Ionospheric Map
Data Providers for the World Ionospheric foF2 Map (updated hourly):
The data presented in this page are derived from the automated interpretation of ionograms
from around the world. These data are obtained from the IPS space weather observation network known as IPSNET,
(Australia Pacific Region), the NICT Space Weather Information Centre of Japan (Japanese region),
the Space Physics Group at Rhodes University's Hermanus Magnetic Observatory (South African region),
the Istituto Nazionale di Geofisica e Vulcanolgia, Rome, Italy (Italian Region), the Laboratorio de Ionosfera,
Universidad Nacional de Tucuman, Argentina, (South American Region), and the United States of America Space
Weather Prediction Centre's ftp site. The data available from the SWPC ftp server are contributed by the International
Space Environment Service's (ISES) Regional Warning Centres (RWCs) from around the globe and many ionospheric
observatories operated by the United States Air Force (USAF).
Note:
The foF2 values used in the mapping process are based on the median of the last 2 hours of station
data (4 values per hour). This was done to try to reduce the effect of bad foF2 values. This may mean that
the map may lag actual ionospheric behaviour by about an hour, particularly at local dawn periods.
Validation checking:
Most of the station foF2 data used to create this map is obtained from the
Application:
The above map can be used as a guide to NVIS ionospheric frequency support and to generate real time HF predictions (eg Hourly HAP charts) to assist the HF radio communicator.
A feature of the ionosphere is its ability to reflect radio waves. However, only radio waves
within a certain frequency range will be reflected and this range varies with a number of
factors.
The most widely used instrument for ionospheric measurement is the ionosonde. The ionosonde
is essentially a high frequency radar which sends short pulses of radio energy into the
ionosphere. If the radio frequency is not too high, the pulses are reflected back to earth.
The ionosonde records the time delay between transmission and reception of the pulses. By
varying the frequency of the pulses (typically 1-22MHz), a record is obtained of the time
delay at different frequencies. This record is referred to as an ionogram.
The highest (see note) frequency which the ionosphere will reflect vertically is called foF2.
These foF2 measurements from various sites can be used to create a map of foF2.
Note: The geomagnetic field splits a radio wave in the ionosphere into two separate
components, termed the ordinary (o) and extraordinary (x) waves. It is the o-wave which is
routinely scaled from ionograms.
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