Ionograms from Lualualei on Oahu

The Ionograms posted by the US Navy on Oahu are undoubtedly our best source of information about current local ionospheric conditions.

1 - Click the List of Recent Ionograms button & scroll to the bottom of the list.
2 - Open the latest (last) ionogram listed. (GMT/UTC Time)
3 - The foF2 and foF1 critical frequencies will be in the upper left corner.
4 - Compare them with the Statewide NVIS table below.

(It can take 10 seconds or more to load)

Using the Ionogram to predict
the strongest statewide NVIS frequency:
If foF2 is aboveand foF1 is N/A or belowuse this frequency
7.900 mhz6.400 mhz7.188 mhz
7.800 mhz6.38 mhz7.088 mhz
5.900 mhz4.800 mhz5.371.5 mhz
4.300 mhz3.500 mhz3.880 mhz
2.000 mhz1.690 mhz1.857 mhz
"The selection of an appropiated working frequency is essential for a successful operation in NVIS. As a general rule, we will choose a frequency 10% below the ionosphere's F2 layer critical frequency (foF2) at a given time."