Solar Terrestrial Activity Report

Last update issued on July 6, 2003 at 04:00 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 unsettled to active on July 5. Solar wind speed ranged between 645 and 802 km/sec under the influence of a high speed stream from the eastern part of coronal hole CH46. A sudden increase in solar wind speed near 10:10 UTC at ACE and atypical (for a high speed stream) development of other solar wind data - including the total field of the interplanetary magnetic field - indicate the presence of a CME embedded within the coronal hole flow. The most likely origin would be a CME associated with the M3 flare in region 10397 on July 2.

Solar flux measured at 20h UTC on 2.8 GHz was 141.9. The planetary A index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 17.5).
Three hour interval K indices: 43433333 (planetary), 43434433 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was low. A total of 8 C class events was recorded during the day.

Region 10397 developed slowly. A new large penumbra formed in the leading part of the trailing spot section. There is still a magnetic delta structure within a northern penumbra in the trailing spots. The region has the potential to produce major flares, even an X class flare is possible. Flares: C1.0 at 03:31, C1.0 at 05:44, C1.1 at 05:53, C2.3 at 09:15, C2.5 at 12:45, C3.9 at 17:02 and a C4.4 long duration event peaking at 19:46 UTC.
Region 10398 was quiet and stable.
Region 10400 developed slowly in the trailing spot section with a magnetic delta forming in the northwestern part of the largest penumbra. Minor M class flares are possible. Flare: C1.7 at 23:35 UTC. The region was the source of an M2.3 flare at 00:32 UTC on July 6. GOES SXI images indicate that there was a CME associated with this event.

Coronal mass ejections (CMEs)

July 3-5: Only a few LASCO images available. 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.

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

Large extensions of the southern polar coronal hole (CH46) were in geoeffective positions from late on June 24 until July 2. A recurrent trans equatorial coronal hole (CH47) will be rotating into a geoeffective position on July 8-9.

Processed SXI coronal structure image at 20:44 UTC on July 5. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on July 6-7. A CME associated with an M2 flare in region 10400 early on July 6 could reach Earth on July 8 and cause unsettled to minor storm conditions that day and on  July 9. 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 very poor. Propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay.]

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.