Solar Terrestrial Activity Report

Last update issued on October 17, 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 October 4, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update October 15, 2003)]
[Archived reports (last update October 15, 2003)]

Recent activity

The geomagnetic field was unsettled to minor storm on October 16. Solar wind speed ranged between 542 and 622 km/sec under the influence of a high speed stream from coronal hole CH63.

Solar flux measured at 20h UTC on 2.8 GHz was 95.2. The planetary A index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 27.4).
Three hour interval K indices: 53454444 (planetary), 53453334 (Boulder).

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

At midnight there were 2 spotted regions on the visible disk. Solar flare activity was very low.

Region 10477 simplified during the day and lost some trailing spots.
Region 10480 decayed slowly and quietly.

New regions are likely to rotate into view at the east limb over the next 2 days as there has been quite a bit of activity in recent SOHO/EIT images.

Coronal mass ejections (CMEs)

October 14-16: No potentially geoeffective CMEs observed. A halo CME on October 15 likely had a backside origin.

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 recurrent trans equatorial hole (CH63) will rotate into a geoeffective position on October 12-18. CH63 has become much smaller over the last rotation, losing most of its extension into the northern hemisphere. CH63 has merged with what was CH59 in the southeast.

Processed SOHO/EIT 284 image at 19:06 UTC on October 16. 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 17 and unsettled to active on October 18-21 (possibly with minor storm intervals on October 20 and 21) due to a high speed stream from coronal hole CH63.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very 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 Cristal del Uruguay and Radio Vibración (Venezuela)].

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
10477 2003.10.06 5 3 S14W63 0050 DRO classification was CSO
at midnight, area 0030
10479 2003.10.10     N24W19     plage
10480 2003.10.15 3 2 N20W40 0040 DRO classification was HSX
at midnight
S273 emerged on
2003.10.08
    N13W47     plage
S274 emerged on
2003.10.09
    N10W78     plage
Total spot count: 8 5
SSN: 28 25

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)
2002.09 175.8 109.6 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)
2003.10 109.5 (1) 35.4 (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]