Description

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.

General Information

• This data is described at

  http://catalog.data.gov/dataset/ionosonde-stations Do you think this data is incorrect? Let us know

• This data is published by

  National Oceanic and Atmospheric Administration, Department of Commerce Do you think this data is incorrect? Let us know

Legal Information

• The rights statement is at

  http://catalog.data.gov/dataset/ionosonde-stations Do you think this data is incorrect? Let us know

• Outside the US, this data is available under

  Creative Commons CCZero Do you think this data is incorrect? Let us know

• There are

  yes, and the rights are all held by the same person or organisation Do you think this data is incorrect? Let us know

• The content is available under

  Creative Commons CCZero Do you think this data is incorrect? Let us know

• This data contains

  no data about individuals Do you think this data is incorrect? Let us know

Practical Information

• The data appears in this collection

  http://catalog.data.gov/organization/noaa-gov Do you think this data is incorrect? Let us know

• This data changes

  at least daily Do you think this data is incorrect? Let us know

• The data is

  backed up offsite Do you think this data is incorrect? Let us know

Technical Information

• Releases of this data are listed at

  http://catalog.data.gov/api/rest/package/ionosonde-stations Do you think this data is incorrect? Let us know

• The format of this data is

  a standard open format Do you think this data is incorrect? Let us know

Social Information

• The documentation includes machine-readable data for

  title Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  description Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  identifier Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  landing page Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  release frequency Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  publisher Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  distribution(s) Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  release date Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  modification date Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  temporal coverage Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  spatial/geographical coverage Do you think this data is incorrect? Let us know

• The documentation about each distribution includes machine-readable data for

  release date Do you think this data is incorrect? Let us know

• The documentation about each distribution includes machine-readable data for

  a URL to access the data Do you think this data is incorrect? Let us know

• The documentation about each distribution includes machine-readable data for

  a URL to download the dataset Do you think this data is incorrect? Let us know

• Find out how to contact someone about this data at

  http://catalog.data.gov/dataset/ionosonde-stations Do you think this data is incorrect? Let us know

• Find out how to suggest improvements to publication at

  http://www.data.gov/issue/?media_url=http://catalog.data.gov/dataset/ionosonde-stations Do you think this data is incorrect? Let us know