Journal of Atmospheric and Solar-Terrestrial Physics最新文献

{"title":"Spatio-temporal variations of lightning activity over Nepal's complex terrain: Links to altitude and meteorological factors","authors":"Pradip Karki ,&nbsp;Shriram Sharma ,&nbsp;Rupraj Biswasharma ,&nbsp;Sunil D. Pawar ,&nbsp;V. Gopalkrishnan ,&nbsp;Madhu Gyawali ,&nbsp;Khem Narayan Poudyal","doi":"10.1016/j.jastp.2025.106615","DOIUrl":"10.1016/j.jastp.2025.106615","url":null,"abstract":"<div><div>This study investigates the diurnal and seasonal variations of lightning activity over the complex terrain of Nepal, which spans elevations from 59 m to 8848 m above sea level. Despite lightning being a leading weather-related hazard in Nepal, causing over 100 fatalities annually, the altitudinal distribution of lightning has received limited attention. We use lightning data from the GLD360 network and meteorological parameters from the ERA5 reanalysis to analyze the influence of Convective Available Potential Energy (CAPE), wind, temperature, humidity, and cloud structure on lightning activity. Results reveal a strong altitudinal gradient in lightning flash density (FD), with maxima in the southern foothills and significant decrease toward higher elevations. Temporally, lightning exhibits two prominent peaks: one in the afternoon and the other around midnight. Afternoon lightning in the higher elevations is associated with surface heating, upslope winds, increased CAPE and moisture convergence, whereas nocturnal lightning over foothills is linked to persistent CAPE and downslope (katabatic) wind convergence. Cloud base height (CBH) further supports this spatial and temporal convection shift. Correlation analyses show strong FD–CAPE–humidity relationships in the foothills that weaken with elevation, suggesting increasing influence of orographic and microphysical processes aloft. The ratio of negative to positive CG flashes increases with elevation, likely influenced by CBH. Vertical profiles of ice water content and vertical velocity reinforce a clear transition from nocturnal convection in the southern plains to thermally and topographically driven daytime convection in the northern mountains. This study highlights how terrain modulates convective regimes and lightning variability across Nepal.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"277 ","pages":"Article 106615"},"PeriodicalIF":1.9,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145097854","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":"Numerical simulation study on high temporal resolution variation characteristics of atmospheric limb infrared radiation under aurora disturbance","authors":"Fan Wu ,&nbsp;Congming Dai ,&nbsp;Cong Zhang ,&nbsp;Wentao Lian ,&nbsp;Shunping Chen ,&nbsp;Heli Wei","doi":"10.1016/j.jastp.2025.106614","DOIUrl":"10.1016/j.jastp.2025.106614","url":null,"abstract":"<div><div>Auroral disturbances can significantly enhance atmospheric limb infrared radiance in near space by several orders of magnitude, impacting space-based systems. This study used infrared radiance data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite during the 2003 “Halloween Storm” to estimate the accuracy of the Strategic High-Altitude Radiance Code (SHARC) model under both quiet and auroral conditions. The average relative error of the SHARC simulations compared to the SABER measurements ranged from 11.8 to 19.4 %, indicating a reliable agreement with the observations. Due to the limited temporal resolution of satellite observations at fixed locations, SHARC was further used to simulate hourly variations in 4.3 and 5.3 μm infrared radiance over high-latitude regions (50–200 km) during the storm. The results showed that auroral disturbances enhanced the 4.3 μm radiance by up to two orders of magnitude, particularly above 130 km during the day and above 110 km at night. The 5.3 μm radiance was also enhanced, with peak increases of about one order of magnitude near 120 km. The study also analyzed the temporal evolution of key excited-state species (NO, CO₂, and NO⁺), identifying their respective roles in infrared enhancement. Finally, the uncertainties in the SHARC simulations and SABER measurements were discussed, confirming the applicability of SHARC under auroral conditions and clarifying the differing enhancement mechanisms of the two bands.