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Metadata Identifier: gov.noaa.ngdc.stp.ionosonde:G10145
MD_DataIdentification
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Ionosonde Stations |
Ionograms are recorded tracings of reflected high frequency radio pulses generated
by an ionosonde. Unique relationships exist between the sounding frequency and the
ionization densities which can reflect it. As the sounder sweeps from lower to higher
frequencies, the signal rises above the noise of commercial radio sources and records
the return signal reflected from the different layers of the ionosphere. These echoes
form characteristic patterns of "traces" that comprise the ionogram.
Radio pulses travel more slowly within the ionosphere than in free space, therefore,
the apparent or "virtual" height is recorded instead of a true height. For frequencies
approaching the level of maximum plasma frequency in a layer, the virtual height tends
to infinity, because the pulse must travel a finite distance at effectively zero speed.
The frequencies at which this occurs are called the critical frequencies. Characteristic
values of virtual heights (designated as h'E, h'F, and h'F2, etc.)
and critical frequencies (designated as foE, foF1, and foF2, etc.) of each layer are
scaled, manually or by computer, from these ionograms. Typically, an ionosonde station
obtains one ionogram recording every 15 minutes. When the scaling is done manually
only the hourly recordings are routinely reduced to numerical data. Modern ionosondes
with computer-driven automatic scaling procedures routinely scale all the
ionograms recorded. The resulting numerical values, along with the original ionograms
and station reports, are archived at five World Data Centers (WDCs) for Ionosphere.
The ionosphere is divided into four broad regions called D,E, F, and topside. These
regions may be further divided into several regularly occurring layers, such as F1
or F2.D Region: The region between about 75 and 95km above the Earth in which the
relatively weak) ionization is mainly responsible for absorption
of high-frequency radio waves. E Region: The region between about 95 and 150km above
the Earth that marks the height of the regular daytime E layer. Other subdivisions
isolating separate layers of irregular occurrence within this region are also labeled
with an E prefix, such as the thick layer, E2, and a highly variable thin layer, Sporadic
E. Ions in this region are mainly O2+. F Region: The region above about 150km in which
the important reflecting layer, F2, is found. Other layers within
this region are also described using the prefix F, such as a temperate-latitude regular
stratification, F1, and a low-latitude, semi-regular stratification, F1.5. Ions in
the lower part of the F layer are mainly NO+ and are predominantly O+ in the upper
part. The F layer is the region of primary interest for radio communications.
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SV_Identification
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Ionosonde Stations |
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NASA/GCMD Data Center Keywords |
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NASA/GCMD Earth Science Keywords |
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NASA/GCMD Location Keywords |
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Citation URL |
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http://spidr.ngdc.noaa.gov |
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No Title |
Justin Mabie |
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
of Commerce
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Space and Terrestrial Weather Specialist |
Justin.Mabie@noaa.gov |
pointOfContact |
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Justin Mabie |
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
of Commerce
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ionosonde@noaa.gov |
distributor |
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User Services |
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
of Commerce
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ngdc.info@noaa.gov |
originator |
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ftp://ftp.ngdc.noaa.gov/ionosonde |
Index of STP/Ionosphere |
ftp characteristics of Ionospheric data |
download |
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http://spidr.ngdc.noaa.gov |
Ionosonde Data |
Information, search capabilities and data downloads |
information |
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http://www.ngdc.noaa.gov/stp/IONO |
Ionosonde Data Archived at NGDC |
Ionosonde Data |
information |
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http://www.ngdc.noaa.gov/stp/solar/solardataservices.html |
Solar Data |
Solar Home page |
information |
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Bounding Box |
Temporal Extent |
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-180 |
180 |
90 |
-90 |
1958-01-01 |
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via ftp: SAO, EDP GIF, PNG, MMM, 16C, RSF, SDF, GRM, DFT and SKY via Spidr: ASCII,
XML Matlab
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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.
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