Journal of Atmospheric and Solar-Terrestrial Physics最新文献

{"title":"Understanding the performance of global precipitation products for hydrological modeling in the data-scarce morphologically complex central Himalayan region","authors":"Sneha Sandilya ,&nbsp;Sunayana Singh ,&nbsp;Sonu Kumar ,&nbsp;Jitendra Rajput","doi":"10.1016/j.jastp.2025.106513","DOIUrl":"10.1016/j.jastp.2025.106513","url":null,"abstract":"<div><div>Developing a hydrological model is challenging in ungauged river basins. Hydrological modeling requires historical precipitation estimates. Global precipitation products (GPPs) have equipped hydrologists with a significant resource for hydrological applications such as flood modeling and forecasting. This study compares the quality and hydrological utility of different GPPs, TRMM 3B42, TRMM 3B42RT, APHRODITE, and SM2RAIN in the Gandak river basin (Nepal and India). The study reveals that among the four GPPs, the SM2RAIN had the least average Root Mean Squared Error (RMSE) of 5.83 mm/day, and TRMM 3B42RT had the highest RMSE of 11 mm/day. When it comes to R-squared, SM2RAIN had the highest value (0.37), and TRMM 3B42 showed the lowest at 0.07. Similarly, Bias for SM2RAIN showed the most negligible average bias, which was −5.34 %, and TRMM 3B42 indicated the highest bias of 28.71 %. POD for SM2RAIN was the highest at 0.83 and the lowest for TRMM RT (0.67). Similarly, when a hydrological model using MIKE 11 NAM model was developed and calibrated with gauge data, TRMM 3B42 (daily), TRMM 3B42RT, and SM2RAIN, the NSE were calculated to be 0.74, 0.62, −0.25 and 0.74 respectively for the calibration period and 0.67, 0.51, 0.42 and 0.5, respectively for the validation period. The TRMM 3B42 RT data sets were not found to be suitable for hydrological modeling in the Gandak river basin as mostly the NSE value was found to be negative. The study reveals that the best-suited product among the four GPPs for hydrological simulations in the central Himalayan region is SM2RAIN, followed by the TRMM 3B42.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"271 ","pages":"Article 106513"},"PeriodicalIF":1.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851934","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":"Solar terminator related variations in geomagnetic field","authors":"Alexey Andreyev ,&nbsp;Vyacheslav Somsikov ,&nbsp;Vitaliy Kapytin ,&nbsp;Yekaterina Chsherbulova","doi":"10.1016/j.jastp.2025.106517","DOIUrl":"10.1016/j.jastp.2025.106517","url":null,"abstract":"<div><div>The solar terminator is a global, regular source of disturbances in various parameters of the Earth's atmosphere. The main feature of the solar terminator is its stability and precise regularity. To estimate the regular effects from the solar terminator in geomagnetic data, an analysis of averaged variations in the geomagnetic field components was performed based on long magnetic field time-series over the past 24 years from a large number of geomagnetic observatories. It was demonstrated that in addition to quasi-semidiurnal oscillations, Sq variations of the geomagnetic field contain relatively weak regular oscillations with periods of less than an hour, precisely tied to the moment of sunrise and sunset (passage of the solar terminator), as well as the passage of the terminator through the magnetically conjugate point.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"271 ","pages":"Article 106517"},"PeriodicalIF":1.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848709","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":"A novel approach to estimate surface refractivity with simple meteorological data","authors":"Olanrewaju Olukemi Soneye-Arogundade ,&nbsp;Bernhard Rappenglück","doi":"10.1016/j.jastp.2025.106510","DOIUrl":"10.1016/j.jastp.2025.106510","url":null,"abstract":"<div><div>This study analyzes surface refractivity pattern<strong>s</strong> and proposes six empirical models for its estimation in Houston, Texas, a subtropical climate region of the United States, using 18 years (2006–2023) of meteorological data. Monthly and yearly variations revealed a seasonal pattern peaking in summer (372.4 N units in July) and reaching its lowest in winter (327.8 N units in December). An analysis of the contributions of the dry and wet components shows the dry component dominating in the winter (61–63 %) and the wet component prevailing in the summer (56–60 %). The proposed models were developed using air temperature, atmospheric pressure, and relative humidity as input variables. Models’ performances were evaluated using statistical metrics and the Akaike Information Criterion (AIC). The models' residuals closely followed a normal distribution, indicating robust and reliable predictive capabilities that enhance understanding of surface refractivity. Model 3, a two-variable linear model incorporating air temperature and atmospheric pressure (<span><math><mrow><msub><mi>N</mi><mi>i</mi></msub><mo>=</mo><mo>−</mo><mn>33.7689</mn><mo>+</mo><mn>1.3234</mn><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow><mo>−</mo><mn>0.0069</mn><mrow><mo>(</mo><mi>P</mi><mo>)</mo></mrow></mrow></math></span>, was identified as the best