kth.sePublications KTH
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Solar Soft X-ray Irradiance Variability, I: Segmentation of Hinode/XRT Full-Disk Images and Comparison with GOES (1-8 angstrom) X-Ray Flux
Young Innovators Educ Serv Pvt Ltd YIESPL, Bangalore 560040, Karnataka, India.;Nagoya Univ, Inst Space Earth Environm Res ISEE, Nagoya, Aichi, Japan..
Nagoya Univ, Inst Space Earth Environm Res ISEE, Nagoya, Aichi, Japan.;Indian Inst Astrophys, Bangalore 560034, Karnataka, India..
Nagoya Univ, Inst Space Earth Environm Res ISEE, Nagoya, Aichi, Japan..
Nagoya Univ, Inst Space Earth Environm Res ISEE, Nagoya, Aichi, Japan..
Show others and affiliations
2021 (English)In: Solar Physics, ISSN 0038-0938, E-ISSN 1573-093X, Vol. 296, no 4, article id 71Article in journal (Refereed) Published
Abstract [en]

It is of great interest and importance to study the variabilities of solar EUV, UV and X-ray irradiance in heliophysics, in Earth's climate, and space weather applications. A careful study is required to identify, track, monitor and segment the different coronal features such as active regions (ARs), coronal holes (CHs), the background regions (BGs) and the X-ray bright points (XBPs) from spatially resolved full-disk images of the Sun. Variability of solar soft X-ray irradiance is studied for a period of 13 years (February 2007-March 2020, covers Solar Cycle 24), using the X-Ray Telescope on board the Hinode (Hinode/XRT) and GOES (1 - 8 angstrom). The full-disk X-ray images observed in Al_mesh filter from XRT are used, for the first time, to understand the solar X-ray irradiance variability measured, Sun as a star, by GOES instrument. An algorithm in Python has been developed and applied to identify and segment coronal X-ray features (ARs, CHs, BGs, and XBPs) from the full-disk soft X-ray observations of Hinode/XRT. The segmentation process has been carried out automatically based on the intensity level, morphology and sizes of the X-ray features. The total intensity, area, and contribution of ARs/CHs/BGs/XBPs features were estimated and compared with the full-disk integrated intensity (FDI) and GOES (1 - 8 angstrom) X-ray irradiance measurements. The XBPs have been identified and counted automatically over the full disk to investigate their relation to solar magnetic cycle. The total intensity of ARs/CHs/BGs/XBPs/FD regions are compared with the GOES (1 - 8 angstrom) X-ray irradiance variations. We present the results obtained from Hinode/XRT full-disk images (in Al_mesh filter) and compare the resulting integrated full-disk intensity (FDI) with GOES X-ray irradiance. The X-ray intensity measured over ARs/CHs/BGs/XBPs/FD is well correlated with GOES X-ray flux. The contributions of the segmented X-ray features to FDI and X-ray irradiance variations are determined. It is found that the background and active regions have a greater impact on the X-ray irradiance fluctuations. The mean contribution estimated for the whole observed period of the background regions (BGs) will be around 65 +/- 10.97%, whereas the ARs, XBPs and CHs are 30 +/- 11.82%, 4 +/- 1.18% and 1 +/- 0.52%, respectively, to total solar X-ray flux. We observed that the area and contribution of ARs and CHs varies with the phase of the solar cycle, whereas the BGs and XBPs show an anti-correlation. We find that the area of the coronal features is highly variable suggesting that their area has to be taken into account in irradiance models, in addition to their intensity variations. The time series results of XBPs suggest for an existence of anti-correlation between the number of XBPs and the sunspot numbers. It is also important to consider both the number variation and the contribution of XBPs in the reconstruction of total solar X-ray irradiance variability.

Place, publisher, year, edition, pages
Springer Nature , 2021. Vol. 296, no 4, article id 71
Keywords [en]
Sun: X-ray radiation, Sun: corona, Sun: coronal features, Sun: X-ray bright points
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:kth:diva-295451DOI: 10.1007/s11207-021-01785-6ISI: 000641806200001Scopus ID: 2-s2.0-85104560896OAI: oai:DiVA.org:kth-295451DiVA, id: diva2:1562506
Note

QC 20210608

Available from: 2021-06-08 Created: 2021-06-08 Last updated: 2022-06-25Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textScopus

Authority records

Giono, Gabriel

Search in DiVA

By author/editor
Giono, Gabriel
By organisation
Space and Plasma Physics
In the same journal
Solar Physics
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 221 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf