of the most important questions is whether we can estimate the effects of solar radiation and d...

Cycling is a sustainable and healthy form of transportation that is gradually becoming the primary means of transportation over shorter distances in many countries. This paper describes the dataset used to determine the cycling characteristics of seniors in the USA and Canada. For these purposes, a specially created questionnaire was used in a surv...

Forecasting the future levels of air pollution provides valuable information that holds importance for the general public, vulnerable populations, and policymakers. High-quality data are essential for precise and reliable forecasts and investigations of air pollution. Missing observations arise when the sensors utilized for assessing air quality pa...

Machine learning (ML) methods are commonly applied in the fields of extraterrestrial physics, space science, and plasma physics. In a prior publication, an ML classification technique, the Random Forest (RF) algorithm, was utilized to automatically identify and categorize erroneous signals, including instrument errors, noisy signals, outlier data p...

Citation: Arnaut, F.; Kolarski, A.; Srećković, V.A.; Mijić, Z. Ionospheric Response on Solar Flares through Machine Learning Modeling. Abstract: Following solar flares (SF), the abrupt increase in X-radiation and EUV emission generates additional ionization and higher absorption of, e.g., electromagnetic waves in the sunlit hemisphere of the Earth'...

The process of manually checking, validating, and excluding data in an ionospheric very-low-frequency (VLF) analysis during extreme events is a labor-intensive and time-consuming task. However, this task can be automated through the utilization of machine learning (ML) classification techniques. This research paper employed the Random Forest (RF) c...

The strongest X-class solar flare (SF) event in 24th solar cycle, X9.3, occurred on 6 September 2017, accompanied by earthward-directed coronal mass ejections (CMEs). Such space weather episodes are known to cause various threats to human activities ranging from radio communication and navigation disturbances including wave blackout to producing ge...

Solar activity during solar minimum between 23 rd and 24 th solar cycle was inspected, based on solar X-ray radiation listings from Geostationary Operational Environmental Satellite (GOES) database. Periods of quiet solar conditions with low background X radiation are particularly favourable for analysis and exploration of low intensity solar flare...

The calculated photodissociation data of some small molecular ions have been reported. The cross-sections and spectral rate coefficients data have been studied using a quantum mechanical method. The plasma parameters, i.e., conditions, cover temperatures from 1000 to 20,000 K and wavelengths in the EUV and UV region. The influence of temperature an...

The lower ionosphere influences the propagation of electromagnetic (EM) waves, satellite and also terrestrial (anthropic) signals at the time of intense perturbations and disturbances. Therefore, data and modelling of the perturbed lower ionosphere are crucial in various technological areas. An analysis of the lower ionospheric response induced by...

An analysis of four solar flare X-ray irradiance effects on VLF signal amplitude and phase delay variations on the NAA/24.0 kHz signal trace during the period from 2005 September to 2006 December was carried out. Solar flare data were taken from the GOES12 satellite one-minute listings. For the VLF data, recordings at the Institute of Physics, Belg...

Comparative qualitative analysis of amplitude and phase delay variations was carried out along the trajectory of GQD/22.1 kHz and NAA/24.0 kHz VLF signal traces, propagating from Skelton (UK) and Maine (USA) toward Belgrade, induced by four isolated solar X-ray flare events occurred during the period from September 2005 to December 2006. For monito...

An analysis of D-region electron density height profile variations, induced by four isolated solar X-ray flares during period from September 2005 to December 2006, based on the amplitude and the phase delay perturbation of 22.1 kHz signal trace from Skelton (54.72 N, 2.88 W) to Belgrade (44.85 N, 20.38 E), coded GQD, was carried out. Solar flare da...

A simultaneous analysis of solar flare M2.5 class X-ray irradiance effects on VLF (Very Low Frequency) signal amplitude and phase delay variations on the 22.1 kHz (GQD transmitter) and 24.0 kHz (NAA transmitter) signals was carried out. Solar flare data were taken from GOES12 satellite one-minute listings. For VLF data recordings at the Institute o...