• Most Recent KP Index: Condition GREEN

This index is based on the most recent USAF/NOAA estimated planetary geomagnetic activity (KP) 3-hour index. Our index is determined as follows:
Condition Estimated (3-Hour) K_P
Green K_P < 4
Yellow 4 <= K <SUB />P < 7
Red K_P > = 7

• Solar Wind Observations: Condition GREEN

This index is keyed to the estimated instantaneous asymptotic voltage across the polar cap, the single most important measure of electrical power delivered to the atmosphere from the solar wind. We now use data from the ACE Real-Time Solar Wind package since this spacecraft is tracked more often than WIND. (The old estimate was based on observations from NASA's WIND spacecraft.) The index is determined as follows:
Condition Polar Cap Potential (PCP) Range
Green 0 kV <= PCP < 110 kV<BR />Yellow 110 kV <= PCP < 200 kV<BR />Red PCP > = 200 kV*

* The PCP status is changed to red only if the current 10-minute average exceeds 200 kV AND the previous 10-minute average exceeds 150 kV. This is designed to reduce shifts in status due to short-term spikes in the value of the potential.

• NOAA/SEC Forecast: Condition GREEN

This index is based on the forecasted geomagnetic event probabilities over the next two days (section VI of the NOAA/SEC Forecast) as follows:
Condition Next Day Probabilites (P₁) Second Day Probabilities (P₂)
Green P₁ <= 35% P <SUB />2 <= 35% <BR />Yellow 35% < P₁ < 50% P₂ > 35%
Red P₁ > = 50% Not Applicable

• Latest Observations from the ACE spacecraft