Journal of Atmospheric and Solar-Terrestrial Physics最新文献

{"title":"Possible ionospheric effects of two major earth quakes in Papua New Guinea","authors":"B. Felix Pereira,&nbsp;Jessy Sekere","doi":"10.1016/j.jastp.2025.106457","DOIUrl":"10.1016/j.jastp.2025.106457","url":null,"abstract":"<div><div>Pre-seismic ionospheric F2 layer instabilities have been studied which could help in predicting earthquakes. Two major earthquakes in the western province of Papua New Guinea, one in Sissano in 1998 of magnitude 7.1 and the other in Aitape in 2002 of magnitude 6.7 were analyzed. An analysis of the perturbations in the electron content up to the ionospheric F₂ layer peak and F2 layer peak height (h_mF2) variations during earthquake time has been done using published ionosonde data. A decrease in peak electron density ranging from 20 to 30% was observed within 10 days during pre-seismic as well as post-seismic periods during both earthquakes. On these days, an increase in the height of the peak electron density was also observed. This could be because during seismic periods, a large amount of radon gas is emitted during earthquake preparation time, which ionize neutral atoms and molecules and the ions raise to ionospheric heights by electric fields created and produce ionospheric fluctuations. This helps in predicting the earthquake in advance.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106457"},"PeriodicalIF":1.8,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of variability in chlorophyll-a and covariates in East/Japan sea: New insights from the ARIMAX model and wavelet coherence","authors":"Salman Tariq ,&nbsp;Ayesha Mariam ,&nbsp;Muhammad Khan","doi":"10.1016/j.jastp.2025.106450","DOIUrl":"10.1016/j.jastp.2025.106450","url":null,"abstract":"<div><div>The atmospheric aerosols and the concentration of Chlorophyll-a (Chl-a) in coastal and clear water is an important research field that involves the multiple aspects of environmental degradation and analyzing the health of the marine environment. Therefore, ocean color satellite remote sensing is an efficient way to observe and monitor the aquatic system and the ocean at various spatial, temporal, and spectral scales. Therefore, this study analyzes the spatiotemporal dynamic variability in various ocean color variables, i.e., Sea surface temperature (SST), Aerosol optical depth (AOD), Black carbon dry deposition (BCD), Calcite concentration (CC), Ocean Rain (O-Rain), and Sensible heat flux (SHF) over the East/Japan Sea (EJS) from 2002 to 2023. Furthermore, we used the ARIMAX model and Wavelet coherence (WTC) analysis for analyzing the variability of these oceanic parameters with Chl-a. The spatial concentration of Chl-a is observed high over the northern EJS, particularly around 141ᵒ E, 50ᵒ N, southwestern EJS, and around 141ᵒ E, 43ᵒ N (along the Japanese coast). Furthermore, the western EJS also showed the highest concentration of Chl-a than the eastern EJS. Generally, the mean concentration of Chl-a in EJS increasing at the rate of 0.4 mg m⁻³/yr showed the maximum value of 0.8 mg m⁻³ during the study period. Moreover, the ARIMAX models elucidated a direct coupling of the Chl-a with O-Rain and BCD while it showed an inverse and statistically significant association with AOD, SST, CC, and SHF. The WTC analysis indicated a strong association of above 0.8 of Chl-a with all selected variables between a scale period of 8–16. Among all selected variables, CC, SHF, and BCD show a stronger association with Chl-a over the EJS. Therefore, this study will help the policymakers in identifying the major hotspots of Chl-a in EJS to analyze the water quality and health of the marine environment.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106450"},"PeriodicalIF":1.8,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of VLF signal during partial solar eclipse of 25 October 2022","authors":"Ramesh Krishna B,&nbsp;P. Chaithra,&nbsp;Kamsali Nagaraja","doi":"10.1016/j.jastp.2025.106458","DOIUrl":"10.1016/j.jastp.2025.106458","url":null,"abstract":"<div><div>The partial solar eclipse on October 25, 2022, had an observable effect on very low frequency (VLF) signals along the transmission paths of GQD (22.10 kHz) and DHO (23.40 kHz). Signal variations were analyzed for October 22–28, 2022, with a focus on amplitude changes during the greatest eclipse (GE) phase. During the partial solar eclipse, the GQD and DHO signal paths experienced 11% and 14% obstructions, respectively. On the day of the eclipse, the amplitude of the GQD is 0.83 dB lower compared to pre-days and 0.11 dB greater than post-days, and for DHO it is increased by 0.26 dB and 0.57 dB for pre- and post-eclipse days at the time of GE. Observations revealed stronger solar flare signatures in GQD signal compared to the DHO signal, attributed to differences in ionospheric conditions along the propagation paths. A pronounced rise in amplitude before and after the GE phase was observed in the GQD signal, linked to solar flare activity. Additionally, the analysis confirmed that the PSE was the primary driver of increased VLF signal amplitude during the GE phase along the DHO path. The results emphasize the significant impact of partial solar eclipses on ionospheric dynamics and VLF signal propagation.