Journal of Atmospheric and Solar-Terrestrial Physics最新文献

We analyzed intense geomagnetically induced currents (GICs) recorded during a complex space weather event observed on 23–24 April 2023. Two geomagnetic storms characterized by SYM/H intensities of −179 nT and −233 nT were caused by southward interplanetary magnetic field (IMF) Bz component of −25 nT in the sheath fields, and −33 nT in the magnetic cloud (MC) fields, respectively. GIC observations were divided into two local time sectors: nighttime (1700–2400 UT on 23 April) GICs observed during the interplanetary sheath magnetic storm, and morning sector (0200–0700 UT on 24 April) GICs observed during the MC magnetic storm. By using the direct measurements of GICs on several substations of Karelian-Kola power line (located in the north-west portion of Russia) and gas pipeline station near Mäntsälä (south of Finland), we managed to trace the meridional profile of GIC increases at different latitudes. It was shown that the night sector GIC intensifications (∼18–42 A) occurred in accordance with poleward expansion of the westward electrojet during a substorm. On the other hand, the intense morning sector GICs (∼12–46 A) were caused by Ps 6 magnetic pulsations. In addition, a strong local morning GIC (∼44 A) was associated with a local substorm-like disturbance caused by a high-density solar wind structure, possibly a coronal loop portion of an interplanetary coronal mass ejection.

Accurate forecasting of heavy rainfalls and understanding of their dynamics are important to minimize the damage caused by them in the Democratic People's Republic of Korea (DPR Korea). This study is conducted on a heavy rainfall event (452 mm) on 9–10 August 2020 over Pankyo region located on the midlands of the Korean peninsula. To verify the proper configuration of convection-permitting simulations, sensitivity experiments were performed with five microphysical schemes (Lin, Goddard, Thompson, Morrison and WDM6) of the Weather Research and Forecasting (WRF) model. The results suggested that all high-resolution simulations reflect the main characteristics of observed precipitation pattern well, but the location and intensity of maximum precipitation from scheme to scheme. Among the considered all the microphysics, the Lin scheme showed the best agreement with observed precipitation. Results also showed that the Lin scheme reproduced the vertical distribution and time variation of several hydrometeors, as well as dynamic and thermodynamic parameters associated with heavy rainfall well. These outcomes suggest that the suitable selection of microphysics schemes with WRF model is important to predict and understand heavy rainfall events over the DPR Korea.

Ball lightning sometimes passes through closed glass windows, usually without damage but occasionally causing characteristic damage in the shape of a circular hole. We review some of these relatively rare cases, present a probable new case, and elucidate a process that accounts for the type of damage typically seen. The process requires volume rather than surface heating of the glass, and this requirement is not met by most current theories of ball lightning, except for one that involves new physics.

In order to ensure the operation of wireless communication and radar equipment during haze events, it is necessary to study the quantitative prediction of the attenuation coefficient of Electromagnetic wave (α) during haze events. The results of the dimensional analysis show that particle humidity (H_p) and particle charge-to-mass ratio (Q_m) are two important parameters that affect the propagation of electromagnetic waves. At the micro level, the influence of two parameters is introduced into the electromagnetic wave attenuation model through the core-shell structure. The results show that the H_p and Q_m will increasing α. Due to it being difficult to obtain the physical parameters in the micro-scale model by experimental methods. Therefore, this article analyzes the experimental data of Zhang et al. (2020b) and finds out that the change of α can be scaled by H_p, and Q_m mainly affects the slope term of the linear change of α with H_p. Based on these findings, an empirical model of α considering H_p and Q_m was proposed. The results show that the influence of H_p and Q_m during haze events with high humidity cannot be ignored. And, the relative humidity has the largest contribution to α, the particle charging has the second place, and the primary release of particulate matter has the smallest contribution. The advantage of this model is that it is not only simple in form and easy to apply, but also that the input required and model parameters can be measured with experimental methods.

In this study, we analysed the influence of prevailing atmospheric oscillations at different scales on tropical cyclones (TC) movement over the Bay of Bengal. Composite analysis of dynamic and thermodynamic variables are investigated with and without TC during pre-monsoon and post-monsoon seasons. The composite features analysed at multi-scales clearly suggests that pre-monsoon TC track predominantly determine by a net interaction of mean climatology environment (CLM) and anomalies associated with sub-seasonal oscillations. Whereas, during post-monsoon CLM is critical in governing the storm track. Similarly, the study also signifies that CLM and sub-seasonal anomalies jointly provide guiding effect for various TC paths.

