Journal of Atmospheric and Solar-Terrestrial Physics最新文献_第9页

Tropical cyclones as a possible source of lower ionosphere (thermosphere) perturbation: a case study of Amphan Super Cyclone (SuCS) over Bay of Bengal 热带气旋作为低层电离层（热层）扰动的可能来源：孟加拉湾Amphan超级气旋（SuCS）的个案研究

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-10-09 DOI: 10.1016/j.jastp.2025.106654

Omkar M. Patil , Debarchan Kar , Navin Parihar , Rajesh Singh , A.P. Dimri

The study investigates Super Cyclone (SuCS) Amphan, which occurred over the Bay of Bengal (BoB) during 16–21 May 2020 as a possible source of lower ionospheric perturbations. INSAT-3D satellite observations confirmed intense convective activity through low Cloud Top Brightness Temperature (∼–80 °C) and suppressed Outgoing Longwave Radiation (below 100 W/m²). Lightning analysis indicated an increase in activity within 500 km of the cyclone center, with cloud-to-cloud (CC) lightning intensifying in the eyewall during the cyclone's peak. Over 60 % of positive CC flashes exceeded 10 kA, highlighting strong convective electrical dynamics. Temperature perturbations observed by the AIRS instrument onboard NASA's Aqua satellite appeared as concentric wave patterns at stratospheric altitudes, indicating atmospheric gravity waves (AGWs) activity in the northeast of the storm center. SABER temperature profiles further revealed enhanced wave amplitudes from May 17–20, confirming AGW propagation into the mesosphere-lower thermosphere (MLT) region. Nightglow emissions observed by the Suomi-NPP/DNB sensor provided additional evidence of concentric gravity waves at the MLT heights. This enhanced AGW activity coincided with Amphan's intensification. This multi-altitude observational analysis highlights the role of intense convection and lightning in AGW generation and their subsequent influence on upper atmospheric dynamics. The observations confirm that tropical cyclones serve as a source of lower ionospheric disturbances through AGW-driven energy and momentum deposition.

该研究调查了2020年5月16日至21日在孟加拉湾（BoB）发生的超级气旋（SuCS） Amphan，它可能是电离层扰动的一个来源。INSAT-3D卫星观测通过低云顶亮温（~ -80℃）证实了强烈的对流活动，并抑制了传出长波辐射（低于100 W/m2）。闪电分析显示，气旋中心500公里范围内的活动有所增加，在气旋高峰期，眼壁上的云对云（CC）闪电加剧。超过60%的正CC闪光超过10ka，突出了强对流电动力学。美国宇航局Aqua卫星上的AIRS仪器观测到的温度扰动在平流层高度表现为同心波模式，表明风暴中心东北部的大气重力波（AGWs）活动。SABER温度剖面进一步显示，5月17日至20日的波幅增强，证实AGW传播到中层-低层热层（MLT）区域。由Suomi-NPP/DNB传感器观测到的夜光辐射提供了在MLT高度存在同心圆重力波的额外证据。AGW活性的增强与Amphan的增强相一致。这种多高度观测分析强调了强对流和闪电在AGW产生中的作用及其随后对高层大气动力学的影响。观测结果证实，热带气旋通过agw驱动的能量和动量沉积，是低层电离层扰动的一个来源。

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引用次数: 0

Long-term projections of global, northern hemisphere, and arctic sea ice concentration using statistical and deep learning approaches 使用统计和深度学习方法的全球、北半球和北极海冰浓度的长期预测

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-09-20 DOI: 10.1016/j.jastp.2025.106634

Mehmet Bilgili , Engin Pinar , Md. Najmul Mowla , Tahir Durhasan , Muhammed M. Aksoy

