Two-dimensional Modeling of the Tearing-mode-governed Magnetic Reconnection in the Large-scale Current Sheet above the Two-ribbon Flare

We attempt to model magnetic reconnection during the two-ribbon flare in a gravitationally stratified solar atmosphere with the Lundquist number of S=10~6 using 2 D simulations.We found that the tearing mode instability leads to inhomogeneous turbulence inside the reconnecting current sheet(CS)and invokes the fast phase of reconnection.Fast reconnection brings an extra dissipation of magnetic field which enhances the reconnection rate in an apparent way.The energy spectrum in the CS shows a power law pattern and the dynamics of plasmoids govern the associated spectral index.We noticed that the energy dissipation occurs at a scale l_(ko)of 100-200 km,and the associated CS thickness ranges from 1500 to 2500 km,which follows the Taylor scale l_(T)=l_(ko)S_(1/6).The termination shock(TS)appears in the turbulent region above flare loops,which is an important contributor to heating flare loops.Substantial magnetic energy is converted into both kinetic and thermal energies via TS,and the cumulative heating rate is greater than the rate of the kinetic energy transfer.In addition,the turbulence is somehow amplified by TS,in which the amplitude is related to the local geometry of the TS.

A Statistical Study of Magnetic Flux Emergence in Solar Active Regions Prior to Strongest Flares

Using the data on magnetic field maps and continuum intensity for Solar Cycles 23 and 24,we explored 100 active regions(ARs)that produced M5.0 or stronger flares.We focus on the presence/absence of the emergence of magnetic flux in these ARs 2-3 days before the strong flare onset.We found that 29 ARs in the sample emerged monotonically amidst quiet-Sun.A major emergence of a new magnetic flux within a pre-existing AR yielding the formation of a complex flare-productive configuration was observed in another 24 cases.For 30 ARs,an insignificant(in terms of the total magnetic flux of pre-existing AR)emergence of a new magnetic flux within the pre-existing magnetic configuration was observed;for some of them the emergence resulted in a formation of a configuration with a small δ-sunspot;11 out of 100 ARs exhibited no signatures of magnetic flux emergence during the entire interval of observation.In six cases the emergence was in progress when the AR appeared on the Eastern limb,so that the classification and timing of emergence were not possible.We conclude that the recent flux emergence is not a necessary and/or sufficient condition for strong flaring of an AR.The flux emergence rate of flare-productive ARs analyzed here was compared with that of flare-quiet ARs analyzed in our previous studies.We revealed that the flare-productive ARs tend to display faster emergence than the flare-quiet ones do.

The Evolution of Photospheric Current Density During an X9.3-Class Solar Flare

This paper deduced the temporal evolution of the magnetic field through a series of high-resolution vector magnetograms and calculated the fine distribution map of current density during an X9.3-class flare eruptions using Ampère's law.The results show that a pair of conjugate current ribbons exist on both sides of the magnetic neutral line in this active region,and these conjugate current ribbons persist before,during,and after the flare.It was observed that the X9.3-class flare brightened in the form of a bright core and evolved into a double-ribbon flare over time.Importantly,the position of the double-ribbon flare matches the position of the current ribbons with high accuracy,and their morphologies are very similar.By investigating the complexity of current density and flare morphology,we discovered a potential connection between the eruption of major flares and the characteristics of current density.

The Dependence between Solar Flare Emergence and the Average Background Solar X-Ray Flux Emission

Solar flares, sudden bursts of intense electromagnetic radiation from the Sun, can significantly disrupt technological infrastructure, including communication and navigation satellites. To mitigate these risks, accurate forecasting of solar activity is crucial. This study investigates the potential of the Sun’s background X-ray flux as a tool for predicting solar flares. We analyzed data collected by solar telescopes and satellites between the years 2013 and 2023, focusing on the duration, frequency, and intensity of solar flares. We compared these characteristics with the background X-ray flux at the time of each flare event. Our analysis employed statistical methods to identify potential correlations between these solar phenomena. The key finding of this study reveals a significant positive correlation between solar flare activity and the Sun’s background X-ray flux. This suggests that these phenomena are interconnected within the framework of overall solar activity. We observed a clear trend: periods with increased occurrences of solar flares coincided with elevated background flux levels. This finding has the potential to improve solar activity forecasting. By monitoring background flux variations, we may be able to develop a more effective early warning system for potentially disruptive solar flares. This research contributes to a deeper understanding of the complex relationship between solar flares and the Sun’s overall radiative output. These findings indicate that lower-resolution X-ray sensors can be a valuable tool for identifying periods of increased solar activity by allowing us to monitor background flux variations. A more affordable approach to solar activity monitoring is advised.

