Solar Terrestrial Activity Report

Last update issued on August 28, 2003 at 03:50 UTC. 

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update August 18, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update August 18, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update August 18, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update July 23, 2003)]
[Archived reports (last update August 28, 2003)]

Recent activity

The geomagnetic field was quiet to active on August 27. Solar wind speed ranged between 418 and 532 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 125.7. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 14.1).
Three hour interval K indices: 22343333 (planetary), 22343433 (Boulder).

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

At midnight there were 9 spotted regions on the visible disk. Solar flare activity was low. A total of 5 C class events was recorded during the day. Region 10440 near the southeast limb produced a C1.6 flare at 02:50 UTC.

Region 10436 decayed further and could become spotless today. Flare: C1.9 at 05:08  UTC.
Region 10441 decayed slowly and quietly.
Region 10442 decayed in the leading spot section.
Region 10444 developed slowly and quietly.
Region 10445 decayed slowly. Flare: C1.3 at 09:05 UTC.
New region 10446 emerged in the southeast quadrant on August 26 and was numbered the next day by SEC.

Spotted regions not numbered by NOAA/SEC:
[S239] A new region emerged in the northeast quadrant on August 26. The region developed slowly on August 27. Location at midnight: N19E44.
[S240] This region emerged on August 27 to the north of region 10444. Location at midnight: N16E06.
[S241] A new region is rotating into view at the southeast limb and could produce at least C class flares. Location at midnight: S16E80. Flares: C1.2 at 16:32 and C1.1 at 22:45 UTC.

Coronal mass ejections (CMEs)

August 25-27: No potentially geoeffective CMEs observed. A filament eruption near region 10442 between 15 and 18h UTC on August 27 may have been associated with a CME.

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 coronal hole (CH53) in the southern hemisphere may have been in a geoeffective position on August 25. A coronal hole (CH54) in the northern hemisphere could reach a geoeffective position on August 30.

Processed GOES SXI coronal structure image at 00:00 UTC on August 28. Base SXI image courtesy of NOAA/SEC. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled until September 1. There is a chance of some geomagnetic effects from the northernmost extension of coronal hole CH53 on August 28-29.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. 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).]

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 analysis, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.