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106458"},"PeriodicalIF":1.8,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143418889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the retrieval of particle size information of noctilucent clouds from optical remote sensing measurements","authors":"Christian von Savigny","doi":"10.1016/j.jastp.2025.106447","DOIUrl":"10.1016/j.jastp.2025.106447","url":null,"abstract":"<div><div>Noctilucent clouds (NLCs) are optically thin ice clouds occurring near the polar mesopause in the summer hemisphere. Our understanding of the particle size of NLCs is to a large extent based on optical measurements in different observation geometries and optical NLC particle size retrievals are always based on a priori assumptions on the shape of the particle size distribution. The actual shape of the particle size distribution is generally not well known and can be assumed to be highly variable. In addition, the scattering cross section of NLC particles depends strongly on particle size. This leads to effects that have until now not been considered properly in the literature, i.e. if the assumed shape of the particle size distribution differs from the actual one, NLC size retrievals based on different measurement techniques will be associated with different biases. These differences can be quite substantial, for the retrieved particle number density in particular. In this study we carry out NLC particle size retrievals based on simplified synthetic forward simulations for the following observation techniques: satellite occultation, satellite limb-scatter, ground-based lidar and satellite nadir measurements. For the forward simulations we assume a bi-modal particle size distribution, while for the size retrieval a mono-modal distribution is assumed — which is typically the case in the literature. We assume both normal and log-normal particle size distributions, but the main results of this study are independent of the specific assumption on the shape of particle size distribution. We find that even for small deviations from the assumed shape of the particle size distribution, relatively large differences in retrieved size estimates occur between the different observation geometries considered. The retrieved median radii can differ by up to a factor of 2, while retrieved particle number densities can differ by more than a factor of 10 between the different observation geometries. These results need to be considered when comparing NLC size retrievals from different optical techniques.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106447"},"PeriodicalIF":1.8,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ionospheric disturbances over Ukraine through the eyes of standalone GNSS receiver","authors":"Sayak Ray ,&nbsp;Batakrushna Senapati ,&nbsp;Bhaskar Kundu ,&nbsp;M. Santosh","doi":"10.1016/j.jastp.2025.106451","DOIUrl":"10.1016/j.jastp.2025.106451","url":null,"abstract":"<div><div>The atmospheric waves generated from large-scale natural phenomena such as earthquakes, volcanoes, and anthropogenic explosions propagate upward to the upper atmosphere and cause perturbations in the ionosphere. In the present study, we investigate the ionospheric perturbations in terms of total electron content (TEC) signatures induced by the missile/airstrikes over the Ukraine region during the ongoing Russian-Ukrainian conflict, which has been captured through a standalone ground-based Global Navigation Satellite System (GNSS) receiver. We observed an ionospheric electron content change of ∼0.1–0.3 TECU caused by the acoustic wave generated from the missile/air strikes. We also noticed a strong directivity of the ionospheric disturbances over Ukraine, with maximum ionospheric disturbances in the south direction from the epicenter of the events. Further, the ionospheric disturbance's peak-to-peak amplitude was 1.5% of the background electrons, slightly less than the magnitude of volcanic eruptions in the Islands of Japan.