The accelerating decline in sea ice concentration (SIC) poses significant challenges for global climate regulation, maritime navigation, and arctic ecosystem stability. This study develops and evaluates two advanced time-series forecasting models, seasonal autoregressive integrated moving average (SARIMA) and long short-term memory (LSTM) networks, to project SIC trends through 2050 across three spatial domains: the globe, the northern hemisphere, and the arctic. Utilizing the ERA5 reanalysis dataset (1970–2024) from the European center for medium-range weather forecasts (ECMWF), the models capture seasonal cycles and complex temporal dependencies to enable robust long-term projections. Comparative analysis demonstrates that SARIMA effectively models periodic fluctuations, while LSTM excels at learning nonlinear dependencies inherent in SIC dynamics. Performance metrics, including mean absolute percentage error (MAPE), root mean square error (RMSE), and correlation coefficient (R), confirm the high accuracy of both models, with SARIMA showing superior capability in representing structured seasonal patterns. Projections indicate a persistent decline in SIC, with arctic concentrations decreasing from 55.60% in 2023 to approximately 46.84% by 2050, underscoring the pronounced effects of arctic amplification. These results provide valuable insights for climate modeling, arctic policy formulation, and the development of adaptive navigation strategies in a rapidly changing polar environment.

海冰浓度的加速下降对全球气候调节、海上航行和北极生态系统的稳定提出了重大挑战。本研究开发并评估了两个先进的时间序列预测模型，即季节自回归综合移动平均（SARIMA）和长短期记忆（LSTM）网络，以预测到2050年全球、北半球和北极三个空间域的SIC趋势。利用欧洲中期天气预报中心（ECMWF）的ERA5再分析数据集（1970-2024），这些模式捕捉季节周期和复杂的时间依赖性，从而实现可靠的长期预测。对比分析表明，SARIMA有效地模拟了周期波动，而LSTM在学习SIC动力学中固有的非线性依赖方面表现出色。包括平均绝对百分比误差（MAPE）、均方根误差（RMSE）和相关系数(R)在内的性能指标证实了两种模型的高准确性，其中SARIMA在表示结构化季节模式方面表现出卓越的能力。预估表明SIC持续下降，北极浓度从2023年的55.60%下降到2050年的约46.84%，强调了北极放大的显著影响。这些结果为气候建模、北极政策制定以及在快速变化的极地环境中自适应导航策略的发展提供了有价值的见解。

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引用次数: 0

Centennial solar EUV irradiance from ionospheric currents: Varying sunspot-EUV irradiance relation and modified spot-facula ratio 电离层电流的百年太阳EUV辐照度：变化的太阳黑子-EUV辐照度关系和修正的黑子-光斑比

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-10-17 DOI: 10.1016/j.jastp.2025.106653

K. Mursula

Sunspots offer a uniquely long view of solar magnetic activity, and depict large variability during the last 100 years, a period known as the Modern Maximum (MM). However, if our view of solar variability was only based on the strongest magnetic fields, it would be incomplete. Therefore, other variables are needed to study the long-term evolution, e.g., of weaker magnetic fields and the different radiative emissions. Recently, the relation between sunspots and several other solar activity proxies like the F10.7 and F30 radio fluxes and the MgII index (all proxies of EUV irradiance) was found to vary during the last 70 years so that a relative sunspot dominance over EUV in the 1950s–1960s changed to EUV dominance in the 2000s (Mursula et al., 2024). Here we use data from eight long-operating observatories to calculate the yearly range of daily variation of the geomagnetic Y-component, the rY index, for the last 137 years. We show that the rY index correlates extremely well with the MgII index and the solar F30 radio flux. These three indices have no trend relative to each other over the respective intervals. On the other hand, the F10.7 flux has a significant trend with respect to the three co-varying EUV indices (MgII, F30, rY). Therefore, the rY index replaces F10.7 as the best long-term EUV proxy, and extends the MgII index by 90 years. We verify that all the four EUV proxies (rY, MgII, F30, F10.7) have an increasing trend with respect to sunspots during the last 50–70 years. This is valid both for sunspot numbers and group numbers. Extending this earlier with the rY index, we find that the relation between EUV irradiance and sunspots has a nonlinear, quadratic evolution over the MM. This implies that the Sun has more sunspots relative to EUV irradiance during the growth and maximum of the MM, while the opposite is true during its decay and minimum. We estimate that the MgII index (solar EUV irradiance) increases by 24% of its solar cycle variation with respect to the sunspot number during the last 70 years. Our results indicate a systematic difference in the evolution between sunspots (generally: photosphere) and plages (generally: chromosphere) with long-term solar activity. The implied varying spot-facula ratio has consequences to the stellar evolution of the Sun and Sun-like stars.

