Solar Physics最新文献

{"title":"A New Solar Hard X-ray Image Reconstruction Algorithm for ASO-S/HXI Based on Deep Learning","authors":"Yuehan Xia,&nbsp;Yang Su,&nbsp;Hui Liu,&nbsp;Wenhui Yu,&nbsp;Zhentong Li,&nbsp;Wei Chen,&nbsp;Yu Huang,&nbsp;Weiqun Gan","doi":"10.1007/s11207-024-02399-4","DOIUrl":"10.1007/s11207-024-02399-4","url":null,"abstract":"<div><p>Most solar hard X-ray (HXR) imagers in the past and current solar missions obtain X-ray images via Fourier transform imaging technology, which requires proper imaging algorithms to reconstruct images from spatially-modulated or temporally-modulated signals. A variety of algorithms have been developed during the last 50 years for the characteristics of respective instruments. In this work, we present a new imaging algorithm developed based on deep learning for the Hard X-ray Imager (HXI) onboard the Advanced Space-based Solar Observatory (ASO-S) and the preliminary test results of the algorithm with both simulated data and observations. We first created a training dataset by obtaining modulation data from simulated HXR images of single, double and loop-shaped sources, respectively, and the patterns of HXI sub-collimators. Then, we introduced machine-learning algorithm to develop a pattern-based deep learning network model: HXI_DLA, which can directly produce an image from modulation counts. After training the model with simple sources, we tested DLA for simple sources, extended sources, and double sources for imaging dynamic range. Finally, we compared CLEAN and DLA images reconstructed from HXI observations of three flares. Overall, these imaging tests revealed that the current HXI_DLA method produces comparable image result to those from the widely used imaging method CLEAN. In some cases, DLA images are even slightly better. Besides, HXI_DLA is super fast for imaging and parameter-free. Although this is only the first step towards a fully developed and practical DLA method, the tests have shown the potential of deep learning in the field of solar hard X-ray imaging.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142645684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of Sunspot Areas Derived by Automated Sunspot-Detection Methods","authors":"Yoichiro Hanaoka","doi":"10.1007/s11207-024-02402-y","DOIUrl":"10.1007/s11207-024-02402-y","url":null,"abstract":"<div><p>Sunspot-area measurements using digital images captured by two telescopes at the Mitaka campus of the National Astronomical Observatory of Japan are conducted using automated sunspot detection. A comparison between sunspot areas derived from Mitaka and those from the reference data by Mandal et al. (<i>Astron. Astrophys.</i> <b>640,</b> A78, 2020), who compiled a crosscalibrated daily sunspot-area catalog, revealed that the correlation coefficients between them are high (0.96 – 0.97), whereas the areas in the Mitaka data are 70 – 83% of those of Mandal et al. The correlation is limited by the differences in observation times and detection capabilities of spots near the limb, with discrepancies in areas arising from different definitions of spot outlines. Given the high correlation and the ease of calibrating area discrepancies with a correction factor, automated sunspot detection appears promising for future sunspot-area measurements. Furthermore, we addressed the measurements of brightness deficit caused by sunspots.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calibration and Performance of the Full-Disk Vector MagnetoGraph (FMG) on Board the Advanced Space-Based Solar Observatory (ASO-S)","authors":"Xianyong Bai,&nbsp;Yuanyong Deng,&nbsp;Haiying Zhang,&nbsp;Jianfeng Yang,&nbsp;Fu Li,&nbsp;Jiangtao Su,&nbsp;Suo Liu,&nbsp;Yongliang Song,&nbsp;Kaifan Ji,&nbsp;Yu Huang,&nbsp;Xiao Yang,&nbsp;Dongguang Wang,&nbsp;Jiaben Lin,&nbsp;Junfeng Hou,&nbsp;Yingzi Sun,&nbsp;Wei Duan,&nbsp;Qian Song,&nbsp;Yang Bai,&nbsp;Xiaofan Wang,&nbsp;Haiqing Xu,&nbsp;Jie Chen,&nbsp;Ziyao Hu,&nbsp;Zhaoying Zheng,&nbsp;Houkun Ni,&nbsp;Yizhong Zeng,&nbsp;Zhen Wu,&nbsp;Jianing Wang,&nbsp;Wei Ge,&nbsp;Juan Lv,&nbsp;Lun Shen,&nbsp;Nange Wang,&nbsp;Jiawei He,&nbsp;Chenjie Wang","doi":"10.1007/s11207-024-02400-0","DOIUrl":"10.1007/s11207-024-02400-0","url":null,"abstract":"<div><p>We present the ground calibration and on-orbit performance of the Full-disk vector MagnetoGraph (FMG) payload on board the Advanced Space-Based Solar Observatory (ASO-S), which is China’s first spaceborne