The solar-terrestrial data image shows several indexes. They are an indicator of the HF and VHF conditions and may be used for predictions. Some of the values are measured, others are calculated. The frequency differs from once daily to every 15 minutes.

SFI: Solar Flux Index. Radiation intensity measured at 2800 MHz. This is an indicator for the ionization of the F-Layer. The higher, the better.

SN: Sunspot Number. This is not measured, but computed. Value between 0 and 250. It correlates loosely the the SFI.

A: Planetary A Index. Average level of geomagnetic activity, value between 0 and 400. To be used together with K.

K: Planetary K Index. Measures the disturbance of the horizontal component of earth's magnetic field. Values from 0 to 9. To be used together with A.

Interpretation of A and K: Both high indicates geomagnetic field is unstable, and HF signals are prone to sudden fades, and some paths may close while others open up abruptly and with little warning. High K index/Low A indicates a sudden, abrupt disturbance in the geomagnetic field, which can cause an intense but brief disruption in HF propagation, but can cause an auroral event.

X-Ray: Hard X-Rays. Value from A0.0 to X9.9. Intensity of hard x-rays hitting the earth’s ionosphere. Impacts primarily the D-layer (HF absorption). The letter indicates the order of magnitude of the X-rays (A, B, C, M and X), where A is the lowest. The number further defines the level of radiation. The higher the value, the stronger the absorption.

304A: 304 Angstroms. Value from 0 to unknown. Relative strength of total solar radiation at a wavelength of 304 angstroms (or 30.4 nm), emitted primarily by ionized helium in the sun's photosphere. Correlates to SFI.

Pf: Proton Flux. Value from 0 to unknown. Density of protons in the solar wind. The higher the numbers (>1000), the more the impact the ionosphere. Primarily impacts the E-Layer of the ionosphere.

Ef: Electron Flux. Value from 0 to unknown. Density of electrons in the solar wind. The higher the numbers (>1000), the more the impact the ionosphere. Primarily impacts the E-Layer of the ionosphere.

Aurora: Indicates how strong the F-Layer ionization is in the polar regions. Higher values cause auroral events (including northern/southern lights) to move to lower latitude.

Bz: Bz Component. ACE Satellite reported value from +50 to -50. Strength and direction of the interplanetary magnetic field as impacted by solar activity. Positive is same direction as the earth's magnetic field, and negative is the opposite magnetic polarity. Cancels out earth’s magnetic field when negative, which increases the impact of solar particles in the ionosphere.

SW: Solar wind. ACE Satellite reported value from 0 to 1000. Speed (kilometers per second) of the charged particles as they pass earth. The higher the speed, the greater the pressure is exerted on the ionosphere. Values greater than 500 km/sec have impact on HF communications.

HF Conditions: Self explaining, "Good" to "Band closed". Useability of several HF bands.

VHF Conditions: Just the same for VHF bands with additional information regarding Aurora communication. Aur Lat: Calculated value from 67.5 to <45.0. Calculation from NOAA utilizes the current Aurora measurement. Used to estimate the lowest latitude impacted by the auroral event.  Aurora: DX-Robot reported event. Reports Band Closed for No/Low Auroral activity, High LAT AUR for Auroral activity >60°N, or MID LAT AUR for Auroral activity from 60° to 30°N.

EME Deg: Earth-Moon-Earth Degradation. Essential for moonbounce communication. Reports EME path attenuation as Very Poor (>5.5dB), Poor (4dB), Moderate (2.5dB), Good (1.5dB), Very Good (1dB), Excellent (<1dB).

Solar Flare Prb: Solar Flare Probability. Reports the probability (in %) of a solar flare within the next 24 hours (0-100%). Solar Flares are eruptions of electromagnetic radiation originating in the sun's atmosphere. A flare influences several values mentioned above.

MUF: Maximum Usable Frequency. Provides the Maximum Usable Frequency in a colored bar. Gray indicates No Sporadic E (ES) activity , blue indicates ES reported @ 6M, green indicates ES reported @ 4M, yellow indicates conditions support 2M ES, and red indicates reported @ 2M.

MS: Meteor Scatter Activity Bar. Provides the Meteor Scatter activity in a colored bar. Gray indicates no activity. See the color coded graph at the bottom of the bar for activity level.

Geomag Field: Geomagnetic Field. Calculated value. Indicates how quiet or active the earth's magnetic field is based on the K-Index value. Reports as Inactive, Very Quite, Quiet, Unsettled, Active, Minor Storm, Major Storm, Severe Storm, or Extreme Storm. Higher indications can cause HF blackouts and auroral events.

Sig Noise Lvl: Signal Noise Level. Calculated value. Indicates how much noise (in S-units) is being generated by interaction between the solar wind and the geomagnetic activity. A more active and disturbed solar wind, the greater the noise.

MUF US Boulder: MUF (see above). Provides the maximum usable frequency in MHz at one of 11 locations worldwide.

Current solar image: Photograph of the sun at a specific wavelength. Here: 30.4 nm; Helium 1 time ionized.