太阳黑子提供了一个独特的太阳磁活动的长期视图，并描绘了过去100年的大变化，这一时期被称为现代极大期（MM）。然而，如果我们对太阳变化的看法仅仅基于最强的磁场，那将是不完整的。因此，需要其他变量来研究长期演变，例如，较弱的磁场和不同的辐射发射。最近，太阳黑子与其他几个太阳活动指标(如F10.7和F30射电通量以及MgII指数（所有EUV辐照度的指标）之间的关系在过去70年中发生了变化，因此，20世纪50年代至60年代太阳黑子对EUV的相对优势转变为21世纪初的EUV优势（Mursula et al., 2024）。在这里，我们使用八个长期运行的观测站的数据来计算过去137年来地磁y分量（y指数）的日变化的年范围。我们发现rY指数与MgII指数和太阳F30射电通量的相关性非常好。这三个指数在各自的区间内没有相互的趋势。另一方面，F10.7通量相对于三个共变EUV指数（MgII、F30、rY）有显著的变化趋势。因此，rY指数取代F10.7成为最佳的长期EUV指标，并将MgII指数延长90年。我们验证了在过去50-70年间，所有四个EUV代理（rY, MgII, F30, F10.7）在太阳黑子方面都有增加的趋势。这对太阳黑子数和群数都是有效的。用rY指数扩展这一点，我们发现EUV辐照度和太阳黑子之间的关系在MM上具有非线性的二次演化。这意味着在MM的增长和最大值期间，太阳相对于EUV辐照度有更多的太阳黑子，而在其衰减和最小值期间则相反。我们估计，在过去70年中，MgII指数（太阳EUV辐照度）相对于太阳黑子数的太阳周期变化增加了24%。我们的研究结果表明，太阳黑子（通常是光球层）和太阳黑子（通常是色球层）在长期太阳活动中的演化存在系统差异。暗变的斑光斑比对太阳和类太阳恒星的演化有影响。

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引用次数: 0

A ground state of the geospace on November 6–7, 2009 2009年11月6日至7日地球空间的地面状态

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-10-10 DOI: 10.1016/j.jastp.2025.106659

Yongliang Zhang, Jesper W. Gjerloev, Larry J. Paxton, Robert Schaefer, Matt Friel

We introduce a new criterion: A ground state of the geospace (the magnetosphere, ionsophere and thermosphere) where all of three regions are undisturbed by the impact of the solar wind particle, energy, and momentum inputs. It is challenging to find such days when the impact is minimized and the geospace is at its ground state (super quiet) or undisturbed condition. After a search of databases of SuperMAG SME index and DMSP SSUSI aurora data over two decades (2002–2022), we identified a few rare super quiet intervals using two criteria: (1) A very low geomagnetic activity (AE or SME <50 nT, SmH >0 nT), and (2) a very weak auroral activity with auroral oval above 70° magnetic latitude and N₂ Lyman-Birge-Hopfield Short (LBHS, 140–150 nm) auroral intensity below 500 R, over 48 consecutive hours or longer. Here we report one super quiet interval (November 6–7, 2009). This interval occurred during the deep solar minimum with daily F10.7 around 70. The low auroral intensity (particle precipitation) and coincident weak plasma convection indicates low ionospheric density and Joule/particle heating at high latitudes. This super quiet condition leads to an undisturbed thermosphere: without any O/N₂ depletion or nitric oxide (NO) enhancement at high latitudes. The super quiet interval was driven by a long (∼61 h), steady and weak solar wind (velocity ∼300 km/s, dynamic pressure 1–2 nPa) and a northward IMF (Interplanetary Magnetic Field) B_z (0–4 nT). These solar wind driving conditions lead to a near zero solar wind-magnetosphere coupling rate and to what we refer as a “geospace ground state”.