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"276 ","pages":"Article 106614"},"PeriodicalIF":1.9,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144908150","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":"Absorbing and scattering aerosols over semi-arid region in India: Temporal variation and possible sources","authors":"Pawan S. Soyam ,&nbsp;Pramod D. Safai ,&nbsp;Shivdas Bankar ,&nbsp;Kiran Todekar ,&nbsp;Neelam Malap ,&nbsp;Sunil Kondle ,&nbsp;Pradeep Zambare ,&nbsp;Mahendra Mane ,&nbsp;Sanjay S. Kale ,&nbsp;Thara Prabhakaran","doi":"10.1016/j.jastp.2025.106613","DOIUrl":"10.1016/j.jastp.2025.106613","url":null,"abstract":"<div><div>This research article investigates the diurnal and seasonal characteristics of aerosol optical properties such as absorbing and scattering coefficients and single scattering albedo (SSA) over the semi-arid region of Solapur (17°43′45.4332″ N, 75°.51′24.4476″ E, 457 m AMSL), India. These aerosol optical properties play a crucial role in understanding the aerosol radiative forcing and thereby the climate impact of atmospheric aerosols. However, there is a lack of comprehensive studies focusing on the temporal dynamics of aerosol optical properties in peninsular India especially from the arid region. To address this gap, we conducted multiyear (July 2019 to October 2022) measurement campaign to characterize the aerosol optical properties at Solapur. Our findings reveal significant temporal variations in the aerosol optical properties on the diurnal, seasonal, and annual scales. Diurnally, the aerosol optical properties showed distinct patterns, with higher absorption and scattering coefficients during daytime due to increased anthropogenic activities and local emissions. Seasonally, the aerosol loading was influenced by changes in the prevailing meteorological conditions, including aerosol scavenging due to the monsoonal influences and regional transport of aerosols. The intra-annual variability suggested the possible influence of various factors such as changes in local emissions, land use patterns, and local boundary layer conditions. Furthermore, the SSA values showed slight annual variation, with maximum values in post monsoon and minimum during monsoon period. SSA value (mean 0.71 ± 0.02 and median 0.73 ± 0.03) indicated towards significant role of absorbing aerosols in aerosol radiative forcing and thereby atmospheric warming over this semi-arid location.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"275 ","pages":"Article 106613"},"PeriodicalIF":1.9,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144892807","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 of Sunspots on full-disk continuum images using the MiniMax Optimization and Feature Extraction","authors":"Madhan Veeramani,&nbsp;Sudhakar M.S.","doi":"10.1016/j.jastp.2025.106605","DOIUrl":"10.1016/j.jastp.2025.106605","url":null,"abstract":"<div><div>Novel contributions engaging white and black-box models for Sunspot detection neglect optimization which is highly essential in solar activity monitoring. This demanded the quest for automated mathematical programming methods, warranting accurate forecasting of solar activity. Accordingly, in this paper, an energy-optimized adaptive curve fitting sunspot detection model coined Sunspot Attribute Extraction via Energy-tuned Minimax Optimization (SAEEMO) is introduced for characterizing diverse solar constituents followed by feature extraction from full disk images. SAEEMO initially considers the overall image energy as the sum of energies concerned with the solar disk to distinguish the solar variations that are intensity enhanced, facilitating segmentation. Later, the Sunspots are further disintegrated into umbra and penumbra, characterized as edge sensitivity and regularization terms, and adaptively thresholded using the novel energy-based Minimax optimizer. The adopted energy function packs the intensity variations within the Minimax bounds to render a globally optimal solution in an iterative manner using the line search operation. SAEEMO’s Receiver Operating Characteristics (ROC) investigation on Helioseismic and Magnetic Imager (HMI) continuum images obtained from Solar Dynamics Observatory (SDO) reveals its preservative and distinctive nature in detecting and characterizing diverse solar features. Also, relative investigations of the extracted solar features with the catalogs of Debrecen Photoheliographic Data (DPD), Heliophysics Feature Catalog (HFC), Sunspot Index and Long-term Solar Observations (SILSO), and Space Weather Prediction Center (SWPC) demonstrate SAEEMO’s consistency.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"275 ","pages":"Article 106605"},"PeriodicalIF":1.9,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879497","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":"Forecasting near-surface air temperature via SARIMA and LSTM: A regional time-series study","authors":"Muhammed M. Aksoy ,&nbsp;Md. Najmul Mowla ,&nbsp;Mehmet Bilgili ,&nbsp;Engin Pinar ,&nbsp;Tahir Durhasan ,&nbsp;Davood Asadi","doi":"10.1016/j.jastp.2025.106604","DOIUrl":"10.1016/j.jastp.2025.106604","url":null,"abstract":"<div><div>Accurate modeling of near-surface air temperature (AT) trends is critical for assessing global and regional climate risks, particularly in light of the intensifying warming signals observed across the northern hemisphere and the tropics. This study proposes a robust