Aurora is caused by interaction between the Earth's magnetic field and the solar
wind (a mix of charged particles blowing away from the sun). During solar storms,
enough of these charged particles make it through to the Earth's upper atmosphere that
they interact with the earths natural magnetic field lines. When enough of these
particles collide, energy is released in the form of auroral light. In addition to
creating a pretty light show (mostly in upper latitudes), radio signals scatter off of
these particles and can greatly enhance propagation on 6 meters and above. High levels of
aurora can also make HF propagation via polar routes difficult.
This chart shows X-ray flux levels as measured by the GOES-8 and GOES-10
satellites. The GOES-8 measurements (shown in red) are used to issue "solar
alerts" when X-ray flux levels exceed certain levels. Spikes on the chart
correspond to solar flares. Flares are considered "significant" when flux
levels rise above the "M" level (as shown on the right side of the chart).
These large flares can often wipe out the bands almost immediately and it can take minutes
to hours for the bands to recover. If the bands seem to go dead all of a sudden, it
is always a good idea to check this chart to see if a large flare has occurred recently.
The grey line is a band around the Earth that separates the daylight from
darkness. Propagation along the grey line is very efficient. One major reason
for this is that the D layer, which absorbs HF signals, disappears rapidly on the sunset
side of the grey line, and it has not yet built upon the sunrise side. This map
shows the current position of the grey line terminator.
The following map shows Maximum Usable Frequencies (MUFs) for 3000 kilometer
radio signal paths. More importantly, the current sunspot number (SSN) and Planetary
A-index are updated every 30 minutes on the bottom of this image. Additionally, the
grey line position, auroral ovals, and sun position are provided. Click on the map
for more details on how to use it.
The images below are current views of the sun shown at different wavelengths of
light as taken by SOHO and the Yohkoh soft-Xray telescope. Generally, more bright
regions on the disk indicates more solar activity, which usually leads to higher
solar flux levels (which usually leads to better propagation!). Click on any
thumbnail to view a larger image.
SOHO
- 17.1nm
SOHO
- 19.5nm
SOHO
- 28.4nm
SOHO
- 30.4nm
Yohkoh
Soft X-rays
Sometimes you may see
"CCD Bakeout" instead of the solar disc images. This occurs when NASA does
routine maintenance and calibration on the cameras. For a more technical
explaination, read
NASA's CCD Bakeout explaination.
PROPAGATION --> Hottest new propagation page on the web. Contains many
indicies and reports that are dynamically updated as soon as new information is available.
-- From QSL.NET;
Solar
Terrestrial Activity Report --> By Jan Alvestad -- Recent solar and geomagnetic data (updated daily); Solar
WIND and electron fluence charts (updated daily); Solar cycles 21-23, [Solar cycles 1-20;
Graphical comparison of cycles 21, 22 and 23;
