3 Kp index 18 ap index
Weak Geomagnetic Storm
PLANETARY INDICES
Weak High Latitude Aurora Viewing Possible
Est. daily 13 Ap index
Weak Geomagnetic Storm
RADIO AURORA ACTIVE
High Latitude Weak Radio Aurora
50-144 MHz Possible
The higher the Kp index (0-9) the greater the chance of seeing the Aurora Borealis. The three-hourly K-index data are collected from ground-based magnetometers at 13 mid-latitude observatories. The scale is non-linear.
The ap index (0-400) is the equivalent three-hourly range: the amplitude on a linear scale.
This Ap index estimate is the rolling average of the last 8 ap indices: the actual Ap index is the average ap for the UT day. High Kp, ap & Ap indices (as a result of strong solar activity) may indicate enhanced VHF radio communication (28-433 MHz) at a range of 1000 miles or more in mid- to high latitudes: the radio-aurora.