Solar Terrestrial Activity Report

Last update issued on September 1, 2003 at 03:30 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 unsettled on August 31. Solar wind speed ranged between 374 and 511 km/sec, slowly decreasing all day.

Solar flux measured at 20h UTC on 2.8 GHz was 109.7. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 8.8).
Three hour interval K indices: 22223222 (planetary), 23223222 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight there were 7 spotted regions on the visible disk. Solar flare activity was low. A total of 1 C class event was recorded during the day.

Region 10442 was mostly unchanged. Flare: C1.3 long duration event peaking at 06:22 UTC.
Region 10444 decayed and had only a few small spots left at midnight.
Region 10448 decayed slowly in the leader spots.
Region 10449 was quiet and unchanged. I have merged this region with region 10450 based on magnetogram and spot distribution analysis.

Spotted regions not numbered by NOAA/SEC:
[S245] This region first emerged on August 29, then became spotless. New spots emerged on August 31. Location at midnight: N23W61.
[S247] A new region emerged on August 31 in the southwest quadrant. Location at midnight: S10W28.
[S248] A new region emerged on August 31 in the southeast quadrant. Location at midnight: S23E35.

Coronal mass ejections (CMEs)

August 29-31: No potentially geoeffective CMEs observed.

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 large recurrent coronal hole (CH54) in the northern hemisphere and with a trans equatorial extension, will rotate into a geoeffective position on August 29- September 2.

Processed GOES SXI coronal structure image at 23:57 UTC on August 31. 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 early on September 1. Then a high speed stream from coronal hole CH54 will dominate the solar wind until September 5 and cause unsettled to minor storm conditions.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation along north-south paths is poor to fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela). A few North American stations were noted on frequencies above 1400 kHz].

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.