riometer
/riːˈɒmɪtə/Atmospheric Physics
noun
An instrument for measuring the absorption of cosmic radio waves by the ionosphere.
- The riometer operates by comparing the measured radio noise with a long-term average value; the difference corresponds to the amount of ionospheric absorption..
Origin
1950s; earliest use found in Geophysics & IGY. From the initial letters of relative ionospheric opacity + -meter.