Solar conditions

Solar-Terrestrial data

The Solar Widget is based on data from the United States National Oceanic and Atmospheric Administration (NOAA). The raw data is publicly available -in text format- here.

To make any sense of the raw data takes some computational power. After a some trial-and-error and experimenting I came up with an algorithm that I feel represents the HF propagation conditions quite well. So now is the time to go public with my widget.

Please feel free to test and try and contact me with remarks, suggestions, errors or whatever else is relevant.

Solar widget

The RigReference Solar Widget gives an indication of the conditions on the various ham bands, for both day and night time.

How to use...

...on WordPress blogs?

If you're using WordPress, you're in luck. We've developed a WordPress solar-plugin which is easy to install and requires zero technical knowlegde. The plugin also allows you to switch between widget layouts from the WordPress admin pages.

...on all other sites?

For all other sites, incorporating the solar widget in your own site requires you copy-paste the code below into your own page -at the location where you want the widget to be displayed.

Conditions widget in wide format
Solar conditions - wide image
Plain html:
Conditions widget in tall format
Solar conditions - tall image
Plain html:
Conditions widget for the Navtex band, 600 meter / 518 kHz
Solar conditions for Navtex band
Custom made for
Plain html:
Conditions widget for the CB / 11 meter band
Solar conditions for CB band
Plain html:

HF-band conditions (day/night)

These are the values I calculated from the raw NOAA data. There isn't any golden rule for calculation propagation conditions. I've put together an algorithm based on data from different sources. /p>

Band Day Night
600 meter Good (96) Good (169)
160 meter Fair (58) Good (92)
80 meter Poor (49) Fair (75)
40 meter Poor (43) Fair (63)
20 meter Poor (39) Fair (55)
10 meter Poor (36) Poor (48)
6 meter Poor (35) Poor (46)

Paul Herrman (N0NBH) has a fantastic site if you're into solar and weather data. I've used his info a lot.

Latest measurement - raw data

This is the latest measurement from NOAA. I use these values to estimate current propagation conditions.

Parameter Value Remarks
Time 2024-07-21 12:05:00 UTC Time of measurement
Ai 7 A-index
Ki 1 Planetary K-index
SFi 207 Solar Flux index
Proton flux 1.8316727876663
Electron flux 19.687671661377
X-Ray C2.2
Calculated conditions
Signal/Noise level S0-1 Background S/N level
Geomagnetic field Very quiet Ranges from Very quiet to Storm
MUF 38 MHz Maximum Usable Frequency

Historic data

Solar activity as recorded by NOAA of the past 7 days. Solar flares can be seen especially in the K-index graph as large spikes. Shortwave propagation can be severely affected by flares, causing higher noise levels and weaker signals.

Ai indicates a daily average level for geomagnetic activity. Values range from about 0 to 400. Ai is the average of eight 3-hour Ki values and provides a level of instability in the earth's geomagnetic field. Instability is greatest when both Ai and Ki are high. This can cause HF-signals to fade and paths to open and close with little warning. A high Ki and low Ai indicates an abrupt disturbance in the geomagnetic field, resulting in intense but brief disruptions in HF-propagation. Ai is recorded once a day.

Ki indicates the disturbance in the horizontal component of the earth's magnetic field. Values range from 0 to 9 and are based on 3-hour interval measurements in nT (nano Tesla). The higher the Ki-value, the more static and interference you can expect. Ki-values have more impact at higher latitudes (closer to the poles).

SFi (Solar Flux Index) is the solar radiation measured at 2800 MHz (10.7cm) and gives a good indication of the F-layer ionization. The higher the number, the more the ionization, which gives us nice DX openings on HF-bands. Higher bands are less affected by SFi. Measurements range from about 60 to 300 and are recorded 3 times per day. The up and down motion is caused by the rotation of the sun which has a cycle of 28 days.