and computationally efficient framework for forecasting near-surface AT across the global, the northern hemisphere, the southern hemisphere, and the tropics using two complementary time-series modeling techniques: seasonal autoregressive integrated moving average (SARIMA) and long short-term memory (LSTM) networks. The models are trained to capture both structured seasonal patterns and nonlinear temporal dynamics by leveraging the ERA5 reanalysis dataset (1970–2024) and incorporating preprocessing steps such as detrending and Z-score normalization. SARIMA consistently outperformed LSTM across most domains, particularly in the global region, achieving lower RMSE (0.0967 °C) and higher correlation (R = 0.9975), reflecting its superior capacity for linear and seasonal signal extraction. Quantitatively, SARIMA demonstrates 5%–10% lower RMSE and slightly higher correlation than LSTM across all domains, underscoring the statistical significance of its performance advantage. Projected near-surface AT anomalies by 2050 reveal a marked warming trend, with the SARIMA model estimating a global anomaly of +1.078 °C and a northern hemisphere anomaly of +1.474 °C, closely aligning with IPCC-reported trajectories and exceeding CMIP5 RCP4.5 projections. The findings underscore SARIMA’s reliability for short- to mid-term near-surface AT forecasting and LSTM’s potential for future hybrid modeling schemes. This work fills a critical methodological gap by integrating statistical rigor with scalable deep learning, offering enhanced fidelity for regional climate adaptation planning.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"275 ","pages":"Article 106604"},"PeriodicalIF":1.9,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879441","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":"Ionospheric TEC prediction in low-latitude Indian region during geomagnetic storm periods based on XGBoost with optuna framework and comparison with IRI-Plas 2020","authors":"T. Muthukumaran ,&nbsp;R. Mukesh ,&nbsp;S. Kishore Kumar ,&nbsp;Andrew F. Jude ,&nbsp;J. Kenisha ,&nbsp;G. Cynthia ,&nbsp;S. Logesh ,&nbsp;Sarat C. Dass ,&nbsp;S. Kiruthiga","doi":"10.1016/j.jastp.2025.106606","DOIUrl":"10.1016/j.jastp.2025.106606","url":null,"abstract":"<div><div>This paper introduces a strong 24-h TEC forecast model based on the Extreme Gradient Boosting (XGBoost) algorithm, implemented for GPS-based TEC data at both the IISC and Chum stations. For a better tuning of the model's performance, two hyperparameter tuning approaches—Optuna and Hyperopt—were utilized. The assessment pertains to five primary GS events: the Halloween Storm (2003), St. Patrick's Day Storm (2015), the February 2022 Mother's Day Storm (2024), and yet another GS in 2024. The AI model forecasts were compared against the IRI-PLAS 2020 empirical model on the basis of standard performance measures such as Root Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE), and Mean Squared Logarithmic Error (MSLE). Results show that the Optuna-tuned XGBoost model always performed better than the IRI-PLAS 2020 model for all GS events. RMSE values for Optuna were considerably lower: 4.7254 for the Halloween Storm versus 8.7335 using IRI-PLAS, 2.8389 versus 17.4692 for St. Patrick's Day, 4.4167 versus 9.9611 for the 2022 storm, 10.8861 versus 16.4781 for the Mother's Day event, and 12.8778 versus 29.8309 for the second 2024 storm. For comparison, the XGBoost model optimized using Hyperopt, tested over the same events, had RMSEs of 14.52, 7.01, 5.19, 6.80 and 14.97, respectively. While Hyperopt outperformed the IRI-PLAS model in each scenario, Optuna produced the best results overall. These results confirm the effectiveness of machine learning, specifically the XGBoost model optimized using Optuna tuning, in observing intricate TEC dynamics during geomagnetic disturbances. The research points out how AI-driven forecasting can dramatically enhance space weather resilience by limiting error in prediction and providing more trustworthy GNSS and communication system functionality under high-impact solar activity.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"275 ","pages":"Article 106606"},"PeriodicalIF":1.9,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144858038","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":"Novel real-time detection method of cycle slips using ultra-high rate GNSS observations in urban environments","authors":"Shengyue Ji ,&nbsp;Qixiang Peng ,&nbsp;Ying Xu ,&nbsp;Jing Wang ,&nbsp;Duojie Weng ,&nbsp;Wu Chen ,&nbsp;Huan Luo","doi":"10.1016/j.jastp.2025.106600","DOIUrl":"10.1016/j.jastp.2025.106600","url":null,"abstract":"<div><div>The use of Global Navigation Satellite Systems (GNSS) for precise navigation and positioning using Real-Time Kinematic (RTK) or Precise Point Positioning (PPP) techniques has gained popularity in urban environments. However, the performance of GNSS in urban areas is significantly affected by cycle slips caused by multipath reflections from high-rise buildings. Detecting cycle slips accurately becomes a primary challenge for achieving reliable RTK or RTPPP solutions in urban settings. Traditional methods for cycle slip detection often fall short due to the detrimental effects of multipath interference.