Solar Features - Solar Flares
Browse image of sun from the NOAA Solar X-ray Imager (SXI) for 07-March-2012 with the X-ray Sensor (XRS) superimposed below the image.
A solar flare is a short-lived sudden increase in the intensity of radiation emitted in the neighborhood of sunspots. For many years it was best monitored in the H-alpha wavelength and occurs in the chromosphere, though occasionally white light flares are seen in the photosphere. In modern times the solar X-ray wavelengths are monitored via satellite for solar flares. Flares are characterized by a rise time of the order of minutes and a decay time of the order of tens of minutes. The total energy expended in a typical flare is about 1030 ergs; the magnetic field is extraordinarily high reaching values of 100 to 10,000 gauss. Optical flares in H-alpha are usually accompanied by radio and X-ray bursts and occasionally by high-energy particle emissions.
The optical brightness and size of the flare are indicated by a two-character code called "importance." The first character, a number from 1 to 4, indicates the apparent area. For areas of less than 1, an "S" is used to designate a subflare. The second character indicates relative brilliance: B for bright, N for normal and F for faint. A general discussion of solar flares is found in Svestka [1976]. The NOAA National Centers for Environmental Information (formerly NGDC) holds archives for about 80 stations, covering the period 1938 to the present. Currently 5 stations send their data to NGDC Boulder on a routine monthly basis -- the current main observing emphasis for Space Weather has transitioned to Coronal Mass Ejections (CMEs) which directly impact the Earth's geomagnetic field. Solar flares impact the Earth's upper atmosphere and can eject high energy particles that can cause satellite failures. The flare reports were processed and published in the monthly report "Solar-Geophysical Data" and in a different format in the IAU "Quarterly Bulletin on Solar Activity."
The optical brightness and size of the flare are indicated by a two-character code called "importance." The first character, a number from 1 to 4, indicates the apparent area. For areas of less than 1, an "S" is used to designate a subflare. The second character indicates relative brilliance: B for bright, N for normal and F for faint. A general discussion of solar flares is found in Svestka [1976]. The NOAA National Centers for Environmental Information (formerly NGDC) holds archives for about 80 stations, covering the period 1938 to the present. Currently 5 stations send their data to NGDC Boulder on a routine monthly basis -- the current main observing emphasis for Space Weather has transitioned to Coronal Mass Ejections (CMEs) which directly impact the Earth's geomagnetic field. Solar flares impact the Earth's upper atmosphere and can eject high energy particles that can cause satellite failures. The flare reports were processed and published in the monthly report "Solar-Geophysical Data" and in a different format in the IAU "Quarterly Bulletin on Solar Activity."
Dataset Citation
Cite this dataset when used as a source.
Dataset Identifiers
- solarFeatures
ISO 19115-2 Metadata
gov.noaa.ngdc.stp.solar:solar-features_solar-flares
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Distributor | William Denig DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce (303) 497-6323 solar.ngdc@noaa.gov |
Dataset Point of Contact | William Denig DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce (303) 497-6323 solar.ngdc@noaa.gov |
Coverage Description | Data acquired from NOAA observing systems plus other datasets provided through the World Data Service for Geophysics, Boulder. |
Time Period | 1938-01-01 to Present |
Spatial Bounding Box Coordinates |
West: -180
East: 180
South: -90
North: 90
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Spatial Coverage Map |
Documentation links not available. |
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Dataset Progress Status | Under development - data is currently in the process of being created |
Data Update Frequency | Annually |
Supplemental Information | Collection consists of tabular lists and information related to solar flares. |
Purpose | To provide scientific data stewardship of solar-terrestrial datasets in compliance with NOAA Administrative Order (NAO) 212-15, "Management of Environmental and Geospatial Data and Information", dated 04 Nov 10. Scientific Data Stewardship includes the Archive, Access, and Assessment (AAA) of operational and related solar and space environmental datasets. |
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Theme keywords |
NASA/GCMD Earth Science Keywords; Olsen, L.M., G. Major, K. Shein, J. Scialdone, R. Vogel, S. Leicester, H. Weir, S. Ritz, T. Stevens, M. Meaux, C.Solomon, R. Bilodeau, M. Holland, T. Northcutt, R. A. Restrepo, 2007 . NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 6.0.0.0.0.
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Data Center keywords |
Global Change Master Directory (GCMD) Data Center Keywords
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Platform keywords |
NASA/GCMD Platform Keywords; Olsen, L.M., G. Major, K. Shein, J. Scialdone, R. Vogel, S. Leicester, H. Weir, S. Ritz, T. Stevens, M. Meaux, C.Solomon, R. Bilodeau, M. Holland, T. Northcutt, R. A. Restrepo, 2007 . NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 6.0.0.0.0.
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Instrument keywords |
NASA/GCMD Instrument Keywords; Olsen, L.M., G. Major, K. Shein, J. Scialdone, R. Vogel, S. Leicester, H. Weir, S. Ritz, T. Stevens, M. Meaux, C.Solomon, R. Bilodeau, M. Holland, T. Northcutt, R. A. Restrepo, 2007 . NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 6.0.0.0.0.
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Place keywords |
NASA/GCMD Location Keywords; Olsen, L.M., G. Major, K. Shein, J. Scialdone, R. Vogel, S. Leicester, H. Weir, S. Ritz, T. Stevens, M. Meaux, C.Solomon, R. Bilodeau, M. Holland, T. Northcutt, R. A. Restrepo, 2007 . NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 6.0.0.0.0.
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Global Change Master Directory (GCMD) Project Keywords
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Lineage Statement | Authoritative data provided by various institutions. |
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Last Modified: 2015-10-02
For questions about the information on this page, please email: solar.ngdc@noaa.gov
For questions about the information on this page, please email: solar.ngdc@noaa.gov