Pub Date : 2025-03-18DOI: 10.1016/j.jastp.2025.106493
Andreas Keiling
In this study, we investigated the dynamics of Alfvén waves as a global phenomenon in the solar wind-magnetosphere coupling as it occurs at the entry point to the dayside auroral acceleration region. It was found that total Alfvén wave power over the dayside auroral zone increases from 1.3 to 5.5 GW with increasing -Dst value, or alternatively, from minor, to moderate, and to major storm. As the storm intensity increases, the Alfvénic “band” (Alfvénic oval) expands to lower latitude with a peak at 76° invariant latitude (ILT) during the initial phase and a peak at 72° ILT during the storm phase of moderate to strong storms. In comparison with the nightside Alfvénic activity, the most striking result was that during the initial phase, enhanced Alfvén wave power mostly occurred on the dayside, which is in contrast to the storm phase which shows strong enhancement on both dayside and nightside. The different sources of initial phase and storm phase suggest different underlying Alfvén wave generation mechanisms in the dayside. Furthermore, similarity in distribution to the dayside storm aurora during the initial phase suggests contributions of Alfvénic auroral acceleration.
{"title":"Dayside dynamics of Alfvén waves during geomagnetic storms, including the initial phase","authors":"Andreas Keiling","doi":"10.1016/j.jastp.2025.106493","DOIUrl":"10.1016/j.jastp.2025.106493","url":null,"abstract":"<div><div>In this study, we investigated the dynamics of Alfvén waves as a global phenomenon in the solar wind-magnetosphere coupling as it occurs at the entry point to the dayside auroral acceleration region. It was found that total Alfvén wave power over the dayside auroral zone increases from 1.3 to 5.5 GW with increasing -<em>Dst</em> value, or alternatively, from minor, to moderate, and to major storm. As the storm intensity increases, the Alfvénic “band” (Alfvénic oval) expands to lower latitude with a peak at 76° invariant latitude (ILT) during the initial phase and a peak at 72° ILT during the storm phase of moderate to strong storms. In comparison with the nightside Alfvénic activity, the most striking result was that during the initial phase, enhanced Alfvén wave power mostly occurred on the dayside, which is in contrast to the storm phase which shows strong enhancement on both dayside and nightside. The different sources of initial phase and storm phase suggest different underlying Alfvén wave generation mechanisms in the dayside. Furthermore, similarity in distribution to the dayside storm aurora during the initial phase suggests contributions of Alfvénic auroral acceleration.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106493"},"PeriodicalIF":1.8,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686432","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}
Pub Date : 2025-03-16DOI: 10.1016/j.jastp.2025.106489
Samuel T. Ogunjo , Bolarinwa J. Adekoya , Ayomide O. Olabode
Statistical analysis of inter-event times has been employed to gain information about drivers and classification of events such as neuron spikes and earthquake events. This study extends the concept of inter-event statistics to the space time analysis of lightning events across three global hotspot. Using WWLLN Global Lightning Climatology data spanning 11 years (2010 - 2021), lightning waiting time was evaluated using burstiness, probability distribution, and fractal analysis. Results obtained in this study showed that lightning events at hot spot regions are driven by Poisson processes while the surrounding regions with low lightning activities are bursty in nature. Attempts were made to fit lightning event times to three probability distribution functions - Lognormal, Gamma, and Normal distribution. Both Lognormal and Gamma distributions were found to be good fit for lightning waiting times, while the Normal distribution showed poor performance. Complex analysis of lightning waiting times were also considered using entropy and fractal analysis. Persistence was observed in lightning waiting times across the three hotspot regions considered.