</div><div>This research aims to detect cycle slips utilizing ultra-high rate GNSS observations. We conducted an analysis of these observations and discovered that they exhibit reduced variation in observation noise and multipath compared to commonly used 1 Hz observations. Leveraging this insight, we propose a novel cycle slip detection method that eliminates coordinate parameters from the geometry-based mathematical model. Instead, it incorporates only a single parameter related to the receiver clock, enhancing its robustness against multipath effects.</div><div>Our proposed approach leverages the favorable characteristics of ultra-high rate GNSS observations. By excluding coordinate parameters and focusing solely on the receiver clock parameter, our method becomes more resilient to the impacts of multipath interference. This novel methodology offers improved cycle slip detection capabilities compared to traditional methods.</div><div>To evaluate the effectiveness of our method, we performed numerical experiments using 50 Hz GNSS observations, including scenarios in urban environments. Remarkably, our new method achieved an almost perfect success rate of cycle slip detection, nearing 100 %. These results demonstrate the efficacy of our approach, even in challenging urban settings.</div><div>The findings of this research present a significant advancement in cycle slip detection using ultra-high rate GNSS observations. By reducing the reliance on coordinate parameters and considering the unique characteristics of these observations, our method holds promise for enhancing the reliability and accuracy of GNSS positioning, particularly in urban environments. Numerical test shows that all those cases can be detected with traditional method, can also be detected with the new method.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"275 ","pages":"Article 106600"},"PeriodicalIF":1.9,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852905","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 impacts of planetary boundary layer schemes on maximum potential intensity of idealized tropical cyclone","authors":"Chen Chen ,&nbsp;Jiangnan Li","doi":"10.1016/j.jastp.2025.106603","DOIUrl":"10.1016/j.jastp.2025.106603","url":null,"abstract":"<div><div>Tropical cyclones (TCs)' development relies on boundary layer processes. With climate change increasing extreme TCs, predicting their intensity under different planetary boundary layer (PBL) schemes is crucial. This study utilizes idealized TC experiments at cloud-resolving resolution within the Weather Research and Forecasting (WRF) model, employing PBL schemes of low-order or high-order closure, and local or nonlocal types, to investigate the impacts of these schemes on TC's maximum potential intensity (MPI).</div><div>The findings indicate that the MPI is remarkably sensitive to the choice of PBL schemes, with disparities in simulated MPI reaching up to 67 hPa. While schemes with different closure methods often compute turbulent diffusion coefficients differently, some, like YSU and MYNN3, simulate similar MPI due to shared low boundary layer heights (PBLH) and efficient latent heat utilization. Conversely, schemes with similar diffusion coefficient definitions, such as MYNN3 and BouLac, can produce differing MPI due to variations in mixing mechanisms.</div><div>Analysis of strong versus weak TC simulations reveals that strong TCs have lower boundary layer heights and turbulent diffusion coefficient peaks further from the surface, leading to greater near-surface gradient wind imbalance and stronger radial inflow. Weak TCs, on the other hand, have higher boundary layer heights and peaks closer to the surface, resulting in weaker inflow. Stronger inflow in strong TCs promotes moisture convergence in the core region, enhancing inner-core diabatic heating and forming a pronounced upper-level warm core, which accelerates TC intensification. The study highlights how PBL schemes significantly affect TC MPI by linking dynamic and thermodynamic processes.