magnetograph. FMG has the ability to acquire the full-disk Stokes I, Q/I, U/I, and V/I maps with a spatial resolution of about 1.5 arcsec. The Lyot filter for the flight model has a full width at half maximum of 0.01 nm. Using two calibration lenses, we measure the non-uniform wavelength drift across the entire field of view, with a maximum value of 0.003 nm. The on-orbit polarization sensitivity is approximately 0.00039 and 0.0009 for the deep integration and routine modes, corresponding to a cadence of 18 and 2 minutes, respectively. The corresponding sensitivity of the longitudinal magnetic field is 8.5 G and 20 G with the current linear calibration coefficient of 21,913. Since 1 April 2023, FMG has released Level 2 filtergram and longitudinal magnetic field data products for active regions. Furthermore, line-of-sight Carrington synoptic magnetograms spanning a 27-day solar rotation can be generated, which have been released to the public since February 2024. The longitudinal magnetic field obtained by FMG is consistent with that of the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory and the Solar Magnetism and Activity Telescope at Huairou Solar Observing Station for the regions without magnetic saturation.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Helioseismic Constraints: Past, Current, and Future Observations","authors":"Thierry Appourchaux","doi":"10.1007/s11207-024-02403-x","DOIUrl":"10.1007/s11207-024-02403-x","url":null,"abstract":"<div><p>I will review the history of the helioseismic observations since the beginning of the field. I will explain how each instrument was designed based upon the required observables, and to which modes these instruments are sensitive. The impact of these sensitivities on the rotation and structure inversion will be developed. I will conclude with what remains to be done in this field for the future of detection.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Precursory Signs of Large Forbush Decreases: The Criterion of Anisotropy","authors":"M. Papailiou,&nbsp;M. Abunina,&nbsp;H. Mavromichalaki,&nbsp;N. Shlyk,&nbsp;S. Belov,&nbsp;A. Abunin,&nbsp;M. Gerontidou,&nbsp;A. Belov,&nbsp;V. Yanke","doi":"10.1007/s11207-024-02391-y","DOIUrl":"10.1007/s11207-024-02391-y","url":null,"abstract":"<div><p>The study of precursors preceding Forbush decreases belongs to the applied side of space research and to a relatively new area of modern science, that of Space Weather. Moreover, it is a pioneering and innovative research field with interesting results. In the framework of the above, the Athens Cosmic Ray Group of the National and Kapodistrian University of Athens (NKUA) and the Cosmic Ray Group of the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation of the Russian Academy of Sciences (IZMIRAN) have collaborated in investigating predecreases and/or preincreases of the cosmic-ray intensity before the development of a Forbush decrease, that could serve as precursory signs of the upcoming event and consequently play a significant role in the prediction of cosmic-ray and geomagnetic activity. In this work, the criterion of the increased anisotropy one hour before the onset of the event (<span>(A_{mathit{xyb}})</span>, %) is being examined for large Forbush decreases. Specifically, Forbush decreases with magnitude greater than 5%, accompanied with geomagnetic storms (i.e., geomagnetic index Dst &lt; −100 nT and 5 ≤ Kp-index ≤ 9) and characterized by <span>(A_{mathit{xyb}} geq )</span> 0.8% were analyzed. The catalog of Forbush Effects and Interplanetary Disturbances of IZMIRAN was used for analyzing the solar, interplanetary, and geomagnetic conditions during each event. Additionally, for a visual inspection of the precursory signs in each event the Ring of Stations method (i.e., asymptotic longitude–time diagram) was applied. Results revealed that the increased anisotropy one hour before the main phase of the Forbush decrease is a valid and reliable criterion of precursors that can be eventually used in the development of a Forbush decrease prognosis application tool.