{"title":"Spatial structure, distribution, and fractal analysis of lightning waiting times in three global hotspots","authors":"Samuel T. Ogunjo , Bolarinwa J. Adekoya , Ayomide O. Olabode","doi":"10.1016/j.jastp.2025.106489","DOIUrl":"10.1016/j.jastp.2025.106489","url":null,"abstract":"<div><div>Statistical analysis of inter-event times has been employed to gain information about drivers and classification of events such as neuron spikes and earthquake events. This study extends the concept of inter-event statistics to the space time analysis of lightning events across three global hotspot. Using WWLLN Global Lightning Climatology data spanning 11 years (2010 - 2021), lightning waiting time was evaluated using burstiness, probability distribution, and fractal analysis. Results obtained in this study showed that lightning events at hot spot regions are driven by Poisson processes while the surrounding regions with low lightning activities are bursty in nature. Attempts were made to fit lightning event times to three probability distribution functions - Lognormal, Gamma, and Normal distribution. Both Lognormal and Gamma distributions were found to be good fit for lightning waiting times, while the Normal distribution showed poor performance. Complex analysis of lightning waiting times were also considered using entropy and fractal analysis. Persistence was observed in lightning waiting times across the three hotspot regions considered.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106489"},"PeriodicalIF":1.8,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637774","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}
Pub Date : 2025-03-15DOI: 10.1016/j.jastp.2025.106488
V. Pitsis , D. Vassiliadis , A.Z. Boutsi , G. Balasis , I.A. Daglis
In recent years, remote sensing of magnetospheric and ionospheric currents using magnetometer arrays has improved considerably in geographic coverage, precision, and time resolution. Magnetic measurements have been used to detect and interpret a wide range of processes such as convection, solar wind (SW) compressions, substorms, magnetic storms (MSs), and more localized effects such as traveling ionospheric vortices, waves, etc. It is important to develop time- and frequency-domain methods that take advantage of these new observational capabilities. Here we apply a basic, but powerful correlation-based method for measuring the location and width of geospace current over a wide geomagnetic-latitude range. We compute the correlation matrix of the horizontal component of the magnetic field and use the structure of the matrix to measure the spatial extent of three current types. The method is applied to two recent, well-known magnetic-storm intervals (March 2015 and August 2018; 27 days each) as well as pre-storm activity intervals; but can be adapted to shorter time intervals by using higher time-resolution field data. We find that the correlation matrix is divided into three blocks, or geomagnetic latitudinal ranges, which are readily understood in terms of the footprint of the ring current, auroral electrojets, and polar convection intensifications. The matrix structure changes depending on intensity and pattern of geomagnetic activity (before, during and after the storm), and magnetic local time (MLT) range, with direct physical interpretation. The high correlations in each region are a quantitative measure of magnetospheric coherence. The results show how the correlation-matrix analysis can be used in quantitative remote sensing of spatial and temporal features of geospace activity.
{"title":"Latitudinal range of geospace currents inferred from correlation matrix analysis of ground magnetic variations during magnetic storms","authors":"V. Pitsis , D. Vassiliadis , A.Z. Boutsi , G. Balasis , I.A. Daglis","doi":"10.1016/j.jastp.2025.106488","DOIUrl":"10.1016/j.jastp.2025.106488","url":null,"abstract":"<div><div>In recent years, remote sensing of magnetospheric and ionospheric currents using magnetometer arrays has improved considerably in geographic coverage, precision, and time resolution. Magnetic measurements have been used to detect and interpret a wide range of processes such as convection, solar wind (SW) compressions, substorms, magnetic storms (MSs), and more localized effects such as traveling ionospheric vortices, waves, etc. It is important to develop time- and frequency-domain methods that take advantage of these new observational capabilities. Here we apply a basic, but powerful correlation-based method for measuring the location and width of geospace current over a wide geomagnetic-latitude range. We compute the correlation matrix of the horizontal component of the magnetic field and use the structure of the matrix to measure the spatial extent of three current types. The method is applied to two recent, well-known magnetic-storm intervals (March 2015 and August 2018; 27 days each) as well as pre-storm activity intervals; but can be adapted to shorter time intervals by using higher time-resolution field data. We find that the correlation matrix is divided into three blocks, or geomagnetic latitudinal ranges, which are readily understood in terms of the footprint of the ring current, auroral electrojets, and polar convection intensifications. The matrix structure changes depending on intensity and pattern of geomagnetic activity (before, during and after the storm), and magnetic local time (MLT) range, with direct physical interpretation. The high correlations in each region are a quantitative measure of magnetospheric coherence. The results show how the correlation-matrix analysis can be used in quantitative remote sensing of spatial and temporal features of geospace activity.