Real-Time MUF Map
Using this Map
This is a
highly informative map that can be used by amateur and professional radio
communicators to determine maximum usable frequencies for any world-wide path at
the indicated UTC (Zulu) time.
RED contour lines will appear superimposed on the MUF map
if x-rays reach levels capable of producing short wave fadeouts on sunlit paths.
When this occurs, the red contour lines represent the highest frequency (in MHz)
that may be absorbed by the enhanced solar flare x-rays. Use this information
together with our new X-ray Absorption Map to
determine what frequencies and paths may avoid affects of radio signal
absorption during x-ray flares.
The MUF for any 3,000 kilometer path can be determined by
finding the midpoint (or half-way point) of the path and examining
the MUF at that midpoint on the map by finding the labelled MUF contour value.
All contours are given in MHz.
For 4,000 kilometer paths, multiply the given contoured
MUF values by 1.1. The MUF for the given 4,000 km path is then determined at the
midpoint of the desired path.
For longer path lengths, divide the path into equal 3,000
or 4,000 km segments and compute the MUFs corresponding to the two midpoints
that are 1,500 or 2,000 km from each end of the path. Then select the
lower of these two MUFs.
The map shows the radio auroral zones as green bands near the
northern and southern poles. The area within the green bands is known as the
auroral zone. Radio signals passing through these auroral zones will experience
increased signal degradation in the form of fading, multipathing and
absorption.
The radio auroral zones are typically displaced
equatorward from the optical auroral zones (or the regions where visible
auroral activity can be seen with the eye).
The great-circle signal path from the Eastern United
States to Tokyo Japan is shown along with the distance of the path (in km) and
the great-circle bearing from the U.S. to Tokyo (in degrees from north).
If this signal path crosses through the green lines
indicating the position and width of the radio auroral zones, propagation will
be less stable and degraded compared to if the signal never crossed through the
auroral zones. Using your mouse, PROPLAB-PRO will let you plot the great-circle
paths and azimuths between any two points while this display is continually
updated.
The yellow Sun symbol near the equator indicates the location
where the Sun is directly overhead.
The regions of the world where the Sun is exactly rising or
setting is known as the Grayline and is shown as the solid
gray-colored line that is closest to the Sun symbol.
The second solid gray-colored line defines the regions of the world where the
Sun is exactly 12 degrees below the horizon. This line defines the end of
evening twilight. Everything inside of this second line is
experiencing night-time conditions.
The area between the two lines (shaded a lighter shade than the night-time
sector) is known as the grayline and has special significance to
radio communicators. Signals which travel inside the grayline region
often experience significant improvements in propagation because of the loss of
ionization in the D-region as the Sun sets. However, because the higher
F-regions of the ionosphere remain strongly ionized for longer periods of time,
signals with higher frequencies are able to travel to greater distances with
less attenuation when they are within the grayline.
The great-circle path from the eastern U.S. to Japan is also shown
with the accompanying distance (in kilometers) and
bearing (clockwise from north). Notice how this path may
occassionally pass into the influential auroral zones if geomagnetic activity
increases or during the night-times.
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