Solar Radio

Metadata Updated: November 12, 2020

Scientists monitor the structure of the solar corona, the outer most regions of the Sun's atmosphere, using radio waves (100’s of MHz to 10’s of GHz). Variations in the radiowave spectrum reveal characteristics of the corona and upper chromosphere in terms of altitude profile for the local plasma temperature, density and magnetic field. Typically, the lower the frequency then the higher the height of origin. The frequency, like the solar electron density, decreases uniformly outwards with 245 MHz originating high in the corona whereas 15,400 MHz originates in the low corona. Radio bursts are associated with solar flares. The delay at Earth of the different radio frequencies during burst events is due to the outward movement of the source. Bursts can have temperatures of 10xE12 degrees Kelvin. Large bursts last 10 to 20 minutes on average. Longer radio noise storms of persistent and variable high levels of radiation originate in sunspot groups, areas of large, intense magnetic fields. These storms are strongly circularly polarized due to the intense magnetic fields. The microwave wavelength 2800 MHz daily radio flux correlates highly with the daily sunspot number and the two databases are used interchangeably. The 2800 MHz, or 10.7 cm, responds to the same conditions that produce changes in the visible and X-ray wavelengths. Schmahl and Kundu (1995) find that the solar radio fluxes in the spectral range 1000-9400 MHz correlate well with the total solar irradiance. The intermediate frequencies (at 2800 and 3750 MHz) are produced mainly by free-free gyroresonance emission from sunspot structures, while 1000 and 9400 MHz flux are produced mainly by free-free processes from structures associated with plages. They can distinguish plage-associated emission from spot-associated emission in the time series of microwave flux, both contributing opposing effects on the total solar irradiance.

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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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Metadata Date October 2, 2015
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) October 14, 2012 (publication)
Frequency Of Update annually

Additional Metadata

Resource Type Nongeographicdataset
Metadata Date October 2, 2015
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) October 14, 2012 (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 the sun in x-rays during a solar radio burst(
Graphic Preview File
Graphic Preview Type Joint Photographic Experts Group (jpg) format
Harvest Object Id c7facb22-8c38-4da5-8ac1-3d02d8dd59ff
Harvest Source Id 71a80367-917c-4f7c-a316-e2fff4d16c62
Harvest Source Title NGDC STP Solar
Metadata Language eng; U.S.A.
Metadata Type geospatial
Progress underDevelopment
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 1955-07-01
Temporal Extent End 2010-11-24

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