Calculations

✅ How does the calculation for Aurora Seeing Chance (ASC) actually work?:

 

Aurora Seeing Chance (ASC) = Drivers × Visibility × Quality

Drivers:

Ovation, Hemispheric Power, Newell Coupling, Ground Magnetometers

Visibility:

Darkness Factor, Moon Illumination, Moon Position, Moon Phase, Cloud Cover

Quality:

How stale is the data? Are all input consist?

 

Once we have all of the inputs, we then add a weight specific to their portion of the 100% in the calculation e.g.

Driver Weights:

1. Ovation: 38.9% – For Ovation, we use your longitude and latitude coordinates to check them against NOAA ovation profiles to see if you are within the predicted zone. 
2. HPI: 22.2% – Hemispheric power is measured to see if it is contributing to seeing conditions.
3. Newell Coupling: 22.2% – Newell coupling measures solar wind and magnetosphere values at L1 and is a space weather predictor.
4. Ground Mag: 16.7% – Ground Mag then confirms the magnetic disturbance. As the Newell level is dropping energy may still be decaying at ground level. 

All of the above totals 100% for drivers.

 

Visibility:

1. For visibility we first check the Moon to see is it above the horizon. If it is, how much is it illuminated and where is it in the sky. We then check what phase it is in then give it a score 60 – 100% (60% being the worst).
2. Next we check if its Dark, this value will ramp as the Sun drops below the horizon from 0 – 100%. When it is at 0% (Daylight) the ASC calculation will read 0.0%
3. We then check for cloud cover 20- 100%. If its clouded over the calculation will read 20%, if the sky is clear it will read 100%

 

Then similar to an operational efficiency calculation we multiply them out to check the efficiency of all Aurora based inputs. Aurora Seeing Chance (ASC) = Drivers × Visibility × Quality

 

Additional Explanations:

✅ What is OVATION:

• OVATION Prime is NOAA/SWPC’s auroral oval model.
• It ingests solar wind + IMF (from L1) and outputs a global grid of auroral activity for N/S hemispheres, updated roughly every ~5 min.
• The grid cell values are essentially a probability/likelihood field for auroral precipitation (i.e., how likely the oval is over that spot).

How we use it:

1. Sample at your location: we take the OVATION JSON grid and read the cell(s) at your latitude/longitude .
2. Convert to a driver score: that local probability is transformed into OV Score (0–100) via a calibrated curve (low probabilities compress near 0, strong oval proximity ramps the score quickly).
3. Visibility is separate: Darkness/Moon/Clouds are not in OVATION; we apply them later as a multiplier: Aurora Seeing Chance = Drivers × Visibility × Quality

Why OVATION matters

• It’s the spatial “where” signal: it tells us if the oval actually reaches your latitude/longitude right now.
• HPI/Newell/Ground say “how strong the system is,” but OVATION pins that strength to your sky.

✅ What Newell Coupling Measures

The Newell coupling function is a proxy for solar wind–magnetosphere coupling.
It uses upstream conditions at L1:

✅ Solar wind speed (V)
✅ IMF magnetic field components (B, clock angle)
✅ Dayside reconnection rate

In other words: How strongly the solar wind is pumping energy into Earth’s magnetic system right now.

It predicts how much energy is entering the system — but NOT how the ionosphere or ground is responding yet.

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✅ What Ground Disturbance (Dst or ΔH) Measures

Ground indices (like Dst or local magnetometer ΔH) measure the RESULT of energy having already entered the system.

✅ Ring current strength
✅ Storm-time disturbance
✅ Ongoing geomagnetic activity observed at Earth’s surface

In other words: How much the magnetosphere is already shaken up.

It tells us if the system is currently disturbed — actual geomagnetic response, not just potential.

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So why use both?

You can have high Newell but low ground disturbance
(e.g., energy just started entering, ring current hasn’t built yet).

You can have low Newell but moderate ground disturbance
(e.g., energy entered in the past hours and is still decaying).

Using both gives a time-aware picture:

✅ Is energy being added now? (Newell)
✅ Has the system already reacted? (Ground)
✅ Combined → Is the system primed AND currently active?

✅ What is Darkness Factor?

It is a value from 0% to 100% that tells us how dark the sky currently is at your location — specifically with respect to twilight.

Aurora is only visible when the sky is dark enough. The Darkness Factor quantifies that.

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✅How is it calculated?

We use the Sun’s altitude (angle above/below the horizon) at your exact latitude/longitude right now.