- Riometer
A riometer ("r"elative "i"onospheric "o"pacity meter) is an instrument used to quantify the amount of
ionospheric absorption in the atmosphere. [ cite book | first=R.D | last=Hunsucker |coauthors= J.K Hargreaves| year=2003 | title=The High-Latitude Ionosphere and its Effects on Radio Propagation|publisher=Cambridge University Press |] As the name implies, a riometer measures the ``opacity" of the ionosphere to radio noise emanating from distant stars and galaxies. In the absence of any ionospheric absorption, this radio noise, averaged over a sufficiently long period of time, forms a "quiet-day curve." Increased ionization in the ionosphere will cause absorption of radio signals (both terrestrial and extra-terrestrial), and a departure from the quiet-day curve. The difference between the quiet-day curve and the riometer signal is an indicator of the amount of absorption, and is measured indecibels . Riometers are generally passive radioantenna operating in theVHF radio frequency range (~30 MHz).Notes and references
reflist
External Links
[http://www.haarp.alaska.edu/haarp/Rio.html HAARP 30 MHz riometer]
Wikimedia Foundation. 2010.