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106488"},"PeriodicalIF":1.8,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686431","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}
Pub Date : 2025-03-12DOI: 10.1016/j.jastp.2025.106486
Ahmad E. Samman , Mostafa Morsy , Abdallah Abdaldym , Heshmat Abdel Basset
The spatio-temporal distribution of global solar radiation (GSR) is essential for the effective integration of photovoltaic (PV) energy systems. Therefore, this study aims to investigate the long-term trend, variation, fluctuation, and abrupt changes of the GSR over Kingdom of Saudi Arabia (KSA). The observed GSR data from World Radiation Data Center (WRDC) were used to evaluate the gridded 0.25° × 0.25° CLARA-A3 dataset at the available five stations. The GSR data at another 10 stations from the CLARA-A3 dataset covering the different climatic regions in KSA during the period from 1979 to 2023 were extracted to facilitate the analysis and interpretation of GSR. The results showed that, CLARA-A3 produced high accuracy and reliability GSR data over KSA. Also, the monthly GSR ranges from 140 to 240 W/m2 as minimum during winter and from 280 to 340 W/m2 as maximum during summer. The coefficient of variation (CV) gradient, both annual and seasonal, varies from around 0.5 %–6 %, with the highest gradient occurring in the mountainous regions in southwestern KSA. Furthermore, the GSR has a positive Mann-Kendall (MK) trend during spring, followed by winter and annual trends, whereas a negative MK trend is detected during summer. The climatological variability of annual GSR behavior, analyzed using Gaussian and binomial low-pass filters, indicates a positive trend at the majority of stations. Finally, the first positive abrupt change in GSR values at all stations is found in 1999 and 2001, while the negative abrupt change was detected in 1992 at only three stations.
{"title":"Assessing climate variability and trends in global solar radiation over Saudi Arabia using the CLARA-A3 dataset","authors":"Ahmad E. Samman , Mostafa Morsy , Abdallah Abdaldym , Heshmat Abdel Basset","doi":"10.1016/j.jastp.2025.106486","DOIUrl":"10.1016/j.jastp.2025.106486","url":null,"abstract":"<div><div>The spatio-temporal distribution of global solar radiation (GSR) is essential for the effective integration of photovoltaic (PV) energy systems. Therefore, this study aims to investigate the long-term trend, variation, fluctuation, and abrupt changes of the GSR over Kingdom of Saudi Arabia (KSA). The observed GSR data from World Radiation Data Center (WRDC) were used to evaluate the gridded 0.25° × 0.25° CLARA-A3 dataset at the available five stations. The GSR data at another 10 stations from the CLARA-A3 dataset covering the different climatic regions in KSA during the period from 1979 to 2023 were extracted to facilitate the analysis and interpretation of GSR. The results showed that, CLARA-A3 produced high accuracy and reliability GSR data over KSA. Also, the monthly GSR ranges from 140 to 240 W/m<sup>2</sup> as minimum during winter and from 280 to 340 W/m<sup>2</sup> as maximum during summer. The coefficient of variation (CV) gradient, both annual and seasonal, varies from around 0.5 %–6 %, with the highest gradient occurring in the mountainous regions in southwestern KSA. Furthermore, the GSR has a positive Mann-Kendall (MK) trend during spring, followed by winter and annual trends, whereas a negative MK trend is detected during summer. The climatological variability of annual GSR behavior, analyzed using Gaussian and binomial low-pass filters, indicates a positive trend at the majority of stations. Finally, the first positive abrupt change in GSR values at all stations is found in 1999 and 2001, while the negative abrupt change was detected in 1992 at only three stations.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106486"},"PeriodicalIF":1.8,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620153","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}
Pub Date : 2025-03-12DOI: 10.1016/j.jastp.2025.106494
Yu Zhao