我们引入了一个新的标准：地球空间（磁层、电离层和热层）的基态，其中所有三个区域都不受太阳风粒子、能量和动量输入的影响。很难找到这样的日子，当影响最小化，地球空间处于基态（超安静）或不受干扰的状态。通过对SuperMAG SME指数和DMSP SSUSI近20年（2002-2022）极光数据的检索，我们发现了一些罕见的超安静间隔，使用了两个标准：(1)极低的地磁活动（AE或SME <；50 nT, SmH >0 nT）和(2)极弱的极光活动，极光椭圆在70°磁纬以上，N2 lyman - birg - hopfield Short （LBHS, 140-150 nm）极光强度低于500 R，连续48小时或更长。这里我们报告了一个超级安静的间隔（2009年11月6日至7日）。这个间隔发生在太阳深层极小期，日F10.7在70左右。低极光强度（粒子降水）和同时发生的弱等离子体对流表明高纬度地区电离层密度低，焦耳/粒子加热。这种超安静的条件导致了一个不受干扰的热层：在高纬度地区没有任何O/N2消耗或一氧化氮（NO）增强。超安静期是由长（~ 61 h）、稳定和微弱的太阳风（速度~ 300 km/s，动压1 ~ 2 nPa）和向北的IMF（行星际磁场）Bz （0 ~ 4 nT）驱动的。这些太阳风驱动条件导致太阳风-磁层耦合率接近于零，也就是我们所说的“地球空间基态”。

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引用次数: 0

Mean-field dynamo and forecasting of solar activity 平均场发电机与太阳活动预报

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-11-04 DOI: 10.1016/j.jastp.2025.106673

Vladimir Obridko , Antonina Shibalova , Dmitry Sokoloff , Ilya Livshits

According to the generally accepted theory, the field of local active areas arises from the poloidal magnetic field. The field in the polar regions, which is measured directly by magnetographs, can be a proxy for the latter. It has been shown that the mean-field dynamo is undoubtedly the main mechanism that generates solar activity and the 11-year cycle. However, the magnetic flux generated in the dynamo, although it is the genetic basis of solar activity, still does not allow us to unambiguously connect the characteristics of the magnetic field with other indices of solar activity, including the best known indicator, the number of sunspots. Magnetic fields of active regions and spots are formed from the mean magnetic flux. Its most important properties are the threshold nature and the preservation of the full flux. This is why a completely reliable long-term SSN forecast is possible after the occurrence of an equatorial wave approximately 18 months before the maximum. The processes in leptocline play a decisive role in this case.

根据普遍接受的理论，局部活动区的磁场是由极向磁场产生的。磁力计直接测量的极地磁场可以作为后者的代表。研究表明，平均场发电机无疑是产生太阳活动和11年周期的主要机制。然而，发电机中产生的磁通量虽然是太阳活动的遗传基础，但仍然不能使我们明确地将磁场的特征与太阳活动的其他指标联系起来，包括最著名的指标，太阳黑子的数量。活动区和黑子的磁场由平均磁通量形成。其最重要的性质是阈值性和保持全通量。这就是为什么在赤道波发生前大约18个月，一个完全可靠的长期SSN预报是可能的。瘦斜的过程在这种情况下起决定性作用。

引用次数: 0

Analysis of ozone pollution characteristics and meteorological factors in Yichang City, Hubei 湖北宜昌市臭氧污染特征及气象因子分析

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-10-24 DOI: 10.1016/j.jastp.2025.106668

Ting Zhou , Hui Hu , Pan Wang , Mi Zhang , Haoqi Wen , Dan Liu , Wei Liu

Grasping the local ozone pollution characteristics and associated meteorological factors is of great significance for scientific support for ozone (O₃) pollution prevention. O₃ concentrations and related meteorological data from 2020 to 2022 Yichang City, Hubei were analyzed for exploring the spatiotemporal distribution of O₃ concentrations and the impact of associated meteorological factors. The results revealed that O₃ pollution in Yichang from 2020 to 2022 exhibited a clear trend of the increasing pollution severity and frequency. High incidences of ozone pollution was between May and September (mainly in summer), but high concentrations of precursors (NO₂ and TVOCs) appeared from November to January (mainly in winter), highlighting the decisive role of meteorological conditions in the ozone formation. Moreover, the diurnal variation of O₃ concentrations displayed a typical single peak distribution pattern, with hourly O₃ concentration (ρ(O₃)) peaking at 15:00–16:00, suggesting that ρ(O₃) in Yichang was primarily influenced by local emissions. In addition, the sustained high ρ(O₃) on exceedance days were related to the local topography and ρ(O₃) along the river were strongly influenced by river-land breezes. The difference of meteorological factors between O₃ exceedance and non-exceedance days indicated that temperature and relative humidity had more pronounced impacts on ρ(O₃). Specifically, 89.6 % of ρ(O₃) exceedances occurred under meteorological conditions with temperature ≥25 °C and relative humidity between 25 % and 75 %, with wind speeds consistently below 5 m/s. It was recommended that environmental management departments should deploy related emission control measures in advance when the above meteorological conditions were forecasted, while fully considering the influence of the topography and river-land breeze on pollutant transports to optimize control strategies and coordinated prevention measures.