A Confined Two-peaked Solar Flare Observed by EAST and SDO

The solar flare is one of the most violent explosions,and can disturb the near-Earth space weather.Except for commonly single-peaked solar flares in soft X-ray,some special flares show intriguing a two-peak feature that is deserved much more attentions.Here,we reported a confined two-peaked solar flare and analyzed the associated eruptions using high-quality observations from Educational Adaptive-optics Solar Telescope and Solar Dynamics Observatory.Before the flare,a magnetic flux rope(MFR)formed through partially tether-cutting reconnection between two sheared arches.The flare occurred after the MFR eruption that was confined by the overlying strong field.Interestingly,a small underlying filament immediately erupted,which was possibly destabilized by the flare ribbon.The successive eruptions were confirmed by the analysis of the emission measure and the reconnection fluxes.Therefore,we suggest that the two peaks of the confined solar flare are corresponding to two episodes of magnetic reconnection during the successive eruptions of the MFR and the underlying filament.

Statistical Study of the Geoeffectivity of Halo Coronal Mass Ejections Associated with X-Class Flares during Solar Cycles 23 and 24

By analysing a long series of data (1996-2019), we show that solar cycle 23 was more marked by violent solar flares and coronal mass ejections (CMEs) compared to solar cycle 24. In particular, the halo coronal mass ejections associated with X-class flares appear to be among the most energetic events in solar activity given the size of the flares, the speed of the CMEs and the intense geomagnetic storms they produce. Out of eighty-six (86) X-class halo CMEs, thirty-seven (37) or 43% are highly geoeffective;twenty-four (24) or approximately 28% are moderately geoeffective and twenty-five (25) or 29% are not geoeffective. Over the two solar cycles (1996 to 2019), 71% of storms were geoeffective and 29% were not. For solar cycle 23, about 78% of storms were geoeffective, while for solar cycle 24, about 56% were geoeffective. For the statistical study based on speed, 85 halo CMEs associated with X-class flares were selected because the CME of 6 December 2006 has no recorded speed value. For both solar cycles, 75.29% of the halo CMEs associated with X-class flares have a speed greater than 1000 km/s. The study showed that 42.18% of halo (X) CMEs with speeds above 1000 km/s could cause intense geomagnetic disturbances. These results show the contribution (in terms of speed) of each class of halo (X) CMEs to the perturbation of the Earth’s magnetic field. Coronal mass ejections then become one of the key indicators of solar activity, especially as they affect the Earth.

Synthetic analysis of a two-ribbon microflare

High-resolution Stokes spectral data of Hα, Ca Ⅱ 8542A, and Fe 16302.5A lines for a two-ribbon microflare （TRMF） were simultaneously obtained by the THEMIS telescope on 2002 September 5. We derive the intensity, velocity, and longitudinal magnetic field maps. The hard X-ray emission observed by RHESSI provides evidence of nonthermal particle acceleration in the TRMF. Using Ha and Ca Ⅱ 8542A line profiles and a non-LTE calculation, we obtain semi-empirical atmospheric models for the two brightest kernels of the TRME Our result indicates that the temperature enhancement in the chromosphere is more than 2500 K. The kinetic and radiative energies at the kernels are also estimated, resulting in an estimate of the total energy of the TRMF of about 2.4×10^29 erg. Observations indicate that the TRMF results from the low coronal magnetic reconnection following the eruption of a small fila- ment. However, the local temperature ＂bump＂ in the chromosphere presents a puzzle for such a standard flare model. A possible solution to this is discussed.