Understanding the spatiotemporal patterns and factors influencing PM2.5 concentrations is crucial for implementing effective pollution control measures. In this study, we used a gridded dataset of annal PM2.5 concentrations, together with meteorological and land cover data from 2000 to 2020, to analyze the spatial‒temporal patterns of PM2.5 concentrations and their responses to land use changes and meteorological factors in Shaanxi Province, China. Trend analysis was employed to identify overall temporal patterns, a random forest (RF) was used to evaluate the importance of influencing factors, and the geographically weighted regression (GWR) method was applied to assess spatial heterogeneity and local effects. The annual PM2.5 concentration decreased by 43.52 % from 2000 to 2020, with higher concentrations in the central region and lower concentrations in the southern and northern areas. The PM2.5 concentration was negatively correlated with the interconversion of forests and grasslands and positively correlated with conversions among croplands, impervious surfaces, and water bodies. The RF regression results indicated that croplands, impervious surfaces, and their mutual interconversions exerted a greater impact on PM2.5 concentrations than did the other land use types. The GWR analysis results revealed that the factors influencing PM2.5 concentration, in descending order of importance, were as follows: wind speed, precipitation, relative humidity, temperature, sunshine duration, atmospheric pressure, conversion of impervious surfaces to cropland, conversion of cropland to impervious surfaces, unconverted cropland, and unconverted impervious surfaces.
{"title":"Spatiotemporal distribution of PM2.5 concentrations in Shaanxi Province, China, and its responses to land use changes and meteorological factors","authors":"Yu Zhao","doi":"10.1016/j.jastp.2025.106494","DOIUrl":"10.1016/j.jastp.2025.106494","url":null,"abstract":"<div><div>Understanding the spatiotemporal patterns and factors influencing PM<sub>2.5</sub> concentrations is crucial for implementing effective pollution control measures. In this study, we used a gridded dataset of annal PM<sub>2.5</sub> concentrations, together with meteorological and land cover data from 2000 to 2020, to analyze the spatial‒temporal patterns of PM<sub>2.5</sub> concentrations and their responses to land use changes and meteorological factors in Shaanxi Province, China. Trend analysis was employed to identify overall temporal patterns, a random forest (RF) was used to evaluate the importance of influencing factors, and the geographically weighted regression (GWR) method was applied to assess spatial heterogeneity and local effects. The annual PM<sub>2.5</sub> concentration decreased by 43.52 % from 2000 to 2020, with higher concentrations in the central region and lower concentrations in the southern and northern areas. The PM<sub>2.5</sub> concentration was negatively correlated with the interconversion of forests and grasslands and positively correlated with conversions among croplands, impervious surfaces, and water bodies. The RF regression results indicated that croplands, impervious surfaces, and their mutual interconversions exerted a greater impact on PM<sub>2.5</sub> concentrations than did the other land use types. The GWR analysis results revealed that the factors influencing PM<sub>2.5</sub> concentration, in descending order of importance, were as follows: wind speed, precipitation, relative humidity, temperature, sunshine duration, atmospheric pressure, conversion of impervious surfaces to cropland, conversion of cropland to impervious surfaces, unconverted cropland, and unconverted impervious surfaces.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106494"},"PeriodicalIF":1.8,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636740","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}
Pub Date : 2025-03-07DOI: 10.1016/j.jastp.2025.106492
Jia Yue , Ningchao Wang
The adiabatic cooling and warming in the mesosphere and lower thermosphere (MLT) are estimated utilizing the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) measured CO2 volume mixing ratio (VMR) vertical displacement from the global mean CO2 VMR. This work confirms that the summer mesopause temperature is largely controlled by adiabatic cooling instead of any absorptive heating or chemical heating. The paper also reveals a previously overlooked layer of adiabatic warming in summer and adiabatic cooling in winter in the lower thermosphere, being driven by downwelling and upwelling associated with the winter-to-summer circulation. Since this adiabatic warming/cooling process is embedded in the thermosphere where the mean temperature rises sharply, it is not as distinct without removing the global mean temperature. The mesospheric temperature is the opposite, being lacking of strong heating sources. The heating anomaly (∼100 K) in the summer lower thermosphere is substantial. Because auroral heating also occurs in the geomagnetic polar lower thermosphere, the interaction between the adiabatic warming/cooling in the lower thermosphere and auroral heating should be considered in future studies.
