Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Skip to content

Measurements of the Absorptive Properties of the Ionosphere

Metadata Updated: November 12, 2020

Absorption of radio waves occurs when electrons responding to the wave fields collide with and transfer energy to the neutral particles. A study of ionospheric absorption yields information on both the D and E regions, where both electrons and neutral particles exist in sufficient quantity to produce significant absorption. Knowledge of D region characteristics is unattainable from normal sweep-frequency ionograms because absorption prevents the return of a detectable reflected signal. In practice, absorption characteristics are studied primarily in connection with radio communications applications. A riometer (relative ionospheric opacity meter) is a detector that measures the absorptive properties of the ionosphere. This directional detector is oriented in a fixed direction relative to the Earth (usually vertical) and measures the incident cosmic radio noise at a single frequency between 8 MHz and 120 MHz (usually 20, 30, or 60 MHz). During the course of each sidereal day, the riometer receives noise from all celestial longitudes. Due to the general constancy of cosmic radio noise, the signal will be constant except for a large-scale, small-amplitude, daily solar effect which regresses through the observations at the rate of 1 day per year (4 minutes earlier each day). Deviations of observed riometer signal power are primarily attributable to ionospheric variations particularly in the D and E regions. This method is particularly useful during radio blackout (high absorption) since it involves the use of higher frequency signals that are not completely absorbed. The Alaskan Chain Riometer data was discontinued, in analog form, December 31, 1990. The Data Center still receives riometer data from Kiruna. The publication includes magnetograms, k-indices, all-sky camera data, and riometer data. It is published quarterly. We also receive some riometer data from Syowa Station. The data are collections of several years of data and the publication (JARE DATA REPORTS) are sent by the National Institute of Polar Research, Tokyo Japan. These publications only have numeric values. All riometer data are in paper form and are stored off site. Most of the data are ''strip charts'' which record the variations on paper rolls. This data base is mostly a collection of the different charts and publications. No additional quality control is done by the NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) here in Boulder. Data requested are electrostatic copies of the appropriate portion of a chart of publication.

Access & Use Information

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.

Downloads & Resources

No file downloads have been provided. The publisher may provide downloads in the future or they may be available from their other links.

Dates

Metadata Date September 18, 2015
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 1964 (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, 1964 (publication)
Responsible Party Unknown
Contact Email
Guid gov.noaa.ngdc.stp.ionosphere:G00569
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 2a12440d-313c-4f91-910f-25c7a0eefbf4
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 1963-01-01
Temporal Extent End 1990-12-31

Didn't find what you're looking for? Suggest a dataset here.