New Cases of Superflares on Slowly Rotating Solar-type Stars and Large Amplitude Superflares in G-and M-type Main Sequence Stars

In our previous work,we searched for superflares on different types of stars while focusing on G-type dwarfs using entire Kepler data to study statistical properties of the occurrence rate of superflares.Using these new data,as a byproduct,we found 14 cases of superflare detection on 13 slowly rotating Sun-like stars with rotation periods of24.5–44 days.This result supports the earlier conclusion by others that the Sun may possibly undergo a surprise superflare.Moreover,we found 12 and seven new cases of detection of exceptionally large amplitude superflares on six and four main sequence stars of G-and M-type,respectively.No large-amplitude flares were detected in A,F or K main sequence stars.Here we present preliminary analysis of these cases.The superflare detection,i.e.,an estimation of flare energy,is based on a more accurate method compared to previous studies.We fit an exponential decay function to flare light curves and study the relation between e-folding decay time,τ,versus flare amplitude and flare energy.We find that for slowly rotating Sun-like stars,large values ofτcorrespond to small flare energies and small values ofτcorrespond to high flare energies considered.Similarly,τis large for small flare amplitudes andτis small for large amplitudes considered.However,there is no clear relation between these parameters for large amplitude superflares in the main sequence G-and M-type stars,as we could not establish clear functional dependence between the parameters via standard fitting algorithms.

LyαEmission Enhancement Associated with Soft X-Ray Microflares

Lyα(Lyα,1216 A)is the strongest emission line in the solar ultraviolet spectrum.In the present work,we obtained a Lyαenhancement catalog covering flares larger than B1 class from the GOES/EUVS data during 2010-2016.We focused on the 242 B-class events which are less investigated,however,show non-negligible Lyαemission enhancement.We found that on average the Lyαpeak of B-class flares is 0.85%stronger than the background.For the flare energetics,it is found that the weaker the soft X-ray(SXR)flare,the larger the ratio of the radiated energy in Lyαto SXR.Using the RHESSI data and multi-wavelength observations taken by SDO-AIA,we diagnose the thermal and non-thermal properties of several flares.Three case studies show that the coincidence of the Lyαpeak with the SXR time-derivative peak is not a sufficient condition of the nonthermal property of a Lyαmicroflare.The Lyαenhancement in the microflares may be caused by the nonthermal electron beams or/and thermal conduction.However for typeⅢevents,we found that the delay of the Lyαpeak with respect to the SXR peak can be attributed to either the Lyαemission from a filament erupted or the cooling of the thermal plasma in flare loops.Furthermore,interestingly the Lyαemission from filaments can not only occur in the decay phase of the flare,but also in the preflare phase.In this case,the Lyαemission was originated from an erupted filament which probably initiated the flare.

Research Progress on Solar Flare Forecast Methods Based on Data-driven Models

Eruption of solar flares is a complex nonlinear process,and the rays and high-energy particles generated by such an eruption are detrimental to the reliability of space-based or ground-based systems.So far,there are not reliable physical models to accurately account for the flare outburst mechanism,but a lot of data-driven models have been built to study a solar flare and forecast it.In the paper,the status of solar-flare forecasting is reviewed,with emphasis on the machine learning methods and data-processing techniques used in the models.At first,the essential forecast factors strongly relevant to solar flare outbursts,such as classification information of the sunspots and evolution pattern of the magnetic field,are reviewed and analyzed.Subsequently,methods of resampling for data preprocessing are introduced to solve the problems of class imbalance in the solar flare samples.Afterwards,typical model structures adopted for flare forecasting are reviewed from the aspects of the single and fusion models,and the forecast performances of the different models are analyzed.Finally,we herein summarize the current research on solar flare forecasting and outline its development trends.

Flare Forecast Model Based on DS-SMOTE and SVM with Optimized Regular Term

The research of flare forecast based on the machine learning algorithm is an important content of space science.In order to improve the reliability of the data-driven model and weaken the impact of imbalanced data set on its forecast performance,we proposes a resampling method suitable for flare forecasting and a Particle Swarm Optimization(PSO)-based Support Vector Machine(SVM)regular term optimization method.Considering the problem of intra-class imbalance and inter-class imbalance in flare samples,we adopt the density clustering method combined with the Synthetic Minority Over-sampling Technique(SMOTE)oversampling method,and performs the interpolation operation based on Euclidean distance on the basis of analyzing the clustering space in the minority class.At the same time,for the problem that the objective function used for strong classification in SVM cannot adapt to the sample noise,In this research,on the basis of adding regularization parameters,the PSO algorithm is used to optimize the hyperparameters,which can maximize the performance of the classifier.Finally,through a comprehensive comparison test,it is proved that the method designed can be well applied to the flare forecast problem,and the effectiveness of the method is proved.