{"title":"Estimation of adiabatic cooling and warming in the mesosphere and lower thermosphere","authors":"Jia Yue , Ningchao Wang","doi":"10.1016/j.jastp.2025.106492","DOIUrl":"10.1016/j.jastp.2025.106492","url":null,"abstract":"<div><div>The adiabatic cooling and warming in the mesosphere and lower thermosphere (MLT) are estimated utilizing the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) measured CO<sub>2</sub> volume mixing ratio (VMR) vertical displacement from the global mean CO<sub>2</sub> VMR. This work confirms that the summer mesopause temperature is largely controlled by adiabatic cooling instead of any absorptive heating or chemical heating. The paper also reveals a previously overlooked layer of adiabatic warming in summer and adiabatic cooling in winter in the lower thermosphere, being driven by downwelling and upwelling associated with the winter-to-summer circulation. Since this adiabatic warming/cooling process is embedded in the thermosphere where the mean temperature rises sharply, it is not as distinct without removing the global mean temperature. The mesospheric temperature is the opposite, being lacking of strong heating sources. The heating anomaly (∼100 K) in the summer lower thermosphere is substantial. Because auroral heating also occurs in the geomagnetic polar lower thermosphere, the interaction between the adiabatic warming/cooling in the lower thermosphere and auroral heating should be considered in future studies.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106492"},"PeriodicalIF":1.8,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578208","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}
Pub Date : 2025-03-05DOI: 10.1016/j.jastp.2025.106491
Oleg S. Ugolnikov , Nikolay N. Pertsev , Vladimir I. Perminov , Ilya S. Yankovsky , Dmitry N. Aleshin , Ekaterina N. Tipikina , Alexander A. Ilyukhin , Egor O. Ugolnikov , Stanislav A. Korotkiy , Olga Yu. Golubeva , Andrey M. Tatarnikov , Sergey G. Zheltoukhov , Alexey V. Popov , Alexey S. Sushkov , Egor A. Volkov , Natalya S. Krapkina , Damir I. Yalyshev
The results of simultaneous measurements of noctilucent clouds (NLC) position in a number of ground-based locations are presented. Observational data of 14 bright NLC events over 5 years is used for building the altitude maps of the cloud fields using the triangulation technique updated for multi-location case. The statistical distribution of NLC altitude and its change during the summer season is considered. Mean NLC altitudes are compared with estimations by colorimetric technique based on the same data and simple radiation transfer model. This can be used to check the model and estimate the accuracy of single-camera technique of NLC altitude measurements. Clouds appear in the altitude range from 79 to 84 km, the average height of NLC is found to be 81.4 km, while the mean brightness-weighted altitude is 0.5 km below this. The brightest clouds are observed near 80 km, where the ice particles can reach the maximal size. Possible effects of the increased height of NLC during the beginning of summer (June) and maximal solar activity (2024) are noted. Results and methods are suggested for the net ground-based survey of noctilucent clouds.
