Solar Terrestrial Activity Report

Last major update issued on November 20, 2004 at 04:55 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 4, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 4, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update November 4, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update November 8, 2004)]
[Archived reports (last update November 12, 2004)]

Recent activity

The geomagnetic field was inactive to quiet on November 19. Solar wind speed ranged between 309 and 446 km/sec. A high speed stream from coronal hole CH127 arrived after noon. Initially the effects on the geomagnetic field were minor, however, late in the day the interplanetary magnetic field swung southwards and unsettled to active conditions are observed early on November 20.

Solar flux measured at 20h UTC on 2.8 GHz was 102.2. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.4).
Three hour interval K indices: 02001222 (planetary), 03102222 (Boulder).

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

At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 3 C class events was recorded during the day. All events occurred in region 10700 which has rotated over the northwest limb. Flares: C2.9 at 00:52, C3.4 at 02:20 and C4.9 at 05:12 UTC.

Spotted regions not numbered by NOAA/SEC:
[S480] This region rotated into view at the southeast limb on November 19. Only a single, small spot was observed at midnight.

Coronal mass ejections (CMEs)

November 17-19: No obviously Earth directed 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

Recurrent coronal hole CH127 in the northern hemisphere in a geoeffective position on November 15-18. Recurrent coronal hole CH128 in the southern hemisphere will likely rotate into a geoeffective position on November 21-23.

Processed SOHO/EIT 284 image at 01:06 UTC on November 20. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on November 20, quiet to active on November 21 and quiet to unsettled on November 22-23.

Coronal holes (1)	Coronal mass ejections (2)	M and X class flares (3)

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. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (with Union Radio Noticias programming). On other frequencies there was not much to hear, however, on the positive side, both WWZN Boston on 1510 and WDHP on 1620 kHz were back after a long absence.

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.

Monthly solar cycle data

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.