Solar Terrestrial Activity Report

Last major update issued on November 7, 2004 at 07:50 UTC. Last minor update posted at 16:28 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 August 28, 2004)]
[Archived reports (last update November 4, 2004)]

Recent activity

The geomagnetic field was inactive to quiet on November 6. Solar wind speed ranged between 312 and 350 km/sec. A weak solar wind shock was observed at SOHO at 02:22 on November 7. Solar wind speed increased abruptly from 315 to 355 km/sec. After a brief initial southward swing of the interplanetary magnetic field, the IMF has been mostly northwards resulting in only a mild increase in geomagnetic activity. This was likely the arrival of the CME observed after the M1 event in region 10696 on November 3.

Solar flux measured at 20h UTC on 2.8 GHz was 128.8. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.6).
Three hour interval K indices: 00001111 (planetary), 00001210 (Boulder).

The background x-ray flux is at the class B6 level.

At midnight there were 6 spotted regions on the visible solar disk. The solar flare activity level was high. A total of 6 C and 4 M class events was recorded during the day.

Spotted regions not numbered by NOAA/SEC:
[S470] This region emerged in the northeast quadrant on November 6. Location at midnight: N05E24.

Comment added at 10:17 UTC on November 7, 2004: A moderately strong solar wind shock was observed at ACE at 10:02 UTC with a sudden increase in solar wind speed from 340 to 420 km/sec. The interplanetary magnetic field initially swung strongly southwards. This was likely the arrival of the second halo CME observed on November 3. Further CME impacts are expected later today.

Comment added at 16:28 UTC: Region 10696 produced a major X2.0 flare at 16:06 UTC. It is likely that this event was associated with a larger and faster CME than those previously seen from this region. Expect major to very severe geomagnetic storming when this CME reaches Earth on November 9. The geomagnetic activity associated with the CME which arrived before noon today has intensified a lot over the last couple of hours with activity currently ranging from active to major storm.

Coronal mass ejections (CMEs)

November 6: A fast and large CME aimed almost directly at Earth was observed early in the day following a sequence of M class events in region 10696, the largest was an M9 event just after midnight. This CME could reach Earth during the latter half of November 7 or early on November 8. (Note that LASCO images are generally very poor in a sector covering the south pole, otherwise image quality is fairly good)
November 5: No obviously Earth directed CMEs observed.
November 4: Two full halo CMEs was observed during the day. The first one was after a long duration C6 event in region 10696 in the morning. This CME, if not overtaken by the larger CME observed later in the day, is likely to reach Earth on November 7. The second CME was associated with a major long duration event in region 10696 late in the day. This was a large full halo CME, and it is likely to reach Earth on November 7.
November 3: A halo CME was observed after an M1 event in region 10696 early in the day. While this CME was not aimed directly at Earth, a sideways glancing impact is possible late on November 6. A large full halo CME was observed after an M5 event in region 10696 during the afternoon. Again, this CME was not aimed directly at Earth. However, much more mass was observed over the west limbs compared to the event earlier in the day.

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

An extension (CH123) of the northern polar coronal hole was in a geoeffective position on November 3. A recurrent coronal hole (CH124) in the southern hemisphere was in a geoeffective position on November 4-5. Most of CH124 closed on November 5 due to the development of region 10696. Coronal hole CH125 in the southern hemisphere will likely rotate into a geoeffective position on November 8.

Processed SOHO/EIT 284 image at 19:06 UTC on November 6. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to major storm on November 7 due to several CME impacts. Minor to severe storming is possible late on November 7 or on November 8 when the largest CME arrives, the one observed after the M class events early on November 6. While two coronal hole streams are headed for Earth, none of them are likely to be noticed in the presence of the much more powerful CMEs.

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 was fair to good late on November 6 and early on November 7. Propagation has become noticeably poorer over the last several hours. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: WLAM Lewiston ME and Radio Vibración (Venezuela). Stations from the easternmost parts of North America were noted on quite a few other frequencies. At 21:30 UTC on November 6 the daytimers WFIF Milford CT on 1500 and WIZZ Greenfield MA on 1520 kHz were heard again. During local sunrise on November 7 propagation was best towards Florida (and Cuba) with WIOD Miami on 610 and WFTL West Palm Beach on 850 both having unusually good signals.

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.