{"title":"Five-years altitude statistics of noctilucent clouds based on multi-site wide-field camera survey","authors":"Oleg S. Ugolnikov , Nikolay N. Pertsev , Vladimir I. Perminov , Ilya S. Yankovsky , Dmitry N. Aleshin , Ekaterina N. Tipikina , Alexander A. Ilyukhin , Egor O. Ugolnikov , Stanislav A. Korotkiy , Olga Yu. Golubeva , Andrey M. Tatarnikov , Sergey G. Zheltoukhov , Alexey V. Popov , Alexey S. Sushkov , Egor A. Volkov , Natalya S. Krapkina , Damir I. Yalyshev","doi":"10.1016/j.jastp.2025.106491","DOIUrl":"10.1016/j.jastp.2025.106491","url":null,"abstract":"<div><div>The results of simultaneous measurements of noctilucent clouds (NLC) position in a number of ground-based locations are presented. Observational data of 14 bright NLC events over 5 years is used for building the altitude maps of the cloud fields using the triangulation technique updated for multi-location case. The statistical distribution of NLC altitude and its change during the summer season is considered. Mean NLC altitudes are compared with estimations by colorimetric technique based on the same data and simple radiation transfer model. This can be used to check the model and estimate the accuracy of single-camera technique of NLC altitude measurements. Clouds appear in the altitude range from 79 to 84 km, the average height of NLC is found to be 81.4 km, while the mean brightness-weighted altitude is 0.5 km below this. The brightest clouds are observed near 80 km, where the ice particles can reach the maximal size. Possible effects of the increased height of NLC during the beginning of summer (June) and maximal solar activity (2024) are noted. Results and methods are suggested for the net ground-based survey of noctilucent clouds.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106491"},"PeriodicalIF":1.8,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578207","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}
Pub Date : 2025-03-04DOI: 10.1016/j.jastp.2025.106490
Ian Edmonds , Peter Killen
The spectral content of the El Nino Southern Oscillation (ENSO) is broad and complex, a characteristic shared by other climate variables. Spectral analysis of ENSO in different time intervals demonstrated that ENSO is frequency modulated. An analytical model in which the natural period of ENSO is frequency modulated by long term centennial range variation in solar activity was developed and shown to correlate well with the observed ENSO and reconstructed ENSO variation in the decadal periodicity range. A method for identifying the occurrence and the period of frequency modulation in climate variables was developed and tested.
{"title":"Is the variability of ENSO due to frequency modulation by the long term variation in solar activity?","authors":"Ian Edmonds , Peter Killen","doi":"10.1016/j.jastp.2025.106490","DOIUrl":"10.1016/j.jastp.2025.106490","url":null,"abstract":"<div><div>The spectral content of the El Nino Southern Oscillation (ENSO) is broad and complex, a characteristic shared by other climate variables. Spectral analysis of ENSO in different time intervals demonstrated that ENSO is frequency modulated. An analytical model in which the natural period of ENSO is frequency modulated by long term centennial range variation in solar activity was developed and shown to correlate well with the observed ENSO and reconstructed ENSO variation in the decadal periodicity range. A method for identifying the occurrence and the period of frequency modulation in climate variables was developed and tested.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106490"},"PeriodicalIF":1.8,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143577577","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}
Pub Date : 2025-03-03DOI: 10.1016/j.jastp.2025.106452
Agegnehu Sisay , Tsegaye Kassa
This study analyzed the longitudinal variations of phase scintillation over United States (AB21 and AC66), Canada (UCLU, CAGS, ESCU, and STJO), Germany (HUEG and WTZZ), Ukraine (UZHL), Kazakhstan (KRTU), and Russia (BADG) sectors as the result of the intense geomagnetic storms of March 2015, June 2015, and December 2015 during solar cycle 24. Ground-based Global Positioning System (GPS) receivers, solar wind speed and magnetic (IMF Bz and Dst) data are used for this study. Total Electron Content (TEC) was used to derive the ionospheric phase scintillation/irregularities proxy indices, e.g., rate of change of TEC (ROT) and ROT index (ROTI).These indices were characterized alongside with the Disturbance Storm Time (Dst), Solar Wind Speed (Vsw), and Z component of Interplanetary Magnetic Field (IMF Bz) to see the effect of geomagnetic storm on horizontal component of geomagnetic field. Prompt Penetration of Electric Field (PPEF) modulated the behavior of irregularities during the initial and recovery phases of the geomagnetic storms (Demelash and Kassa, 2023). As a result, irregularities in the ionosphere over Canada, Germany, Ukraine, Kazakhstan, and Russia were found to range from weak to moderate in intensity. Regions in the United States, however, ranged between weak and strong. These phase scintillation generally occurred during the initial, main, and recovery phases of the storms at all selected stations. The effect of electric field was found to depend on the local time at which the IMF Bz turned into southward. The generation (inhibition) of phase scintillation is related to the effect of eastward (west-ward) storm time electric field disturbance dynamo electric fields and prompt penetration electric fields that created favorable (unfavorable) conditions for the generation of irregularities by uplifting (lowering) the F region. These findings highlight the presence of phase scintillation and fluctuations during different phases of geomagnetic storms, with varying intensities and durations across multiple locations.
