Solar Terrestrial Activity Report

Last update issued on February 2, 2003 at 03:00 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update January 27, 2003)]
[Archived reports (last update January 27, 2003)]

Recent activity

The geomagnetic field was quiet to minor storm on February 1. Solar wind speed ranged between 338 and 971 km/sec. An unusual solar storm arrived at SOHO near 13:10 UTC. This storm is unusual in that solar wind speed was very low at the time of its arrival and had some of the highest peak solar wind speeds recorded during this solar cycle. At the first solar wind shock the velocity jumped abruptly from 390 to 520 km/sec, then increased slowly to 600 km/sec. Near 14:30 UTC at SOHO there was another shock, this time speed increased to above 800 km/sec. By 16h UTC solar wind speed had peaked just below 1000 km/sec. The interplanetary magnetic field was mostly northwards for the remainder of the day. Early on February 2 solar wind speed has decreased to below 600 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 125.8. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.8).
Three hour interval K indices: 32122254 (planetary), 22222343 (Boulder).

The background x-ray flux is at the class B6 level.

At midnight there were 5 spotted regions on the visible disk, 1 of which has not yet been numbered by SEC/NOAA. Solar flare activity was moderate. A total of 7 C and 1 M class flares were recorded during the day.

Region 10269 decayed slowly and quietly.
Region 10272 was quiet and mostly unchanged.
Region 10274 was quiet and stable.
New region 10276 rotated partly into view at the southeast limb. This region is very active and may be capable of producing further M class flares. Flares: C1.5 at 00:19, C2.6 at 06:13, M1.2 long duration event peaking at 09:05, C2.7 at 11:41, C1.4 at 12:03, C1.3 at 17:15, C1.0 at 19:08 and C9.9 at 19:54 UTC.

Spotted regions not yet numbered by SEC/NOAA:
[S85] A new region emerged in the southwest quadrant. Location at midnight: S13W22.

Coronal mass ejections (CMEs)

January 31-February 1: No obviously geoeffective CMEs observed.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A large and well defined trans equatorial extension of the northern polar coronal hole will rotate into a geoeffective position on February 1-3.

Processed SOHO EIT 284 image at 19:06 UTC on January 31. [Due to a CCD bakeout the next image will likely be produced on February 4.] Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to major storm on February 2 and quiet to active on February 3. A possibly strong coronal stream will likely begin to influence the geomagnetic field on February 4 and could cause unsettled to minor storm conditions until February 6 or 7. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor, propagation along north-south paths is fair to good.

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)

Compare to the previous day's image.

Data for all numbered solar regions according to the Solar Region Summary provided by SEC/NOAA. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots.

Monthly solar cycle data

1) Running average based on the daily 20:00 UT observed 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 25-45% 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. All time references are to the UTC day. Comments and suggestions are always welcome.