Solar activity and HF/VHF propagation page.
Information about radio propagation on HF and VHF for Hams and SWL.
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30 days solar cycle activity. Solar activity forecast for next 27 days. Estimated planetary K-index.
Understanding solar indices by Ian P., G3YWX PDF document.(538 kbyte)
At 18 minutes past the hour, radio stations WWV and WWVH
broadcast the latest solar flux number, the average planetary A-Index
and the latest mid latitude K-Index. In addition, they broadcast a descriptive account of the condition of the geomagnetic field and a
forecast for the next three hours. You should keep in mind that the A-Index is a description of what happened yesterday. Strictly
speaking, the K-Index is valid only for mid latitudes.
Pass solar cycles.
Digisonde Station List.
GOES Solar X-ray Flux.
Click here to see the most recent image of the far side of the sun at http://gong.nso.edu/data/farside/
Click here to see the most recent image of the far side of the sun http://soi.stanford.edu/data/full_farside/latest.syn.gif
Click here to see the most recent spherical map of the Sun as it currently appears.
This movie shows a spherical map of the Sun as it currently appears,
formed from a combination of the latest STEREO Ahead and Behind beacon
images. The movie starts with the view of the Sun as seen from Earth, with
the 0 degree meridian line in the middle. The map then rotates through 360
degrees to show the part of the Sun not visible from Earth. The black wedge
shows the part of the Sun not yet visible to the STEREO spacecraft.
| VHF Aurora |
144 MHz E-Skip
Current solar images.
http://www.swpc.noaa.gov/ftpdir/latest/SRS.txt Solar Region Summary.
Real time solar wind.
Solar wind velocity. Solar wind density.
Aurora (also known as "aurora borealis" or "northern lights") 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.
Real Time Real Time Northern Hemisphere Southern Hemisphere Auroral Activity. Auroral Activity.
Northern hemisphere auroral potential. _____________________________________________________________________________________________________________ Grey line map - One (click here) Grey line map - Two (click here) The grey line is a band around the Earth that separates the daylight from darkness. Radio 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. Ham radio operators and shortwave listeners can optimize long distance communications to various areas of the world by monitoring this area as it moves around the globe. This map shows the current position of the grey line terminator. _____________________________________________________________________________________________________________
Click here to see the total Electron Content. *** 1 TECU = 10E+16 electrons per square meter _____________________________________________________________________________________________________________Near real time MUF map.
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.
Near real time MUF map.
Near-Real-Time F2-Layer Critical Frequency Map. _____________________________________________________________________________________________________________ Near-Real-Time Map of the F2-Layer Height Maximum. The following image is a recent global map indicating the altitude above the surface of the Earth where the ionospheric electron density reaches a maximum. It is known as the height maximum of the F2 layer (or hmF2) and is given in kilometers above the surface of the Earth. It is also a map showing the current location of the auroral ovals, the sunrise/sunset terminator and the regions of the world where the sun is 12 degrees below the horizon (which estimates the gray-line corridor where HF propagation is usually enhanced).
Near-Real-Time Map of the F2-Layer Height Maximum ____________________________________________________________________________________________________________ Near real time E layer critical frequency map. The following image is a recent high-resolution global map of E-layer critical frequencies. This corresponds to the maximum radio frequency that can be reflected by E-region of the ionosphere at vertical incidence (that is, when the signal is transmitted straight up into the ionosphere). It is also a map showing the current location of the auroral ovals, the sunrise/sunset terminator and the regions of the world where the sun is 12 degrees below the horizon (which estimates the gray-line corridor where HF propagation is usually enhanced) Radio communicators most often do not want their signals to spend very much time in this region of the ionosphere. Signals which are reflected within the E-region spend the greatest time in the E-region and are accordingly attenuated the most. Signals that exceed the E-layer critical frequency (and are vertically incident) will penetrate the E-region and travel toward the F-regions. Signals that are below the critical E-layer frequency will always be reflected back to the Earth.
Near real time E layer critical frequency map. __________________________________________________________________________________________________________________
Cycle 21, 22, 23 and 24.
Cycle 24 Prediction._________________________________________________________________________________________________________________________
Click to see 400 year of sunspot observation. _________________________________________________________________________________________________________________________
Also you most to see.
e-mail: CO8TW e-mail address
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