掌握局地臭氧污染特征及相关气象因子，对臭氧污染防治具有重要的科学支撑意义。以湖北省宜昌市2020 - 2022年O3浓度及相关气象资料为研究对象，探讨了宜昌市O3浓度的时空分布特征及相关气象因子的影响。结果表明：2020 - 2022年宜昌市O3污染呈现出明显的加重趋势和频次增加趋势；臭氧污染高发期为5 - 9月（以夏季为主），而前体NO2和TVOCs浓度较高出现在11 - 1月（以冬季为主），凸显了气象条件对臭氧形成的决定性作用。此外，O3浓度的日变化呈典型的单峰分布，每小时O3浓度（ρ(O3)）在15:00 ~ 16:00达到峰值，表明宜昌地区的ρ(O3)主要受局地排放的影响。此外，超限日ρ(O3)持续高值与局地地形有关，沿江ρ(O3)受河陆风影响较大。气象因子在O3超标日与非超标日之间的差异表明，温度和相对湿度对ρ(O3)的影响更为显著。其中，89.6%的ρ(O3)异常发生在温度≥25℃、相对湿度在25% ~ 75%之间、风速始终低于5 m/s的气象条件下。建议环境管理部门在预测到上述气象条件时，提前部署相关排放控制措施，同时充分考虑地形、河陆风对污染物运移的影响，优化控制策略，协调预防措施。

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引用次数: 0

Rapid determination of daily ionospheric F-layer critical frequency value using a quick-scale method based on Frequency-Time-Intensity plots 基于频率-时间-强度图的电离层f层日临界频率值快速测定方法

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-10-31 DOI: 10.1016/j.jastp.2025.106671

Varuliantor Dear , Jiyo Harjosuwito , Annis Siradj Mardiani , Adi Purwono , Afrizal Bahar , Indah Susanti , Satrio Adi Priyambada , Rezy Pradipta

The ionospheric F-layer critical frequency (foF2) is a fundamental parameter for space weather services. Conventionally, foF2 is manually scaled from ionograms using the URSI UAG-23 handbook, which, while accurate, is time-consuming and operator-dependent. This study proposes a simple Quick-Scale (QS) method to rapidly derive daily foF2 values from Frequency-Time Intensity (FTI) plots. The QS method converts FTI images to numeric data using Direct Linear Transformation (DLT) and interactive boundary tracing via a user-friendly Hypertext Markup Language (HTML) tool. The method was tested using Pameungpeuk ionosonde data for year 2020 and validated by four volunteers—two experts and two non-experts. Evaluation shows that the QS method requires approximately 3–4 min per day to extract daily foF2 values, compared to about 24 min needed for URSI UAG-23 manual scaling of 96 ionograms per day. Deviations reached ±2.5 MHz with RMSE and MBE patterns reflecting daily and seasonal ionospheric variations. Correlation coefficients exceeding 0.96 indicate strong agreement with standard foF2 data regardless of operator experience. However, minor time shifts due to image rendering and re-digitization processes were observed, suggesting potential systematic bias for high-precision applications. Overall, the QS method is feasible as a quick-look tool for operational space weather services and can be further refined with bias correction modules to enhance accuracy and temporal precision.

电离层f层临界频率（foF2）是空间气象服务的基本参数。通常，foF2是使用URSI UAG-23手册从电离图手动缩放的，虽然准确，但耗时且依赖于操作人员。本研究提出了一种简单的快速尺度（QS）方法，从频率-时间强度（FTI）图中快速获得每日foF2值。QS方法使用直接线性转换（DLT）将FTI图像转换为数字数据，并通过用户友好的超文本标记语言（HTML）工具进行交互式边界跟踪。该方法使用2020年的帕明堡离子探空仪数据进行了测试，并由四名志愿者（两名专家和两名非专家）进行了验证。评估表明，QS方法每天大约需要3-4分钟来提取每日的foF2值，相比之下，URSI UAG-23每天手动提取96离子图大约需要24分钟。反映电离层日和季节变化的RMSE和MBE模式偏差达到±2.5 MHz。相关系数超过0.96表明与标准foF2数据非常一致，无论操作员经验如何。然而，由于图像渲染和重新数字化过程，观察到较小的时间偏移，这表明高精度应用可能存在系统偏差。总体而言，QS方法作为业务空间天气服务的快速查看工具是可行的，并且可以通过偏差校正模块进一步完善，以提高精度和时间精度。