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 11","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142600673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Tests and Calibrations of the Hard X-ray Imager Aboard ASO-S","authors":"Yang Su,&nbsp;Zhe Zhang,&nbsp;Wei Chen,&nbsp;Dengyi Chen,&nbsp;Fu Yu,&nbsp;Yiming Hu,&nbsp;Yan Zhang,&nbsp;Fanxiaoyu Xia,&nbsp;Changxue Chen,&nbsp;Zhentong Li,&nbsp;Xiankai Jiang,&nbsp;Yu Huang,&nbsp;Yongqiang Zhang,&nbsp;Wei Liu,&nbsp;Tao Ma,&nbsp;Dong Li,&nbsp;Wenhui Yu,&nbsp;Youping Li,&nbsp;Mingsheng Cai,&nbsp;Jianhua Guo,&nbsp;Yongyi Huang,&nbsp;Haoxiang Wang,&nbsp;Yaoming Liang,&nbsp;Miao Ma,&nbsp;Jianping Wang,&nbsp;Shanshan Zhu,&nbsp;Jinyou Tao,&nbsp;Jirui Yu,&nbsp;Jianfeng Yang,&nbsp;Jian Wu,&nbsp;Weiqun Gan","doi":"10.1007/s11207-024-02392-x","DOIUrl":"10.1007/s11207-024-02392-x","url":null,"abstract":"<div><p>The Hard X-ray Imager (HXI) aboard the Advanced Space-based Solar Observatory (ASO-S) is an instrument designed to observe hard X-ray (HXR) spectra and images of solar flares. Having 91 subcollimators to modulate incident X-rays, HXI can obtain 91 modulation data and 45 visibilities to reconstruct images with a spatial resolution as high as <span>(sim 3.1)</span> arcsec. HXI was launched on 9 October 2022 and powered up on 17 October 2022. After the on-orbit testing phase lasting for three months, HXI was ready for regular observations on 18 January 2023. With fine-tuning of the detectors and electronics, we were able to expand the energy range from <span>(sim 30)</span> – 200 keV to <span>(sim 10)</span> keV – 300 keV, which significantly raised the scientific values of the data and the number of detected flare events. This paper presents the changes and improvements of HXI instrument since 2019, the important ground tests, on-orbit tests, and calibration works. We also present the light curves, spectra, and reconstructed images of one flare observed by HXI on 6 January 2023.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-024-02392-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142555191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving the Spectral Resolution and Wavelength Scale of SDO/EVE MEGS-A Flare Observations","authors":"Gabriela Gonzalez,&nbsp;Phillip Chamberlin,&nbsp;Vicki Herde","doi":"10.1007/s11207-024-02394-9","DOIUrl":"10.1007/s11207-024-02394-9","url":null,"abstract":"<div><p>The Extreme ultraviolet Variability Experiment (EVE) is one of three instruments onboard the Solar Dynamics Observatory (SDO). This paper focuses on using the “A” channel on the Multiple EUV Grating Spectrographs (MEGS-A) on EVE, which measures wavelengths of 5 – 37 nm, to improve the wavelength scale accuracy and spectral resolution during solar flares. EVE’s least processed (Level 0B) data product is used to create updated wavelength scales that are shown, through this analysis, to make more precise spectral measurements compared to EVE Level 2 data. An X2.2 class flare that occurred on 15 February 2011, SOL2011-02-15T0156, was used to derive the pixel-to-wavelength scales. An improvement range of 5.21% to 11.35% was found in the emission line widths. In the future, these measurements can be used for improved Doppler velocity calculations of the accelerated plasma of various temperatures during solar flares.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-024-02394-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142524434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Solar FUV-UV Spectra Measurement Experiment in the Near Space by High Altitude Balloon","authors":"Fei Wei,&nbsp;Xuanyi Zhang","doi":"10.1007/s11207-024-02396-7","DOIUrl":"10.1007/s11207-024-02396-7","url":null,"abstract":"<div><p>An experiment measuring the solar far-ultraviolet-ultraviolet (FUV-UV) irradiance with spectral resolution better than 0.1 nm in the wavelength range from 170 to 400 nm was carried out by the “HongHu-6” high-altitude balloon that flew to the bottom region of the near-space in September 2022. This experiment was based on the fact that solar FUV-UV penetrates through a complex cross-section window of the upper atmosphere, from outer to near space. The solar FUV-UV deposits energy in the upper atmosphere, which provides a key to answer scientific questions on the most important energy contributor to overall heating sources of the near space and how the near-space environment responds to solar activities. In the wavelength range between 150 and 210 nm, irradiance maps from active regions of the solar corona, the comparative small cross-section of molecular oxygen allows certain wavelengths of the band to arrive at altitudes between 20 and 30 km above the ground, indicating solar flares could directly impact the bottom region of the near space. Solar UV irradiance in the