Solar Terrestrial Activity Report

Last update issued on July 10, 2003 at 04:15 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 on July 9. Solar wind speed ranged between 379 and 485 km/sec. A weak solar wind disturbance was observed at ACE after 18h UTC. Between 18 and 19h UTC solar wind speed increased from 380 to 450 km/sec and solar wind density increased from 3 to 10 particles/cm3. While density has since stayed near 10 p/cm3, solar wind speed has decreased and is early on July 10 near 360 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 126.0. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 7.3).
Three hour interval K indices: 22122222 (planetary), 12211122 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight there were 7 spotted regions on the visible disk. Solar flare activity was moderate. A total of 13 C and 1 M class events was recorded during the day.

Region 10397 decayed quickly but warmed and produced lots of flares during the latter half of the day. The region will be rotating over the northwest limb today and tomorrow. Flares: C1.3 at 13:35, C5.8 (associated with a moderate type II radio sweep) at 16:37, C1.3 at 19:18, C1.8 at 19:30, C2.6 at 19:47, C2.5 at 20:27, C5.4 at 20:50 and M2.0 at 22:38 (there was a nearly simultaneous event in region 10400, however that event was not as intense) UTC.
Region 10400 decayed in the southern part of the trailing spot section and in the leading spot section. Some development was observed in the northern part of the trailing spots. Flares: C1.4 at 02:21, C1.3 at 05:07, C1.1 at 07:09, C3.5 at 11:25 and C2.3 at 15:25 UTC.
Region 10401 developed slowly and could produce further C class flares.
Region 10402 decayed significantly with the positive and negative polarity areas separating. The region will be rotating over the southwest limb today and tomorrow. Flare: C2.4 at 14:46 UTC.
Region 10403 decayed slowly and quietly.
Region 10404 decayed in the leading spot section and was quiet.

Spotted regions not numbered by SEC:
[S199] A new region emerged in the southwest quadrant on July 9. Location at midnight: S07W32.

Coronal mass ejections (CMEs)

July 7-9: A few LASCO images available on July 7, none on July 8-9. 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 8: A large filament eruption was observed late in the day north and northeast of region 10397 near 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) in the northern hemisphere will rotate into a geoeffective position on July 12-14.

Processed GOES SXI coronal structure image at 20:24 UTC on July 9. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on July 10. A high speed stream from coronal hole CH47 will likely cause unsettled to active conditions on July 11-13 while the high speed stream from coronal hole CH48 will cause unsettled to minor storm conditions on July 15-17.

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 fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: several stations noted early on, at local sunrise Radio Cristal del Uruguay was the best. Surprisingly on 1440 kHz a station from Uruguay was heard well above the usually very dominant Super AM 1440. After several months of absence VOCM 590 kHz was finally heard again. There were a few east coast US stations with fair signals 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.