日地L5太阳探测工程概述

南京大学联合中国气象局、上海航天技术研究院等单位共同建议的日地L5太阳探测工程——“羲和二号”,将在国际上首次发射一颗人造探测器至日地系统第5个拉格朗日点,通过精测矢量磁场、揭示三维爆发和精准预警预报,解答“活动区磁场的产生演化及其与太阳爆发的物理联系”和“太阳爆发的传播规律及其与灾害性空间天气的关系”这2个太阳物理和空间天气领域亟待解决的重大科学和应用问题。本文重点阐述“羲和二号”的科学与应用目标,简要介绍其科学载荷和初步方案。联合日地连线方向上的太阳探测,“羲和二号”的实施将开启我国太阳立体探测时代,拓展人类对太阳爆发机制的理解,为空间天气预警预报带来革命性突破。

基于FLARESIM模拟的LNG接收站高架火炬设计选型研究

火炬系统是维护LNG接收站安全运行的重要设备。为了直观有效的掌握高架火炬热辐射对接收站内设施及周边环境的影响,评估火炬设置的合理性与安全性。在相关规范内容的基础上细化LNG接收站火炬系统处理能力的选型工况,其作为重要的输入条件,提高火炬设计规模及火炬系统设计的准确性,在此基础上进一步通过FLARESIM软件对高架火炬包括筒体尺寸、火炬头及火炬高度等进行模拟计算,在标准允许范围内有效识别并评估热辐射对接受点的影响,以确定高架火炬的设计参数及布置位置。一般说来,常规LNG接收站火炬泄放量最大组合工况为储罐漏热+大气压降低+控制阀失效或储罐漏热+大气压降低+卸船充装时的置换和闪蒸,并通过调整火炬位置及火炬筒高度可以满足热辐射的要求及气体扩散浓度要求。

基于偏振特征区域分解的耀光抑制方法

海面探测领域中,太阳耀光导致光电探测设备大面积像元饱和,严重妨碍了海面目标的信息采集工作。为了对太阳耀光进行抑制,提出基于偏振特征区域分解的耀光抑制方法。该方法通过分析探测器对偏振数据的采集情况,将耀光区域进行特征分解。对偏振非饱和耀光区域,通过完全偏振分解方法解算去偏振分量图像,滤除部分反射光,恢复耀光遮蔽区域场景信息。同时设置灰度容限,剥离偏振饱和耀光区域。针对偏振饱和耀光区域采集数据失真的问题,采用FMM图像修复算法,将非耀光区域水面信息扩散到耀光区域,重建灰度数据。本文在室内搭建耀光模拟及偏振成像平台,对采集图像进行算法测试。实验结果表明:抑制后的图像,饱和像素数平均降低了99.98%,基本消除了饱和像素。同时灰度均值降低了59.35%,并显著提高了信噪比。验证了本文方法对耀光杂波抑制的有效性与可行性。

无人井口平台等离子火炬的研究和应用

南海某油田后期伴生气量比较少,且热值比较低,不易燃烧。对此,文章应用了一种新型等离子火炬系统,满足平台伴生气稳定燃烧要求。

太阳耀斑对东海海域船舶AIS通信的影响分析

太阳耀斑是一种强烈的电磁辐射爆发,耀斑爆发时会影响地球磁场的稳定,造成电离层扰动,干扰无线电通信,并对航天器、卫星导航系统等造成影响。研究了太阳耀斑对船舶AIS通信影响,以中国东海海域为例,分析2024年5月初数次耀斑发生的前、中、后时间段的AIS数据。研究发现,船舶AIS数据本身传输的错误占比与太阳耀斑没有明显关系,但是根据AIS数据的船舶定位信息和时间计算得到的表观速度的方差在耀斑发生的前、中、后时间段有明显差异,结果表明太阳耀斑对船舶AIS的定位信息有较大影响。