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引用次数: 0

Pre-seismic ionospheric disturbances (PIDs) associated With 2021 Mw 7.5 Northern Peru earthquake: GNSS and ground uplift observations 与2021 Mw 7.5秘鲁北部地震相关的震前电离层扰动（PIDs）： GNSS和地面隆起观测

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-09-27 DOI: 10.1016/j.jastp.2025.106644

Oluwasegun M. Adebayo , Esfhan A. Kherani , Alexandre A. Pimenta , Babatunde Rabiu

Predicting natural disasters such as earthquakes remains a major challenge in geosciences, with critical implications for early warning systems and disaster risk reduction. Among various precursory signals, ionospheric anomalies have gained increasing attention as potential indicators of impending seismic events. In this study, we examine pre-seismic ionospheric disturbances (PIDs) associated with the Mw 7.5 Northern Peru earthquake on November 28, 2021, using Global Navigation Satellite System (GNSS) Total Electron Content (TEC) and ground vertical velocity data. Significant sequential negative TEC anomalies were observed up to two hours prior to the mainshock, with multiple disturbances recorded by several GNSS receivers. The amplitudes of these disturbances increased as the earthquake approached, suggesting a progressive ionospheric response to the buildup of tectonic stress. Spectral analysis using the Short-Time Fourier Transform revealed center frequencies between 3.63 mHz and 4.80 mHz — within the acoustic/infrasonic range — indicating that such waves, possibly generated by foreshocks, may be responsible for these PIDs. To rule out other sources of TEC anomalies, we examined the TEC data for the previous day along the same trajectories and found no similar disturbances. Furthermore, geomagnetic conditions were quiet during the period, as indicated by Kp and Dst indexes two days before and after the earthquake. These findings contribute to the understanding of seismo-ionospheric coupling and highlight the potential role of ionospheric monitoring as a complementary approach to conventional seismic methods in earthquake early warning systems.

预测地震等自然灾害仍然是地球科学的一项重大挑战，对早期预警系统和减少灾害风险具有重要意义。在各种前兆信号中，电离层异常作为即将发生的地震事件的潜在指标而受到越来越多的关注。在这项研究中，我们使用全球导航卫星系统（GNSS）总电子含量（TEC）和地面垂直速度数据，研究了与2021年11月28日秘鲁北部7.5 Mw地震相关的震前电离层扰动（ids）。在主震发生前两小时，观测到明显的连续负TEC异常，几个GNSS接收器记录了多次干扰。这些扰动的振幅随着地震的临近而增加，这表明电离层对构造应力的积累有一个渐进的反应。使用短时傅立叶变换的频谱分析显示，中心频率在3.63 mHz和4.80 mHz之间，在声学/次声范围内，表明这种可能由前震产生的波可能是这些PIDs的原因。为了排除TEC异常的其他来源，我们沿着相同的轨迹检查了前一天的TEC数据，没有发现类似的干扰。从地震前后两天的Kp和Dst指数可以看出，这一时期的地磁条件是安静的。这些发现有助于理解地震-电离层耦合，并突出了电离层监测作为地震预警系统中常规地震方法的补充方法的潜在作用。

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引用次数: 0

Enhanced estimation of seasonal irradiance patterns: The adapted time synchronous average method 季节辐照度模式的增强估计：适应时间同步平均法

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-09-16 DOI: 10.1016/j.jastp.2025.106620

Mohammed Telidjane , Benaoumeur Bakhti

Accurately separating the cyclic pattern from background noise in irradiance data is critical for various applications, including monitoring photovoltaic panels. However, seasonality, evident as amplitude modulation in the irradiance waveform, poses a significant challenge to existing methods like Time Synchronous Averaging (TSA) and Cepstral Editing (CE). These methods struggle to effectively remove the influence of seasonality on the estimated cyclic pattern. This work proposes a novel method called the Adapted Time Synchronous Average (ATSA) to address these limitations. The new approach is inspired by the application of cyclostationary tools used in mechanical signals of rotating machinery. ATSA employs a three-step approach: signal normalization to mitigate seasonality, TSA estimation using the normalized data, and adaptive filtering for signal reconstruction. Our analysis demonstrates that ATSA outperforms TSA and CE in separating the cyclic pattern from the stochastic noise component in irradiance data.

