Solar Terrestrial Activity Report

Last update November 25, 2001 at 03:40 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 1, 2001)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 1, 2001)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update November 1, 2001)]
[Historical solar and geomagnetic data charts 1954-2001 (last update October 16, 2001)]

Recent development

The geomagnetic field was unsettled to extremely severe storm on November 24. Solar wind speed ranged between 420 and 1002 km/sec. Two separate solar wind shocks were observed at SOHO, the first one at about 04:20 with an increase in solar wind speed from 460 to 590 km/sec (the source of this shock may have been a halo CME observed on Nov.21). The second and most significant shock was exceptionally strong at 05:33 UTC with solar wind speed increasing abruptly from 540 to 730 km/sec and later on increasing to 1000 km/sec (the source of this was mainly the halo CME observed after the M9 proton flare from region 9704 late on Nov.22, just above 30 hours in transit). Intense geomagnetic storming was observed, particularly during the 07-08h UTC interval when many magnetometers were subjected to K9 fluctuations. The major part of the geomagnetic storm was over by 16h UTC.

Solar flare activity was low. Solar flux was 173.0, the planetary A index was 108 (3-hour K indices: 3597 8734, Boulder K indices: 3596 7524). Region 9698 rotated quietly off the visible disk. Region 9704 still has magnetic delta structure, and, although slow decay is observed, could be the origin of another major proton flare before rotating off the visible disk late on Nov.26). Region 9710 decayed further and was quiet. Region 9712 was quiet and mostly stable. Region 9713 decayed quickly and was spotless by the end of the day. Region 9714 decayed and could soon become spotless. Region 9715 was mostly quiet and stable. A new region is rotating into view at the southeast limb. A region a few days behind the northeast limb has recently produced multiple CMEs and could be the next interesting region to watch. 

Flares and CMEs

A total of 10 C class events were recorded on November 24. Region 9704 produced a C3.7 flare at 00:19, a C1.4 flare at 01:53, a C7.5 flare at 05:53, a C2.4/1F flare at 15:13, a C5.2 flare at 17:15, a C7.1 flare at 17:58 and a C1.9 flare at 21:08 UTC.

The background x-ray flux is at the class C1 level.

Coronal holes

No obvious coronal holes are currently approaching geoeffective positions.

Forecast

The geomagnetic field is expected to be quiet to active with a possibility for minor storm intervals on November 25 and quiet to unsettled on November 26. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless.

Coronal holes (1)	Coronal mass ejections (2)	M and X class flares (3)

1) Effects from a coronal hole could reach earth within the next 5 days.
2) Material from a CME is likely to impact earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.

Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.

Active solar regions (Recent map)

Monthly solar data

1) Running average based on the daily 20:00 UT solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-40% less.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. Comments and suggestions are always welcome.