performing model with the lowest AIC (6.829), AIC_C (12.543), and ΔAIC_C (0.000) values and deviations between −1.80 % and 2.38 % from the measured values. Model 1, a simpler single-variable linear model using only air temperature (<span><math><mrow><msub><mi>N</mi><mi>i</mi></msub><mo>=</mo><mo>−</mo><mn>41.2088</mn><mo>+</mo><mn>1.3250</mn><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span>), also showed strong performance, with deviations ranging from 0.12 % to 6.36 %. Comparative analysis indicated that locally developed models significantly outperformed the standard refractivity equation, highlighting the importance of location-specific empirical models for accurate surface refractivity estimation. Importantly, these models rely solely on readily accessible air temperature and atmospheric pressure measurements, eliminating the need for solar radiation data and enabling their easier application across diverse regions. These findings have implications for modeling radio wave propagation, radar systems, telecommunications planning, and atmospheric studies in similar climate regions.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"271 ","pages":"Article 106510"},"PeriodicalIF":1.8,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143842624","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":"Vertical acoustic resonance in the atmosphere as a source of Pc5 geomagnetic pulsations","authors":"V.V. Surkov","doi":"10.1016/j.jastp.2025.106511","DOIUrl":"10.1016/j.jastp.2025.106511","url":null,"abstract":"<div><div>Some strong earthquakes and volcano eruptions are accompanied by atmospheric pressure variations and geomagnetic perturbations (GMPs), which contain spectral spikes in the Pc5 frequency range. GMPs are usually observed in epicentral areas of several hundred kilometers in size and in a geomagnetically conjugated region. This effect can be explained by the impact on the ionosphere of an atmospheric acoustic wave caused by seismic vibration of the earth's surface. A partial reflection of the acoustic wave from the region of a sharp change in atmospheric temperature near the bottom of the thermosphere can lead to a vertical acoustic resonance (VAR) in the area between the earth's surface and the thermosphere boundary. The acoustic wave partially penetrates into the ionosphere, thereby exciting ionospheric currents and GMPs in the Pc5 frequency range. In this study we develop a plane-stratified model of the atmosphere and ionosphere in order to examine spectrum of the first VAR harmonics. A set of 2D gas dynamics equations is treated to derive dispersion relations which determine the VAR resonant frequencies. Ionospheric currents and GMP are found in the approximation of a thin ionospheric <em>E</em>-layer with an inclined geomagnetic field. Analysis of the VAR dispersion relation shows that the resonant frequencies of the first three harmonics lies within 3.7<u>−</u>5.9 mHz, that is, in the Pc5 frequency range, while their logarithmic decrements range from zero to 0.6. The weak attenuation of VAR harmonics can explain the observed long duration of VAR and GMPs after a seismic event. Unlike previous studies, the effect of wind in the upper atmosphere is taken into account. It has been found that wind velocity weakly influences the resonant frequencies but it may greatly affect the attenuation coefficients of VAR harmonics. The model predicts a similar shape of GMPs detected near the epicenter of strong seismic events and in the magnetically conjugated arears, which is consistent with geomagnetic response to VAR detected by ground-based magnetometers.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"271 ","pages":"Article 106511"},"PeriodicalIF":1.8,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835317","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":"Atmospheric ozone modulation by cosmic ray Forbush decreases: Patterns and anomalies across multiple stations","authors":"Maghrabi A,&nbsp;Alghamdi Mayson,&nbsp;Abdulah Aldosari,&nbsp;Mohammed Al Mutairi,&nbsp;Mohammed Altlasi","doi":"10.1016/j.jastp.2025.106509","DOIUrl":"10.1016/j.jastp.2025.106509","url":null,"abstract":"<div><div>This investigation systematically examines the effects of 13 Forbush Decrease (FD) events on the total ozone column (TOC) and ozone concentrations within six stratospheric layers (L6–L11). The primary aim is to quantify the magnitude, temporal dynamics, and latitudinal variability of ozone responses to FD-driven CR perturbations. Using superposed epoch analysis, ozone data from 18 globally distributed stations (spanning 55.8°N to −6.2°N) were analyzed over a 21-day window centered on each FD event, with deviations calculated relative to a 4-day pre-FD baseline (days −4 to −1). Results reveal a distinct latitudinal gradient in ozone responses: high-latitude stations (e.g., Moscow, 55.8°N; Copenhagen, 55.7°N) exhibit rapid and substantial increases in TOC (5–15 %, peaking within 3–4 days) and layer-specific ozone concentrations (e.g., L6: 8–16 % by days 3–4; L11: 3–10 % by days 0–4), attributed to CR-induced ionization processes. Conversely, low-latitude stations (e.g., Jakarta, −6.2°N; Hanoi, 21.0°N) show