{"title":"Longitudinal responses of phase scintillation from ground stations during geomagnetic storms","authors":"Agegnehu Sisay , Tsegaye Kassa","doi":"10.1016/j.jastp.2025.106452","DOIUrl":"10.1016/j.jastp.2025.106452","url":null,"abstract":"<div><div>This study analyzed the longitudinal variations of phase scintillation over United States (AB21 and AC66), Canada (UCLU, CAGS, ESCU, and STJO), Germany (HUEG and WTZZ), Ukraine (UZHL), Kazakhstan (KRTU), and Russia (BADG) sectors as the result of the intense geomagnetic storms of March 2015, June 2015, and December 2015 during solar cycle 24. Ground-based Global Positioning System (GPS) receivers, solar wind speed and magnetic (IMF Bz and Dst) data are used for this study. Total Electron Content (TEC) was used to derive the ionospheric phase scintillation/irregularities proxy indices, e.g., rate of change of TEC (ROT) and ROT index (ROTI).These indices were characterized alongside with the Disturbance Storm Time (Dst), Solar Wind Speed (Vsw), and Z component of Interplanetary Magnetic Field (IMF Bz) to see the effect of geomagnetic storm on horizontal component of geomagnetic field. Prompt Penetration of Electric Field (PPEF) modulated the behavior of irregularities during the initial and recovery phases of the geomagnetic storms (Demelash and Kassa, 2023). As a result, irregularities in the ionosphere over Canada, Germany, Ukraine, Kazakhstan, and Russia were found to range from weak to moderate in intensity. Regions in the United States, however, ranged between weak and strong. These phase scintillation generally occurred during the initial, main, and recovery phases of the storms at all selected stations. The effect of electric field was found to depend on the local time at which the IMF Bz turned into southward. The generation (inhibition) of phase scintillation is related to the effect of eastward (west-ward) storm time electric field disturbance dynamo electric fields and prompt penetration electric fields that created favorable (unfavorable) conditions for the generation of irregularities by uplifting (lowering) the F region. These findings highlight the presence of phase scintillation and fluctuations during different phases of geomagnetic storms, with varying intensities and durations across multiple locations.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106452"},"PeriodicalIF":1.8,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562554","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}
This study investigates aerosol characteristics using ground-based measurements at two distinct regions, Mohal-Kullu (31.9°N, 77.12°E; 1154 m amsl) and Kosi-Katarmal (29.64°N, 79.62°E; 1225 m amsl), from July 2019 to June 2022. The average Black Carbon (BC) concentrations were 1.5 ± 1.0 μg m−3 at Mohal and 1.1 ± 1.4 μg m−3 at Katarmal. BC showed strong seasonal variability, with maxima during post-monsoon (2.6 ± 1.0 μg m−3) and pre-monsoon (1.8 ± 0.5 μg m−3) seasons. The diurnal variation displayed distinct morning and evening peaks in all the seasons. High pre-monsoon AOD500 (0.30 ± 0.06 to 0.54 ± 0.08) and low values of Ångström exponent (0.67 ± 0.10 to 0.95 ± 0.30) indicated dominance of large particles, whereas lower AOD500 (0.21 ± 0.07 to 0.25 ± 0.03) in post-monsoon and winter, along with larger Ångström