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Geomagnetic activity in September 1991
Mean Ap20.5No. 140 of 1138
G1+ days10
G3+ days1
Max Ap5025 Sep 1991
Daily Ap
Daily max Kp
| Date | Max Kp | Ap | Level |
|---|---|---|---|
| 1 Sep 1991 | 6o | 47 | G2 |
| 2 Sep 1991 | 6- | 28 | G2 |
| 5 Sep 1991 | 5- | 21 | G1 |
| 8 Sep 1991 | 5o | 22 | G1 |
| 9 Sep 1991 | 7o | 49 | G3 |
| 10 Sep 1991 | 6+ | 37 | G2 |
| 25 Sep 1991 | 6+ | 50 | G2 |
| 26 Sep 1991 | 5o | 37 | G1 |
| 27 Sep 1991 | 6- | 48 | G2 |
| 28 Sep 1991 | 6- | 40 | G2 |
Same month a year earlier
| Month | Mean Ap | G1+ | G3+ |
|---|---|---|---|
| September 1990 | 13.6 | 6 | 1 |
| September 1991 | 20.5 | 10 | 1 |
Dates and time slots are UTC. Kp is the 3-hourly planetary geomagnetic index (0–9); Ap is the daily average disturbance. G1–G5 follow the NOAA storm scale (Kp 5- and above counted as G1). Aurora visibility also depends on weather and location. The latest values are preliminary.
About this page
Mean Ap 20.5 in September 1991, No. 140 of 1138 months since 1932; 10 days reached G1 or higher.