Solar Features - Solar Flares

Metadata Updated: October 13, 2020

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."

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License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Date October 2, 2015
Metadata Created Date October 13, 2020
Metadata Updated Date October 13, 2020
Reference Date(s) August 10, 2014 (publication)
Frequency Of Update annually

Metadata Source

Harvested from NGDC STP Solar

Graphic Preview

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.

Additional Metadata

Resource Type Nongeographicdataset
Metadata Date October 2, 2015
Metadata Created Date October 13, 2020
Metadata Updated Date October 13, 2020
Reference Date(s) August 10, 2014 (publication)
Responsible Party DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce (Point of Contact)
Contact Email
Access Constraints Access Constraints: None Use Constraints: None Distribution Liability: While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
Bbox East Long 180
Bbox North Lat 90
Bbox South Lat -90
Bbox West Long -180
Coupled Resource
Frequency Of Update annually
Graphic Preview Description 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.
Graphic Preview File https://www.ngdc.noaa.gov/stp/space-weather/solar-data/solar-features/solar-flares/documentation/miscellaneous/browse-graphic_sxi_20120307.jpg
Graphic Preview Type Joint Photographic Experts Group (jpg) format
Guid gov.noaa.ngdc.stp.solar:solar-features_solar-flares
Harvest Object Id 0db1adf4-cde2-4661-b4d0-6a4f8c62bb61
Harvest Source Id b204ed61-c7b3-476c-a585-9ee0dda0a6e3
Harvest Source Title NGDC STP Solar
Licence
Metadata Language
Metadata Type geospatial
Progress underDevelopment
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 1938-01-01
Temporal Extent End Present

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