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.
"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.
Cite this dataset when used as a source.
- ID not available.
gov.noaa.ngdc.stp.ionosonde:G10145
Download Data |
|
Other Access | |
Distribution Formats |
|
Distributor | Justin Mabie Space and Terrestrial Weather Specialist DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce (303) 497-6135 Justin.Mabie@noaa.gov |
Dataset Point of Contact | Justin Mabie Space and Terrestrial Weather Specialist DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce (303) 497-6135 Justin.Mabie@noaa.gov |
Time Period | 1958-01-01 to Present |
Spatial Bounding Box Coordinates |
West:-180
East:180
South:-90
North:90
|
Spatial Coverage Map |
General Documentation |
|
Publication Dates |
|
Dataset Progress Status | Under development - data is currently in the process of being created |
Data Update Frequency | Daily |
Supplemental Information |
Every Ionosonde station has it's own metadata record in Spidr and also in the Ionosonde
Record Set here in the NMMR
|
Purpose | To produce Ionograms |
Use Limitations |
|
Originators |
|
Publishers |
|
Theme keywords | NASA/GCMD Earth Science Keywords
|
Data Center keywords | Global Change Master Directory (GCMD) Data Center Keywords
|
Place keywords | NASA/GCMD Location Keywords
|
Project keywords | Global Change Master Directory (GCMD) Project Keywords
|
Use Constraints |
|
Access Constraints |
|
Fees |
|
Processing Steps |
|
Last Modified: 2015-09-18
For questions about the information on this page, please email:Justin.Mabie@noaa.gov