Solar Terrestrial Activity Report

Last update issued on July 9, 2003 at 04:10 UTC. 

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

Recent activity

The geomagnetic field was quiet to unsettled on July 8. Solar wind speed ranged between 439 and 545 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 131.3. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 7.0).
Three hour interval K indices: 11112232 (planetary), 21122211 (Boulder).

The background x-ray flux is at the class B5 level.

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was low. A total of 10 C class events was recorded during the day.

Region 10397 decayed significantly in the southern part of the trailing spot section. An M class flare is still a possibility. Flares: C2.1 at 01:03, C2.3 at 02:30, C2.0 at 04:08, C1.3 at 12:21 and C2.9 at 23:50 UTC.
Region 10400 lost some of the the easternmost trailing spots while slow development was observed in the leading spot section. The magnetic delta structure in the large asymmetrical penumbra became stronger and the chance of an M class flare is increasing. Flares: C1.5 at 02:51, C1.0 at 21:35 and C1.1 at 22:53 UTC.
Region 10401 developed penumbra on both polarities and was quiet.
Region 10402 developed quickly. There is very little separation between the positive polarity spots in the northeast and the easternmost negative polarity spots. Further development could cause a delta structure to form. The region may be capable of producing a minor M class flare. Flares: C5.2/1F at 07:30 and C3.2 at 16:26 (a simultaneous and equal intensity flare occurred at the same time in region 10400) UTC.
Region 10403 was quiet and stable.
Region 10404 developed slowly in the southeastern part and was quiet.

Coronal mass ejections (CMEs)

July 6-8: Some LASCO images available on July 6 and 7, none on July 8. There is a problem with the SOHO high gain antenna. Until the high gain antenna is in a favorable position starting from mid July, SOHO science data will be transmitted over a low gain antenna and only a limited amount of data will be available.

July 6: A fairly large filament eruption was observed beginning at 03:00 UTC in region 10397 and stretching east northeastwards across the central meridian. The CME associated with this event could be geoeffective and reach Earth on July 9.

July 8: A large filament eruption was observed late in the day north and northeast of region 10397 at the northwest limb. The associated CME is not likely to be geoeffective.

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 recurrent trans equatorial coronal hole (CH47) was in a geoeffective position on July 8-9. Another coronal hole (CH48) mainly in the northern hemisphere but with a trans equatorial extension, will rotate into a geoeffective position on July 13-14.

Processed GOES SXI coronal structure image at 17:25 UTC on July 8. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on July 9-10. There is a minor chance that a CME associated with a filament eruption early on July 6 could reach Earth on July 9 and cause unsettled to active conditions. A high speed stream from coronal hole CH47 will cause unsettled to active conditions on July 11-13.

Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation along north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) with Radio Cristal del Uruguay noted occasionally. Good signals noted from Venezuela on 1500 and 1520 kHz as well.]

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 NOAA/SEC. 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 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% 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.