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"268 ","pages":"Article 106451"},"PeriodicalIF":1.8,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143270165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Is heating of ions by Alfvén waves via nonresonant interactions applicable in the Earth’s magnetosphere?","authors":"I.A. Barghouthi,&nbsp;W.T. Rabai","doi":"10.1016/j.jastp.2024.106413","DOIUrl":"10.1016/j.jastp.2024.106413","url":null,"abstract":"<div><div>Heating of ions in Earth’s magnetosphere by enhanced Alfv<span><math><mover><mrow><mi>e</mi></mrow><mrow><mo>́</mo></mrow></mover></math></span>n waves below resonance frequency (nonresonant heating) has been presented in many studies, among these is the study of Wang et al. (2006) in which they stated that in any region in space with low beta plasma, this heating process, i.e. nonresonant ion heating is applicable and effective. In this paper we stress on the inapplicability of this type of heating in the Earth’s magnetosphere. We present; (1) a data set that provides a strong proof that the theory presented by Wang et al. (2006) is not applicable in this region of space (i.e. Earth’s magnetosphere), (2) in addition, we plot altitude profiles for parallel, perpendicular, and total temperatures for hydrogen ions in cusp and central polar cap regions by evaluating observed magnetic activity and Alfv<span><math><mover><mrow><mi>e</mi></mrow><mrow><mo>́</mo></mrow></mover></math></span>n waves into Wang et al. (2006) theory, we find the changes in the altitude behavior in ion temperature profiles are very small, (3) also, we compare between Monte Carlo simulations results of ion temperatures obtained by using Barghouthi model (this model includes the effects of gravity, polarization electric field, divergence geomagnetic field, centrifugal acceleration, resonant ion heating, and with and without nonresonant ion heating effect) in cusp and central polar cap regions with appropriate boundary conditions (Barghouthi et al., 2008), both simulation results of ion temperatures are almost the same. Therefore, we report on the nonresonant ion heating process in central polar cap and cusp regions is not significant.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106413"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate time series variability analysis of Islamabad Capital Territory using fractal dimension and Hurst exponent methods","authors":"Ali Khan ,&nbsp;Shahid Hussain ,&nbsp;Ahmed Bakhet ,&nbsp;Afshan Anwer ,&nbsp;S.M. Murshid Raza ,&nbsp;Sajjad Ali ,&nbsp;Mohammed Zakarya","doi":"10.1016/j.jastp.2024.106406","DOIUrl":"10.1016/j.jastp.2024.106406","url":null,"abstract":"<div><div>This study is an attempt to examine variability of climatic parameters at local scale, Islamabad Capital Territory (ICT). Climate change can affect temperature trends and precipitation patterns, horticultural activity, agricultural productivity, underground water level, portable water availability, and infrastructure.To assess the impact of climate change of Islamabad Capital Territory, the data of precipitation, minimum and maximum temperatures were obtained for the period from 1983 to 2022 from Pakistan Metrological Department (PMD). Fractal dimension <em>D</em> and Hurt exponent <em>H</em> methods were employed to estimate the monthly maximum and minimum temperatures, and precipitation of the study area. The data was portioned into 4 subsets. Rescaled range analysis method was applied on the datasets to compute values of Hurst exponent and fractal dimension. The results obtained show Brownian random and persistent tendencies, correspondingly. On the other hand, the period from 2013 to 2022 shows anti-persistent trend for H and random trend during (2013–2022) for D, respectively. The time series showing persistent results contain the long-term memory. When a time series shows random Brownian behaviour, thenthere will be no any extended long-term memory. Rescaled range analysis (<em>R/S</em>)method was employed to compute fractal dimensions show consistent outcomes, reveal small fluctuation in the local behaviour of minimum temperatures.Whereas, Hurst exponent values of maximum temperatures show random behavior i.e. there exists no correlation. The Hurst exponents computed confirm persistent results for precipitation pattern. Likewise, the computed values of fractal dimensions also show persistent results. Thus, the precipitation pattern shows cyclic behaviour, i.e. the precipitation time series retain long-run memory. Finally, from the persistent behavior of time series, one would infer that there will bean extended time effect on the local precipitation pattern. Python software was used to perform computations.