Solar activity and HF/VHF propagation page
Information about radio propagation on HF and VHF for Hams and SWL.
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Trends of the solar flux index (SFI), Energetic particles monitor Estimated planetary K-index. sunspot number (SN) and number of Data from the last 2 weeks. C-M-X solar flares during the last 30 days.
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.
An ionogram is a
display of the data produced by an ionosonde. It is a graph of the
virtual height of the ionosphere plotted against frequency. Ionograms are often
converted into electron density profiles. Data from ionograms may be used to measure
changes in the Earth's ionosphere due to space weather events.
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/
| 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._________________________________________________________________________________________________________________________
Though the sun is currently in the peak year of its 11-year solar weather cycle, our closest star has been rather quiet over all, scientists say.
This year's solar maximum is shaping up to be the weakest in 100 years and the next one could be even more quiescent, scientists said Thursday (July 11, 2013).
"It's the smallest maximum we've seen in the Space Age," David Hathaway of NASA's Marshall Space Flight Center in Huntsville, Ala., told reporters in a teleconference. [Solar Max: Amazing Sun Storm Photos of 2013]
During a solar maximum, the number of sunspots increases. These dark temporary regions on the surface of the sun are thought to be caused by interplay between the sun's plasma and its magnetic field. Sunspots are the source of the solar flares and ejections that can send charge particles hurtling toward Earth, which can damage satellites, surge power grids, cause radio blackouts and, more benignly, produce dazzling auroras above the planet.
About every 11 years, the sun goes through a cycle defined by an increasing and then decreasing number of sunspots. Solar Cycle 24 has been underway since 2011 and its peak was expected in 2013, but there have been fewer sunspots observed this year compared with the maximums of the last several cycles.
Giuliana de Toma, a scientist at the High Altitude Observatory in Colorado, said the sunspots occurring during a calm maximum have the same brightness and area as the ones observed during a more turbulent peak.
"We just have fewer of them and this is normal," de Toma said during Thursday's briefing. "This is why weak cycles are weak."
The quiet maximum is allowing scientists to test their knowledge of how the sun works and hone their predictions of the strength of future solar cycles.
"You might think that having a small cycle is disappointing to us but it's quite the contrary," Hathaway said.(news from www.space.com)
Click to see 400 year of sunspot observation. _________________________________________________________________________________________________________________________
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