Solar Terrestrial Activity Report

Last update issued on July 4, 2003 at 03:10 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 active on July 3. Solar wind speed ranged between 478 and 690 km/sec under the influence of a high speed stream from the eastern part of coronal hole CH46.

Solar flux measured at 20h UTC on 2.8 GHz was 132.2. The planetary A index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 17.9).
Three hour interval K indices: 33233444 (planetary), 33233434 (Boulder).

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

At midnight there were 5 spotted regions on the visible disk. Solar flare activity was low. A total of 6 C class events was recorded during the day

Region 10390 decayed slowly and quietly.
Region 10397 redeveloped a magnetic delta structure in a trailing penumbra. Several new small spots emerged. M class flaring is likely. Flares: C1.2 at 01:13 and C3.3 at 14:58 UTC.
Region 10398 decayed slowly and could soon become spotless.
Region 10399 decayed and could become spotless today.
Region 10400 developed moderately quickly. The spot distribution indicates that the region is actually two regions with the southern part slightly further west than the northern part. The positive and negative polarity spots in both sections are narrowly separated and a magnetic delta structure may have formed in the northern section. Flares: C3.8 at 06:02, C2.7 at 12:12, C2.8 at 12:36 and C1.6 at 21:07 UTC.

Coronal mass ejections (CMEs)

July 1-3: No LASCO images available on July 1. Some images from July 2 and 3 are 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.

July 2: An M3 flare in region 10397 may have been associated with a possibly geoeffective CME. If there was a CME it could reach Earth between noon on July 4 and July 5.

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) mainly were in geoeffective positions from late on June 24 until July 2.

Processed SOHO EIT  284 image at 17:59 UTC on July 3. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to active on July 4-6 with a possibility of occasional minor storm intervals due to a high speed stream from coronal hole CH46. Quiet to unsettled is expected for July 7-9.

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. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: none, several stations, including Radio Cristal del Uruguay, were observed with nearly equal signal strength.]

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.