wavelength range 210 – 400 nm is absorbed by the upper atmosphere as a function of wavelength, and energy is deposited vertically in the lower regions of the near space. This experiment historically provides measurement data to fill a gap in the wavelength shorter than 280 nm in the lower regions of the near space. The solar FUV-UV spectrometer (SUVS) is a compact instrument based on improved Roland circle optics to adapt to the “HongHu-6” balloon payload platform. In this paper, we introduce the scientific goals of the solar FUV-UV spectrum measurement experiment, provide information on the SUVS instrument preflight calibration, and present the first results from the flight data.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-024-02396-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142524378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calibration and Release of Magnetograms/Dopplergrams Obtained at the Mt. Wilson 150-Foot Tower Telescope (MWO)","authors":"Roger K. Ulrich,&nbsp;John Boyden,&nbsp;Tham Tran","doi":"10.1007/s11207-024-02390-z","DOIUrl":"10.1007/s11207-024-02390-z","url":null,"abstract":"<div><p>The Mt. Wilson Observatory archive of observations of solar disk magnetic fields, Doppler velocities, and spectral line intensities is a resource for studying the Sun’s state from 1967 to 2013. Instrument changes/upgrades during this time must be considered when interpreting this record. Portions of this record have been previously released. This publication documents the data record in order to allow its independent interpretation. The archive is available through two directory trees which can be accessed at http://sha.stanford.edu/mwo/msm.html. The calibration of the observations is impacted by the solar surface convective flows, which produce offsets for both differential rotation and meridional circulation functions. The effects of these offsets have been reduced in this and other publications by temporal averaging.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-024-02390-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-Term Trends in Subsurface Flows of Solar Cycle 23 to 25","authors":"Rudolf Komm","doi":"10.1007/s11207-024-02397-6","DOIUrl":"10.1007/s11207-024-02397-6","url":null,"abstract":"<div><p>We study the long-term variation of the zonal and meridional flows from Solar Cycle 23 to 25 derived with ring-diagram analysis applied to <i>Global Oscillation Network Group</i> (GONG) and <i>Helioseismic and Magnetic Imager</i> (HMI) Dopplergrams. We focus mainly on the subsurface flows averaged over depths from 2.0 Mm to 11.6 Mm since their long-term variations are sufficiently similar. First, we examine their temporal variations for systematic artifacts. We find that the GONG-derived zonal flows increase almost linearly with time until about 2020, which we correct with a linear regression. Then we determine the average differences between the GONG- and HMI-derived flows. The average offset is <span>(0.15 pm 0.53)</span> m s⁻¹ for the zonal flow and <span>(0.65 pm 0.08)</span> m s⁻¹ for the meridional flow within <span>(pm 30.0^{circ })</span> latitude. The average difference of the meridional flow is nearly constant with latitude in this range, whereas that of the zonal flow varies similarly to that of the magnetic activity. At latitudes of 45.0^∘ and higher, the differences increase and are larger than those at lower latitudes, which is most likely due to the combined effect of different spatial resolution between GONG and HMI and geometric projection effects. Finally, we combine the GONG- and HMI-derived flows and find, as expected, that the solar-cycle variation is the dominant long-term variation. At each latitude within <span>(pm 30.0^{circ })</span>, the meridional-flow pattern appears ahead of the zonal-flow pattern by an average lag of <span>(0.926 pm 0.126)</span> years. The equatorward and poleward branches of the solar-cycle variation occur at 52.5^∘ with the poleward branches present near 60.0^∘ and the equatorward ones at lower latitudes. The zonal flows at 52.5^∘ and 60.0^∘ show an additional trend and decrease by <span>(2.9 pm 0. 3)</span> m s⁻¹ over 11 years. This decrease might nevertheless be related to the solar cycle and imply that the flow amplitudes are anticorrelated with the strength of the associated solar cycle.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"299 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}