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)
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
10442 2003.08.22 2 2 S13W47 0070 CSO classification was HSX
at midnight
10444 2003.08.25 10 1 N08W47 0050 CSO classification was AXX
at midnight, area 0010
10445 2003.08.25 4   N03W45 0030 CSO spotless
10446 2003.08.27     S23W16     plage
10447 2003.08.28 1   N14W50 0010 AXX spotless
10448 2003.08.28 10 15 N20W07 0070 DAO  
10449 2003.08.28 3 11 S17E33
(SEC:
S16E27)
0120 DAO merged with 10450
classification was EAO
at midnight
10450 2003.08.29 1   S18E39 0040 HSX see comment for
region 10449
10452 2003.08.29     S06W18     plage
S245 emerged on
2003.08.29
  3 N23W61 0010 BXO  
S246 emerged on
2003.08.29
    N10W31     plage
S247 emerged on
2003.08.31
  2 S10W28 0010 AXX  
S248 emerged on
2003.08.31
  1 S23W35 0010 AXX  
Total spot count: 31 35
SSN: 101 105

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)
2003.08 122.1 (1) 114.3 (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]