exponent (1.05 ± 0.74 to 1.13 ± 0.11), indicated smaller particles. Satellite-derived (OMI and MAIAC) AOD500 showed weak to moderate correlation with ground-based measurements at Mohal (R = 0.4639 for MAIAC, R = 0.1402 for OMI) and Katarmal (R = 0.3976 for MAIAC, R = 0.2980 for OMI). Using optical properties of aerosols and clouds (OPAC) and Santa Barbara discrete ordinate radiative transfer (SBDART) models, the short-wave aerosol radiative forcing (SWARF) was found negative at the surface and top of the atmosphere but positive in the atmosphere, suggesting significant surface cooling and atmospheric warming leading to high heating rates, respectively. Annual mean atmospheric radiative forcing was 27.36 ± 6.00 Wm−2 at Mohal and 21.87 ± 7.26 Wm−2 at Katarmal. These findings may have consequences for planning air pollution strategies and understanding the effects of regional climate change.
{"title":"Aerosol Optical Properties and its radiative effects over two topographically different locations of the Indian Himalayan Region","authors":"Archana Bawari , Jagdish Chandra Kuniyal , Sheetal Chaudhary , Renu Lata , Bimal Pande","doi":"10.1016/j.jastp.2025.106487","DOIUrl":"10.1016/j.jastp.2025.106487","url":null,"abstract":"<div><div>This study investigates aerosol characteristics using ground-based measurements at two distinct regions, Mohal-Kullu (31.9°N, 77.12°E; 1154 m amsl) and Kosi-Katarmal (29.64°N, 79.62°E; 1225 m amsl), from July 2019 to June 2022. The average Black Carbon (BC) concentrations were 1.5 ± 1.0 μg m<sup>−3</sup> at Mohal and 1.1 ± 1.4 μg m<sup>−3</sup> at Katarmal. BC showed strong seasonal variability, with maxima during post-monsoon (2.6 ± 1.0 μg m<sup>−3</sup>) and pre-monsoon (1.8 ± 0.5 μg m<sup>−3</sup>) seasons. The diurnal variation displayed distinct morning and evening peaks in all the seasons. High pre-monsoon AOD<sub>500</sub> (0.30 ± 0.06 to 0.54 ± 0.08) and low values of Ångström exponent (0.67 ± 0.10 to 0.95 ± 0.30) indicated dominance of large particles, whereas lower AOD<sub>500</sub> (0.21 ± 0.07 to 0.25 ± 0.03) in post-monsoon and winter, along with larger Ångström exponent (1.05 ± 0.74 to 1.13 ± 0.11), indicated smaller particles. Satellite-derived (OMI and MAIAC) AOD<sub>500</sub> showed weak to moderate correlation with ground-based measurements at Mohal (R = 0.4639 for MAIAC, R = 0.1402 for OMI) and Katarmal (R = 0.3976 for MAIAC, R = 0.2980 for OMI). Using optical properties of aerosols and clouds (OPAC) and Santa Barbara discrete ordinate radiative transfer (SBDART) models, the short-wave aerosol radiative forcing (SWARF) was found negative at the surface and top of the atmosphere but positive in the atmosphere, suggesting significant surface cooling and atmospheric warming leading to high heating rates, respectively. Annual mean atmospheric radiative forcing was 27.36 ± 6.00 Wm<sup>−2</sup> at Mohal and 21.87 ± 7.26 Wm<sup>−2</sup> at Katarmal. These findings may have consequences for planning air pollution strategies and understanding the effects of regional climate change.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106487"},"PeriodicalIF":1.8,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143550776","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}
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