subdued and delayed responses (TOC: 1–6 %; layers: 1–5 %, peaking by days 5–8), likely due to photochemical suppression and enhanced atmospheric mixing. Vertical analysis highlights more pronounced CR-driven effects in the lower stratosphere (e.g., L6), with greater variability in the upper layers (e.g., L11), indicating altitudinal differences in ozone sensitivity to CR flux variations. These findings emphasize the pivotal role of CR flux reductions in influencing stratospheric ozone dynamics, with broader implications for atmospheric chemistry, radiative forcing, and climate systems. The results underscore the necessity for further mechanistic investigations and advanced coupled chemistry-climate modeling to deepen our understanding of these intricate solar-terrestrial interactions.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106509"},"PeriodicalIF":1.8,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828521","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":"Winter noctilucent clouds following sudden stratospheric warming: First observations","authors":"Oleg S. Ugolnikov","doi":"10.1016/j.jastp.2025.106507","DOIUrl":"10.1016/j.jastp.2025.106507","url":null,"abstract":"<div><div>Mesospheric structures identical to summer noctilucent clouds were observed during the nights of December 17–19, 2024 in Siberian Russia. Based on the available photo data, the mean altitude of the clouds 70.1 ± 1.5 km was measured by umbral colorimetric method. This coincided spatially and temporary with a deep temperature minimum below 160K in mesosphere, following the polar vortex displacement and the warming of stratosphere below the clouds. The satellite data on temperature and water vapor is used to study the nature of this unexpected event.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106507"},"PeriodicalIF":1.8,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143817501","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":"Evaluating growth rates of sprite streamers","authors":"George V. Naidis","doi":"10.1016/j.jastp.2025.106506","DOIUrl":"10.1016/j.jastp.2025.106506","url":null,"abstract":"<div><div>Downward-propagating positive sprite streamers are modeled. It is shown that, in agreement with recent high-speed video observations, at the initial stage of streamer propagation the streamer velocity increases with time with a nearly constant growth rate, varying almost proportionally to the streamer length. An approximate expression for the growth rate is presented as a function of the altitude, the driving electric field at this altitude and the peak electric field in the streamer head.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106506"},"PeriodicalIF":1.8,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143817502","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":"Automatic detection and classification of Spread-F in ionograms using convolutional neural network","authors":"Moheb Yacoub ,&nbsp;Edgardo E. Pacheco ,&nbsp;Moataz Abdelwahab ,&nbsp;Cesar De La Jara ,&nbsp;Ayman Mahrous","doi":"10.1016/j.jastp.2025.106504","DOIUrl":"10.1016/j.jastp.2025.106504","url":null,"abstract":"<div><div>Equatorial spread-F (ESF) is an irregularity caused by plasma instabilities on the night side that causes signal degradation and disruptions to the GNSS signals. Ionosondes could detect ESF as it appears as a diffused echo in the ionogram images. This study proposes a Convolutional Neural Network (CNN) model that can automatically detect ESF within the ionogram images and classify its type. The model has been trained using 2646 manually labeled ionograms from the Low Latitude Ionospheric Sensor Network (LISN) VIPIR Ionosondes in South America. The data used to train the model was measured from 2019 to 2024. The model was able to classify the testing images into six categories: Clear class, frequency spread-F (FSF), range spread-F (RSF), mixed spread-F (MSF), strong spread-F (SSF), and Unidentified class. It demonstrated high classification accuracy within the extracted test subset and a further random test, showcasing robustness and consistency in detection accuracy across all classes. Furthermore, the model performance has been evaluated and compared with other baseline models: VGG16, VGG19, ResNet18, and Inception-V3 in the same environment. Additionally, a comparison with published models is provided. Our model showed a higher consistency in classification accuracy across all classes compared to the mentioned models.