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Sudden Ionospheric Disturbances (SID)

Metadata Updated: November 12, 2020

Sudden ionospheric disturbances (SID) are caused by solar flare enhanced X-rays in the 1 to 10 angstrom range. Solar flares can produce large increases of ionization in the D-region of the ionosphere over the daylit hemisphere of the Earth. SID's typically begin simultaneously or a few minutes after the start of a solar flare, and can have a time duration somewhat longer than the flare with a rise time more rapid than the decay time.Types of SIDs are SCNA--sudden cosmic noise absorption is a riometer-detected sudden daytime absorption increases; SEA--sudden enhancement of atmospherics are increases in signal strength on wideband equipment operated in the VLF, 10 to 50 KHz frequency range; SES--sudden enhancement of signal, observed on VLF frequencies in the 15 to 50 KHz range are nearly identical to SEA except that the receivers are narrow-band receivers designed to pick up man-made VLF transmission. Like SEA, signal strength increase is the SID indicator; SFD--sudden frequency deviation is the sudden increase of high frequency radiowaves which reaches a peak, and then decays back to the transmitting frequency; SPA--sudden phase anomaly is an abrupt shift in the phase of a radio signal on VLF frequencies received by ionospheric reflection; SWF--short wave fadeouts are abrupt decreases of radio signal strength observed at VLF frequencies.Tables of SIDs include the date; beginning, maximum and ending times; type of SID; importance on a scale of 1- to 3+ and the corresponding solar flare, if known.

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Metadata Date September 18, 2015
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 1958 (publication)
Frequency Of Update monthly

Metadata Source

Harvested from NGDC STP Ionosphere

Additional Metadata

Resource Type Dataset
Metadata Date September 18, 2015
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 1958 (publication)
Responsible Party Unknown
Contact Email
Guid gov.noaa.ngdc.stp.ionosphere:G00581
Access Constraints Use Constraints: None, Access Constraints: No Constraints
Bbox East Long 180.000000
Bbox North Lat 90.000000
Bbox South Lat -90.000000
Bbox West Long -180.000000
Coupled Resource
Frequency Of Update monthly
Harvest Object Id f24f1077-3f2e-4c59-b3f1-ea9adf430914
Harvest Source Id 369678b9-92fb-448e-8f6a-1654fe221897
Harvest Source Title NGDC STP Ionosphere
Licence 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.
Metadata Language eng; USA
Metadata Type geospatial
Progress underDevelopment
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 1958-01-01

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