Solar Terrestrial Activity Report

Last update issued on October 2, 2003 at 03:55 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 1. Solar wind speed ranged between 276 and 326 km/sec. A disturbance arrived at ACE at approximately 16h UTC. At first the interplanetary magnetic field was weakly southwards, then became moderately to strongly southwards between 19 and 21h UTC. After 21h UTC the IMF has been northwards. At the current strength of the total field a sustained southward swing could cause at least minor storm conditions. Solar wind speed has only increased slightly since the arrival of the disturbance.

Solar flux measured at 20h UTC on 2.8 GHz was 136.8 The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 11.5).
Three hour interval K indices: 32232233 (planetary), 32222234 (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 moderate. A total of 6 C and 1 M class events was recorded during the day. A C1.4 flare at 07:20 and a C1.2 flare at 09:15 UTC was optically uncorrelated.

Region 10464 decayed slowly and will be rotating over the northwest limb today and tomorrow. Flares: C3.3 at 04:24, M1.4/1F at 04:51 and C1.6 at 17:52 UTC.
Region 10466 was quiet and stable.
Region 10470 developed early in the day, then decayed slowly. Flare: C1.6 long duration event peaking at 19:52 UTC.
Region 10471 developed slowly and was mostly quiet. The region has mixed polarities and could produce minor M class flares.
New region 10472 emerged in the southeast quadrant on September 29 and was numbered by SEC 2 days later.

Coronal mass ejections (CMEs)

September 29 - October 1: 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 mostly quiet to unsettled October 2-6, isolated active intervals are possible on October 2-3.

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. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). On 1510 kHz WWZN Boston had a strong signal].

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 16 14 N05W73 0480 FKI beta-gamma
classification was FAO
at midnight, area 0320
10465 2003.09.22     S02W71     plage
10466 2003.09.22 4 2 S04W50 0030 CSO  
10467 2003.09.23 3   S11W58
(SEC:
S05W51)
0030 DSO region is spotless,
SEC has duplicated
the data for region
10466!
10469 2003.09.27 1   S09W82 0040 HSX rotated out of view
10470 2003.09.29 7 7 S13E04 0030 DSO classification was CAO
at midnight
10471 2003.09.30 20 23 S08E53 0330 FSI beta-gamma
10472 2003.10.30 5 9 S23W02 0020 DSO formerly region S265
classification was DAO
at midnight, area 0050
S261 emerged on
2003.09.23
    S08W88     plage
S267 emerged on
2003.09.29
    S18E15     plage
S268 emerged on
2003.09.30
    N25W25     plage
Total spot count: 56 55
SSN: 126 105

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)
2002.08 183.6 116.4 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)
2003.10 136.8 (1) 4.1 (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]