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106504"},"PeriodicalIF":1.8,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735046","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":"Simultaneous evaluation of solar activity proxies during geomagnetic storms using principal component analysis: Case study of the African low and mid-latitude regions","authors":"Jean Claude Uwamahoro ,&nbsp;John Bosco Habarulema ,&nbsp;Dalia Buresova ,&nbsp;Nigussie Mezgebe Giday ,&nbsp;Valence Habyarimana ,&nbsp;Kateryna Aksonova ,&nbsp;Joseph Ntahompagaze ,&nbsp;Theogene Ndacyayisenga ,&nbsp;Ange Cynthia Umuhire","doi":"10.1016/j.jastp.2025.106477","DOIUrl":"10.1016/j.jastp.2025.106477","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We simultaneously evaluate the contributions of the mostly used solar activity indices to the modelling of geomagnetic storms using principal component analysis (PCA). The selected indices are the sunspot number (SSN), solar radio flux at a wavelength of 10.7 cm (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), 12-month running average of SSN (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mn&gt;12&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), 81-day running average of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;81&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), and the modified &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; index herein referred to as &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. The assessment of these indices was accomplished by first developing five storm-time empirical models of the ionosphere with ionospheric total electron content (TEC) as dependent variable, and each of the five solar proxies as the independent variable. As the energy from the Sun differs from one latitudinal region to another on Earth, two locations at different latitudes were considered for the analysis. Based on their long data coverage periods, Hartebeesthoek (HRAO, geographic coordinates: 25.89° S, 27.69° E; geomagnetic coordinates: 36.32° S, 94.69° E), South Africa; and Mbarara (MBAR, geographic coordinates: &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;60&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; S and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;30&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;74&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; E, geomagnetic coordinates: &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;22&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; S and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;102&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;36&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; E), Uganda, were chosen to represent the middle and low latitude ionospheric regions, respectively. Their data coverage periods are 27 September 1996 to 30 March 2024 (HRAO) and 17 July 2001 to 30 March 2024 (MBAR) and only storm-time TEC data within these periods selected based on the criterion &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mo&gt;⩽&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;50&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; nT or &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;⩾&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; were considered for the statistical analysis. Through PCA decomposition, TEC data were broken up into a matrix of principal directions of the maximum variances in the dataset (or matrix of eigenvectors of the covariance matrix) and a matrix of principal components (PCs) which represent the projection of data onto the principal directions. For each model, PCs were thereafter modelled in terms of the corresponding solar activity index and the modelled quantities were further combined with the original PC vectors to get the reconstructed TEC for the entire period of the stu","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106477"},"PeriodicalIF":1.8,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704494","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":"A decline of linear relation between outgoing longwave radiation and temperature during geomagnetic disturbances","authors":"A.A. Karakhanyan,&nbsp;S.I. Molodykh","doi":"10.1016/j.jastp.2025.106503","DOIUrl":"10.1016/j.jastp.2025.106503","url":null,"abstract":"<div><div>Climate modeling is the main instrument to predict future climate changes. Despite the recent advances in this field, there is still high uncertainty concerning the contribution of natural (including solar/geomagnetic activity) and anthropogenic factors to the current climate changes. Based on the observational data, we studied the linear relation between Outgoing Longwave Radiation (OLR) and Near-Surface Temperature (NST) under quiet and disturbed geomagnetic conditions 1979 through 2022. Water vapor (due to its optical properties) was established to be the main factor to cause a linear OLR-NST relation. The OLR-NST correlation in the optically thin atmosphere above 30° corresponds to quiet geomagnetic conditions and so does the anticorrelation between the above parameters in the optically thick low-latitude atmosphere. The winter ocean regions of the OLR-NST anticorrelation up to 60° in the both hemispheres under quiet geomagnetic conditions related to the clouds. We found the geomagnetic disturbances lead to decrease in the OLR response to the NST variations in the optically thin atmosphere within the mid- and high latitudes, particularly during spring. The considerable changes of linear OLR-NST relation are observed in the optically thick low-latitude atmosphere during geomagnetic disturbances.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"270 ","pages":"Article 106503"},"PeriodicalIF":1.8,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704427","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}