Solar Terrestrial Activity Report

Last update issued on October 3, 2003 at 03:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update September 1, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update September 1, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update September 1, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update July 23, 2003)]
[Archived reports (last update September 29, 2003)]

Recent activity

The geomagnetic field was quiet to unsettled on October 2. Solar wind speed ranged between 275 and 537 km/sec. The unusual disturbance which began on October 1 continued on October 2. The interplanetary magnetic field was northwards until about 20h UTC after which time increasingly more frequent and stronger southwards excursions have been observed.

Solar flux measured at 20h UTC on 2.8 GHz was 124.8. The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 10.0).
Three hour interval K indices: 23222333 (planetary), 23113213 (Boulder).

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

At midnight there were 5 spotted regions on the visible disk. Solar flare activity was low. A total of 4 C class events was recorded during the day. A C2.2 flare at 13:56 UTC was optically uncorrelated.

Region 10464 rotated partly out of view at the northwest limb. Flares: C2.4 at 04:01 and C7.8/1F at 06:56 UTC.
Region 10466 decayed slowly and quietly. The region could become spotless before rotating over the southwest limb on October 4.
Region 10471 developed moderately quickly in the trailing spot section where polarities are intermixed. A minor M class flare is possible. Flare: C4.2 at 16:11 UTC.
Region 10472 developed further with new intermediate spots emerging.

Spotted regions not numbered by NOAA/SEC:
[S269] A new region emerged in the northeast quadrant on October 2. Location at midnight: N10E03.

Coronal mass ejections (CMEs)

September 30 - October 2: 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

No obvious coronal holes are currently approaching geoeffective positions.

Processed SOHO/EIT 284 image at 19:06 UTC on September 25. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on October 3 and quiet to unsettled October 4-6.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is fair. Propagation along north-south paths is fair to good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) with a strong signal. Signals from both medium (European) and long distance (trans Atlantic) stations are elevated about 15 dB above normal. The current solar wind disturbance seems to have energized the propagation layers].

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
10464 2003.09.20 1 1 N05W81 0230 HHX classification was HSX
at midnight, area 0180
10465 2003.09.22     S02W84     plage
10466 2003.09.22 1 1 S05W64 0020 HSX  
10467 2003.09.23     S11W71
(SEC:
S05W64)
     
10470 2003.09.29 2   S14W08 0020 HSX spotless
10471 2003.09.30 16 22 S08E42 0520 FKO beta-gamma
10472 2003.10.30 5 10 S22W16 0040 DSO classification was DAO
at midnight, area 0060
S267 emerged on
2003.09.29
    S18E02     plage
S268 emerged on
2003.09.30
    N25W38     plage
S269 emerged on
2003.10.02
  3 N10E03 0020 CRO  
Total spot count: 25 37
SSN: 75 87

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)
2002.08 183.6 116.4 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 80.9 (-1.1)
2003.02 124.5 46.0 78.5 (-2.4)
2003.03 131.4 61.1 74.1 (-4.4)
2003.04 126.4 60.0 (69.6 predicted, -4.5)
2003.05 115.7 55.2 (65.3 predicted, -4.3)
2003.06 129.3 77.4 (61.5 predicted, -3.8)
2003.07 127.7 85.0 (58.0 predicted, -3.5)
2003.08 122.1 72.7 (55.0 predicted, -3.0)
2003.09 112.2 48.8 (53.0 predicted, -2.0)
2003.10 130.8 (1) 6.5 (2) (50.3 predicted, -2.7)

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]