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106406"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical investigations on the reactions of CH3CH2NCH3 radicals in the presence of NO, NO2 and O2","authors":"Fei Liu ,&nbsp;Chenggang Lu ,&nbsp;Yizhen Tang ,&nbsp;Yaru Pan","doi":"10.1016/j.jastp.2025.106420","DOIUrl":"10.1016/j.jastp.2025.106420","url":null,"abstract":"<div><div>The reactions of CH₃CH₂NCH₃ amino radicals in the presence of NO, NO₂ and O₂ were investigated by quantum chemistry methods. It was found that CH₃CH₂N(CH₃)NO, CH₃CH₂N(CH₃)NO₂ and CH₃CH₂N(CH₃)ONO can be formed dominantly when CH₃CH₂NCH₃ reacts with NO and NO₂, while CH₃CH=NCH₃ and CH₃CH₂N=CH₂ will be feasible when CH₃CH₂NCH₃ is in the presence of oxygen. Time dependent density functional theory (TDDFT) calculation shows that CH₃CH₂N(CH₃)NO and CH₃CH₂N(CH₃)ONO can photolyze under the sunlight, while CH₃CH₂N(CH₃)NO₂ cannot undergo photolysis in the daytime. Comparisons among the reactions of (CH₃)₂N, (CH₃CH₂)₂N and CH₃CH₂NCH₃ with NO, NO₂ and O₂ indicate that the asymmetric substituted alkyl groups will play a notable role in the formation of stable products.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106420"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The vertically time-dependent aerosol effect on marine water clouds","authors":"Hui Lu ,&nbsp;Hui Zhao ,&nbsp;Kanike Raghavendra Kumar ,&nbsp;Honglin Pan","doi":"10.1016/j.jastp.2025.106453","DOIUrl":"10.1016/j.jastp.2025.106453","url":null,"abstract":"<div><div>The aerosol-cloud interactions importantly influence the energy and water cycle of Earth-atmosphere system. The uncertainty of climate models is partly due to the lack of large-scale observational constraints of interaction between aerosol and water cloud. Based on CATS lidar time-resolved observations over the global marine region during 2015–2017, this study investigates the vertical effect of aerosol on marine water clouds, and evaluates the covariate influence of meteorological factors combined with European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis meteorological data. The mutual roles between aerosols as cloud condensation nucleation (CCN) and meteorological variables (temperature and relative humidity) contribute to the non-linear relationship of interactions between aerosol and water clouds. The results provide effective constraints for the parameterizations of aerosol-cloud interactions in current climate models.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106453"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143418888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Total electron content at an equatorial station during low solar activity: Geomagnetic activity effects emphasis","authors":"Sarvesh Kumar ,&nbsp;Sushil Kumar","doi":"10.1016/j.jastp.2024.106415","DOIUrl":"10.1016/j.jastp.2024.106415","url":null,"abstract":"<div><div>The initial results of Total Electron Content (TEC) data from September 2017 to November 2018 recorded over an equatorial station, Tarawa (geographic: 1.33°N, 173.01°E, geomagnetic: 2.68°S, 114.26°W) are presented which showed diurnal TEC maxima between 15:00–14:00 LT. The seasonal and semi-annual variations in the VTEC are clear, along with the less occurring winter anomalies and TEC bite-outs. The VTEC on magnetically disturbed days was higher than on quiet days. VTEC response to seven geomagnetic storms (5 moderate and 2 intense) showed positive ionospheric effect by all storms during their main phase. The VTEC response to two selected geomagnetic storms of 7–8 November 2017 (moderate strength, <em>Dst</em> = −72 nT) and 25–26 August 2018 (intense strength, <em>Dst</em> index = −174 nT) has been presented. During the November storm, TEC decreased by about 25.6% during the first step development of the main phase and increased by approximately 26.2% during the second step of main phase development. A long duration (&gt;24 h) increase in VTEC of about 47.3% was found during the main phase of the August storm. VTEC changes during the main phase of both storms are due to the storm-time auroral prompt penetrating electric field, while the disturbance dynamo electric field produced negative ionospheric effects during their recovery phases as indicated by changes in equatorial electrojet values obtained from SWARM A, B, and C satellites and <em>AE</em> index, respectively. The global O/N₂ gas data from the Global Ultraviolet Imager (GUVI) onboard TIMED spacecraft show that O/N₂ changes, to a lesser extent, were also responsible for the geomagnetic storm effects observed at our station.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106415"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}