Solar Terrestrial Activity Report

Last update issued on August 31, 2003 at 04:10 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 minor storm on August 30. Solar wind speed ranged between 485 and 641 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 114.0. The planetary A index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 17.6).
Three hour interval K indices: 45333332 (planetary), 45333432 (Boulder).

The background x-ray flux is at the class B2-B3 level.

At midnight there were 7 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day.

Region 10442 added a few spots during the first half of the day, however, these spots were gone by midnight. Flare: C1.4 long duration event peaking at 05:14 UTC.
Region 10444 lost nearly all penumbral area while a few small spots emerged.
Region 10445 decayed and will likely become spotless today. Flare: C1.2 at 18:02 UTC.
Region 10447 decayed slowly and could become spotless today.
Region 10448 did not change significantly and remained quiet.
Region 10449 was quiet and unchanged.
Region 10450 was quiet and stable. Magnetograms suggest that regions 10449 and 10450 are one region with region 10449 containing the leading negative spots and region 10450 having the positive trailing spots.

Coronal mass ejections (CMEs)

August 28-30: 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 00:00 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 active until the first half of September 1. On September 1-5 a high speed stream from coronal hole CH54 will likely 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. 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). Several other frequencies had stations from Venezuela as well].

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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.

Solar region Date numbered SEC
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10441 2003.08.21 1   N15W80 0020 AXX spotless
10442 2003.08.22 2 1 S12W35 0080 CSO classification was HSX
at midnight
10444 2003.08.25 6 14 N09W33 0040 DSO  
10445 2003.08.25 4 5 N03W32 0040 DSO classification was BXO
at midnight, area 0010
10446 2003.08.27     S23W03     plage
10447 2003.08.28 2 2 N15W37 0010 HRX classification was AXX
at midnight
10448 2003.08.28 9 17 N20E06 0090 DSO classification was DAO
at midnight
10449 2003.08.28 4 4 S15E39 0130 DAO  
10450 2003.08.29 1 3 S18E52 0070 HSX probably the trailing
spots of region 10449
10451 2003.08.29     S10W78     plage
10452 2003.08.29 1   S06W05 0000 AXX spotless
S245 emerged on
2003.08.29
    N24W45     plage
S246 emerged on
2003.08.29
    N10W18     plage
Total spot count: 30 46
SSN: 120 116

Monthly solar cycle data

Month Average solar
flux at Earth
International sunspot number Smoothed sunspot number
2000.04 184.2 125.5 120.8
cycle 23 sunspot max.
2000.07 202.3 170.1 119.8
2001.12 235.1 132.2 114.6 (-0.9)
2002.07 173.5 99.6 102.7 (-3.5)
2002.08 183.6 116.4 98.7 (-4.0)
2002.09 175.8 109.6 94.6 (-4.1)
2002.10 167.0 97.5 90.5 (-4.1)
2002.11 168.7 95.5 85.2 (-5.3)
2002.12 157.2 80.8 82.0 (-3.2)
2003.01 144.0 79.7 81.0 (-1.0)
2003.02 124.5 46.0 (77.2 predicted, -3.8)
2003.03 131.4 61.1 (71.5 predicted, -5.7)
2003.04 126.4 60.0 (66.6 predicted, -4.9)
2003.05 115.7 55.2 (61.7 predicted, -4.9)
2003.06 129.3 77.4 (57.7 predicted, -4.0)
2003.07 127.7 85.0 (54.1 predicted, -3.6)
2003.08 122.5 (1) 111.0 (2) (52.3 predicted, -1.8)

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.


[DX-Listeners' Club]