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"274 ","pages":"Article 106603"},"PeriodicalIF":1.9,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144772713","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":"Spatial risk assessment of tropical cyclone for disaster mitigation in a coastal district of India using geospatial technology","authors":"Brinda Banerjee ,&nbsp;Priyanka Karmakar ,&nbsp;Sudhir Kumar Singh ,&nbsp;Dharmaveer Singh ,&nbsp;Biswajit Patra ,&nbsp;T.P. Singh ,&nbsp;Somil Swarnkar","doi":"10.1016/j.jastp.2025.106602","DOIUrl":"10.1016/j.jastp.2025.106602","url":null,"abstract":"<div><div>Frequent cyclones in the Bay of Bengal (BoB) cause substantial loss to property and human lives. This asserts for the systematic vulnerability assessment to mitigate their adverse impact. Odisha is one of the most vulnerable states in India exposed to the tropical cyclones. Most of the studies related to tropical cyclone risk mapping and identification of evacuation route in Odisha are limited at scale greater than district level. This study investigated risk of the tropical cyclone Yaas in the Balasore district of Odisha (India) at block level using Fuzzy Analytical Hierarchical Process (FAHP) and Geographic Information System (GIS) based spatial analysis methods. A total number of 15 parameters classified under physical (6), social (6) and mitigation (3) were used for this purpose. The weight of these parameters was determined using FAHP. However, categorization of weights into the high, medium and low was performed using a Weighted Overlay Analysis (WOA). Further, a spatial vulnerability risk map was generated by dividing the multiplication of physical and social vulnerability indices with that of the mitigation capacity. Analysis of results show that about 44.6 % and 49.3 % of study area are covered under the category of the ‘high’ and ‘moderate’ risks, respectively, while ∼6 % under the ‘low’ risk category. The high-risk zones are predominantly situated in the western, south-western, central and eastern regions of the study area. These are not only close to the cyclone track and coastlines but also have revealed poor mitigation capacity. Additionally, network analysis was used to determine the evacuation routes (shortest route path) from the outlets/settlements to the cyclone shelters based on the developed risk map. These spatial data (e.g., vulnerability risk map and evacuation routes) can be used by district's emergency administration and management authorities to develop efficient cyclone mitigation plans in the Balasore district. Thus, the study has demonstrated methodological robustness through the integration of FAHP and geospatial techniques in spatial risk assessment for the tropical cyclone at district level.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"274 ","pages":"Article 106602"},"PeriodicalIF":1.9,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144772711","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":"Evolution and decay of a stable and a dynamic airglow patch","authors":"Nina K. Eriksen ,&nbsp;Yukitoshi Nishimura ,&nbsp;Matthew Zettergren ,&nbsp;Dag A. Lorentzen ,&nbsp;Kjellmar Oksavik ,&nbsp;Lisa J. Baddeley ,&nbsp;Keisuke Hosokawa ,&nbsp;Kazuo Shiokawa ,&nbsp;Leslie Lamarche ,&nbsp;Mark E. Redden ,&nbsp;Asti Bhatt","doi":"10.1016/j.jastp.2025.106593","DOIUrl":"10.1016/j.jastp.2025.106593","url":null,"abstract":"<div><div>This study investigates the evolution of two polar cap airglow patches, AGP1 and AGP2, observed over Resolute Bay in northern Canada. AGP1 exhibited stable shape, followed the ExB drift patterns and maintained high electron density as it transited toward the auroral oval, sustaining the maximum F-region density and redline emissions by a downward vertical drift. An initial non-uniform density decay was observed in AGP1’s density profile; the topside shifted downwards, resulting in increased bottomside density. Later, the maximum and bottomside density started to decay. Overall, the downflow contributed to a faster density decay. In contrast, AGP2 displayed dynamic characteristics, halting its motion mid-polar cap, followed by a prolonged decay in both electron density and redline emission. Observations and GEMINI simulations revealed that recombination between atomic ions and neutral molecules was the dominant mechanism for density decay in the optical layer. The decay rate was affected by vertical drift, magnetic field line orientation, and local neutral atmosphere conditions, which may be influenced by prior patch activity. Simulations of AGP1 using GEMINI and GLOW highlight the importance of vertical ExB drift in sustaining electron density maximum and redline emission intensity. By using various free parameters in the model to tune our simulations (e.g. background precipitation) we are able to achieve reasonable agreement with observed patch behavior. Our findings emphasize the interplay between vertical drift, recombination rates, and neutral wind in determining polar cap patch evolution, as well as the complexity of patch dynamics and their dependence on local ionospheric and atmospheric conditions.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"275 ","pages":"Article 106593"},"PeriodicalIF":1.9,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852868","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}