在辐照度数据中准确地从背景噪声中分离循环模式对于各种应用至关重要，包括监测光伏板。然而，季节性，如辐照度波形中的幅度调制，对时间同步平均（TSA）和倒谱编辑（CE）等现有方法提出了重大挑战。这些方法难以有效地消除季节性对估计周期型的影响。这项工作提出了一种称为自适应时间同步平均（ATSA）的新方法来解决这些限制。新方法的灵感来自于在旋转机械的机械信号中使用的循环静止工具的应用。ATSA采用三步方法：信号归一化以减轻季节性，使用归一化数据进行TSA估计，以及自适应滤波进行信号重建。我们的分析表明，在从辐照数据中的随机噪声成分中分离循环模式方面，ATSA优于TSA和CE。

引用次数: 0

Supervised land cover classification of the Indian Sundarbans mangrove forest using random forest and Landsat imagery 利用随机森林和Landsat图像对印度孙德尔本斯红树林进行监督土地覆盖分类

IF 1.9 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics

Pub Date : 2025-12-01 Epub Date: 2025-10-17 DOI: 10.1016/j.jastp.2025.106663

M. Kasiselvanathan, P. Sridevi

Rapid population enhancement and economic development have significantly changed land use and land cover (LULC) in ecologically sensitive Sundarbans, the world's most fragile ecosystem. Accurate classification of LULC is important for environmental monitoring, resource management, and policy-making. In the present paper, the authors have employed a machine learning (ML) technique, Random Forest (RF), to classify land cover changes in the Sundarbans over two time periods: 2003, and 2023. Landsat-7 and Landsat-8 satellite imagery have been used for land cover (LC) analysis, followed by data pre-processing techniques including layer stacking, mosaicking, and spectral signature collection. Around 640 and 840 training samples have been used for classification, for the year 2003 and 2023 respectively with 30 % samples used for validation. The RF model utilized 500 trees (n-tree) and four variables at each split (m-try). The accuracy has been assessed with confusion matrices, and Kappa statistics showing an accuracy of 0.84 and 0.85 for the year 2003 and 2023 respectively. The result reveals an increase in sparse forest, open land, and sand bar, and decline in water bodies and dense forest. The reason may be due to anthropogenic activities and climate-induced factors such as rising sea levels and storm surges. The findings indicate Sundarbans ecosystem's susceptibility and the necessity of sustainable management techniques. This study indicates that future research should focus on longer time-series analysis, improved scalability, and cloud platform integration to improve. The research demonstrates that ML-based land cover classification can be a useful monitoring tool with high accuracy for environmental conservation.

孙德尔本斯是世界上最脆弱的生态系统，其土地利用和土地覆盖发生了显著变化。土地利用价值的准确分类对环境监测、资源管理和政策制定具有重要意义。在本文中，作者采用了一种机器学习（ML）技术——随机森林（RF），对孙德尔本斯地区2003年和2023年两个时间段的土地覆盖变化进行了分类。Landsat-7和Landsat-8卫星图像用于土地覆盖（LC）分析，然后进行数据预处理技术，包括层堆叠、马赛克和光谱特征收集。2003年和2023年分别使用了大约640和840个训练样本进行分类，其中30%的样本用于验证。RF模型利用500棵树（n-tree）和4个变量在每次分割（m-try）。准确度用混淆矩阵进行了评估，Kappa统计显示2003年和2023年的准确度分别为0.84和0.85。结果表明：疏林、开阔地和沙坝增加，水体和茂密林减少；原因可能是人为活动和气候引起的因素，如海平面上升和风暴潮。研究结果表明孙德尔本斯生态系统的易感性和可持续管理技术的必要性。本研究表明，未来的研究应侧重于更长的时间序列分析、改进的可扩展性和云平台集成来改进。研究表明，基于机器学习的土地覆被分类可以作为一种有用的、高精度的环境保护监测工具。

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