This article delves into the seasonal variation of solar radiation patterns across Nigeria’s four geo-political zones, exploring their complex, scale-dependent behaviors. By employing chaotic quantifiers, the study characterizes irregular and self-similar patterns, enhancing our understanding of solar radiation variability and heterogeneity. The research uniquely fits meteorological parameters onto a global solar radiation model and focuses on the underexplored nonlinear aspects within tropical regions, specifically in the Nigerian context. Utilizing daily data from ERA INTERIM satellite archives for representative stations, the study employs nonlinear time series analysis methods like recurrence plots, recurrence qualitative analysis, and multifractal spectral analysis to comprehensively explore the unpredictable behaviors observed. The quantifier spectrums play a key role in revealing intricate scaling behaviors and correlation structures among environmental variables, shedding light on patterns often concealed by conventional statistical methods. For instance, we found that solar radiation variability in the northern region increases more significantly during the dry season compared to the wet season, unlike in the southern region. Additionally, the multifractal spectral analysis revealed a higher degree of complexity in solar radiation patterns during transition periods between seasons. The findings reveal a low recurrence quantitative analysis, long right tail, and truncations at both ends of the spectrum. This suggests instability in solar radiation across different seasons and locations. Nonetheless, the results also demonstrate that solar radiation is consistently available throughout the year, which is typical of tropical regions.

Long-term series of solar irradiation measured at ground level are not available in the old times. However, long-term series of actinometric degree data obtained by using the Arago-Davy instrument have been recorded in the second half of the 19th century in several locations of the world. We have developed recently a method to estimate global solar irradiance on horizontal surface from actinometric degree data (doi.org/10.1007/s00704-023-04485-2). This opens a way of finding proxy information about the incident solar irradiance on various areas of the globe before the 20th century. Hourly actinometric degree data for the years 1892–1903 are available at the Filaret Observatory (Bucharest, Romania, South-Eastern Europe). The observed series have a systematic decreasing tendency, which has been removed by using a correction procedure. The proposed method is used here to evaluate solar global irradiance at Filaret Observatory. Solar irradiance data provided by the Twentieth Century Reanalysis Project version 3 (20CRv3) are used as a reference. The expected hourly and daily average solar irradiance values show reasonable qualitative consistency with the 20CRv3 data. This consistency is notably stronger during the warmer months from April to September. Much better agreement is found for the monthly averaged solar global irradiance values. At this level, the proposed method and the procedure of the 20CRv3 project seem to validate each other.

This study investigates the occurrence of chaotic pulse trains (CPTs) and regular pulse trains (RPTs) in tropical positive cloud-to-ground (CG) lightning flashes. These flashes are categorized into four types based on the initial polarity of the initial breakdown (IB) pulses and their relationship to the first return stroke (RS). A total of 71 positive CG flashes from five thunderstorm events were analyzed. The analysis reveals instances of CPTs and RPTs both before and after the first positive RS, along with the occurrence of mixed polarities in RPTs. Variations in IB pulse polarities and the presence of CPTs and RPTs before the first positive RS were observed, contrasting with previous findings in negative CG flashes. All positive CG flashes have been detected when cloud top height occurrences were between 12 and 18 km. In contrast, for negative CG flashes with CPTs and RPTs the cloud top height occurrences were between 5 and 12 km. It is interesting that CPTs and RPTs can be detected during IB process of positive CG flashes at relatively high altitude in the thundercloud. Perhaps due to low pressure at higher altitudes in the cloud, electrical process associated with CPTs and RPTs are easily discharged before the occurrence first positive return stroke. The altitudes of cloud top heights for the inverse polarity of IB pulses were located between 16 and 18 km. This research enhances the understanding of positive CG lightning initiation process and their relationship with CPTs and RPTs, as well as the occurrence of recoil leaders.

Understanding the variable behavior of the IDL/Es system contributes significantly to our ability in characterizing and modeling the critical ionospheric dynamics across the globe. In this work we aim to improve the understanding of the IDL/Es system by analyzing the diurnal and seasonal variations in the altitude descent with reference to local time of the day, season, and solar activity. We apply the well-known height-time-intensity analysis method on measurements obtained from the Sharjah ionosonde station, located at the Arabian Peninsula (Sharjah: 25.28°N, 55.46°E) near the northern crest of the equatorial ionization anomaly. The measurements cover three years of the increasing phase of the solar cycle 25 from 2020 to 2022. Considering an oversimplified wind system based on windshear theory, we attempt to establish a relationship between IDL/Es periodicities with diurnal, semidiurnal, and terdiurnal tides without digging into the underlying mechanism. Results suggest a strong relation between semidiurnal and terdiurnal tides and the formation and transport of the IDL, particularly impacting lower E-region and sporadic-E layers during the afternoon and nighttime hours. The results of manual scaling of over eleven thousand ionograms is presented to quantify the behavior of the IDL/Es system's transport. Additionally, a connection between solar activity, descent rate, and initial descending height, with semidiurnal patterns consistently present across seasons and solar activity has been discussed. For different frequency bins used in this work, e.g. 3 MHz, 4 MHz, and 5 MHz, seasonal variations significantly influence descent patterns.

Atmospheric lightning is a dominant weather related disaster which requires continuous monitoring efforts. While the world wide lightning location network (WWLLN) measures the very low frequency (VLF) signals emanating from the lightning, other regional networks, such as Lightning Detection Sensor Network (LDSN) use the broad band radio frequency signals. Present investigation compares the cloud-to-ground (CG) lightning occurrences recorded by the WWLLN and LDSN during 02 October – October 09, 2022 over India. Results show that though the WWLLN monitored the CG lightning occurrences about 20% lesser than the LDSN, spatial distribution of the occurrences and trends were in very good agreement.