Solar Terrestrial Activity Report

Last major update issued on January 3, 2005 at 03:40 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 2, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 2, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 2, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update November 8, 2004)]
[Archived reports (last update January 2, 2005)]

Recent activity

The geomagnetic field was unsettled to minor storm on January 2. Solar wind speed ranged between 539 and 975 km/sec. An unusually high speed stream from coronal hole CH136 arrived at SOHO just after 02h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 100.0. The planetary A index was 33 (STAR Ap - based on the mean of three hour interval ap indices: 33.3).
Three hour interval K indices: 44543535 (planetary), 44533535 (Boulder).

The background x-ray flux is at the class B1-B2 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 1 C and class event was recorded during the day.

Region 10715 decayed significantly in the northeastern part. There is still little separation between the positive and negative polarity areas near the southeastern edge of the main penumbra. An M class flare is possible.  Flare: C1.2 at 13:06 UTC.
Region 10716 developed slowly and added a few small spots.

Coronal mass ejections (CMEs)

January 1: A large and partially Earth directed CME is likely to have been associated with the X1.7 event early in the day and could reach Earth during the first half of January 3.
December 31 and January 2
: No obviously Earth directed CMEs were 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

Recurrent large trans equatorial coronal hole CH136 was in a geoeffective position on December 31-January 2.

Processed SOHO/EIT 284 image at 01:06 UTC on January 3. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to minor storm on January 3-5 due to a CME and coronal hole effects.

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. When the high speed stream has arrived the color changes to green.
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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor to poor. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay (presumed). On other frequencies propagation was best towards Brazil. Only two stations from North America were noted: CBA Moncton on 1070 and WWZN Boston on 1510 kHz.

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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.

Active region Date numbered SEC
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10715 2004.12.28 17 16 N05E08 0130 DSI beta-gamma
classification was DAI
at midnight
10716 2004.12.30 2 6 S13E11 0010 CSO classification was BXO
at midnight, area 0020
10717 2004.12.31 3   N08W86 0110 DSO rotated out of view
S491 emerged on
2004.12.26
    S16W76     plage
Total spot count: 22 22
SSN: 52 42

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)
2003.11 140.8 67.3 56.7 (-1.5)
2003.12 114.9 46.5 54.8 (-1.9)
2004.01 114.1 37.3 52.0 (-2.8)
2004.02 107.0 45.8 49.3 (-2.7)
2004.03 112.0 49.1 47.1 (-2.2)
2004.04 101.2 39.3 45.5 (-1.6)
2004.05 99.8 41.5 43.9 (-1.6)
2004.06 97.4 43.2 41.7 (-2.2)
2004.07 119.1 51.0 (39.6 predicted, -1.9)
2004.08 109.6 40.9 (38.0 predicted, -1.6)
2004.09 103.1 27.7 (36.1 predicted, -1.9)
2004.10 105.9 48.4 (33.9 predicted, -2.2)
2004.11 113.2 43.7 (32.0 predicted, -1.9)
2004.12 94.5 17.9 (29.7 predicted, -2.3)
2005.01 99.5 (1) 3.3 (2) (27.0 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 some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.


[DX-Listeners' Club]