高架火炬掺氢燃烧热辐射模拟研究

目的天然气掺氢后燃烧特性会发生改变,因此,有必要对掺氢天然气热放空过程进行研究,以确定掺氢输送条件下原有高架火炬适用的工况条件,从而确保天然气管输系统在掺氢输送时的安全。方法结合掺氢燃烧实验和CFD数值模拟,研究掺氢(摩尔分数0~20%)天然气进行扩散燃烧时燃烧特性及热辐射半径变化情况,揭示掺氢对燃烧热辐射半径的影响机理,明确API STD 521—2014《泄压和减压系统》中热辐射半径解析模型可用于掺氢天然气的计算。结果在等体积流量下,掺氢减小了热释放量从而减短了火焰长度,而在侧风作用下的火焰倾斜角几乎不变,因此缩小了热辐射半径;在等质量流量下,掺氢增加了热释放量从而增长了火焰长度,而火焰倾斜角变大,使得热辐射半径变化极小。同时,风速增大会导致热辐射半径扩大。结论在安全热辐射半径不变的前提下,按体积流量计算,掺氢条件下最多可提高19%~23%体积流量的放空量,火炬系统的排放效率有所提高;按质量流量计算,掺氢条件下高架火炬的质量流量放空量与掺氢前相比几乎保持不变。

醋酸阿比特龙治疗去势抵抗性前列腺癌早期出现PSA Flare现象的初步分析

目的分析我院泌尿外科治疗中心确诊为去势抵抗型前列腺癌(CRPC)患者、应用醋酸阿比特龙联合泼尼松治疗早期出现PSA Flare现象后对其前列腺特异抗原(PSA)缓解率的影响及部分基线值对PSA Flare出现概率的影响,为后续治疗提供经验。方法本研究共纳入2015年10月至2017年10月接受醋酸阿比特龙联合泼尼松治疗的CRPC患者共计86例,分析其中用药12周以上的55例有效病例的PSA基线值及其变化。结果 55例患者PSA总体缓解为56.4%,其中27.2%(15/55例)的患者出现了PSA Flare现象;PSA再次下降至基线值水平以下的中位时间为3.1(2~6)月。CRPC患者的年龄、PSA基线值、Gleason评分和患者出现PSA Flare现象无明确关联。结论对于醋酸阿比特龙联合泼尼松治疗CRPC患者来说,PSA Flare现象的发生比较常见,和患者年龄、PSA基线值、Gleason评分并无明确关联。在治疗早期药物暴露时间要足够,部分患者可能≥12周,个别患者PSA Flare持续时间达到24周,因此出现PSA Flare并不能说明疾病进展,对疾病进展的预估要结合影像学等多方面证据。

犀角地黄汤联合来氟米特对系统性红斑狼疮的改善作用

目的观察犀角地黄汤联合来氟米特对系统性红斑狼疮(systemic lupus erythema,SLE)的改善及对Th1/Th2失衡的影响。方法选取123例急性活动期热毒炽盛证SLE患者,用随机数字表法分为对照组(n=61)和试验组(n=62)。对照组采用醋酸泼尼松片联合来氟米特治疗,试验组在对照组治疗的基础上用犀角地黄汤治疗。比较治疗前、治疗后1个月和治疗后3个月2组疾病活动度评分、中医证候评分、补体C3水平和Th1/Th2值;比较2组抗ds-DNA抗体阳性率、临床疗效和不良反应。结果治疗前2组SLE疾病活动度评分(SLE disease activity score,SLEDAI)、中医证候评分、补体C3水平和Th1/Th2值比较,差异无统计学意义;治疗后1、3个月试验组SLEDAI评分、中医证候评分、Th1/Th2值和抗ds-DNA抗体阳性率均明显低于对照组,补体C3水平和临床总有效率均明显高于对照组(P<0.05);试验组不良反应发生率明显低于对照组(P<0.05)。结论犀角地黄汤可改善急性活动期热毒炽盛证SLE患者疾病活动度及中医证候、实验室指标,提升临床疗效,减少糖皮质激素及免疫抑制剂所致的不良反应。

日冕准周期快模磁声波的研究进展

日冕准周期快模磁声波是日冕中较常见的一种波动现象,这种波动现象通常与耀斑和日冕物质抛射等太阳活动爆发相关。根据准周期快模磁声波列的特征,还可以细分为窄准周期快模磁声波和宽准周期快模磁声波。研究表明,准周期快模磁声波包含的关键物理信息可以用来诊断耀斑核心区域特征、测量日冕磁场以及探测能量释放和传输等。简单叙述了准周期快模磁声波相关的主要观测特征和模拟结果,重点介绍准周期快模磁声波的最新研究进展及冕震学应用,讨论了准周期快模磁声波的激发机制,展望了未来需要研究的问题,并提供相关研究方法作为参考。