Solar Terrestrial Activity Report

Last major update issued on November 16, 2006 at 04:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 12, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 12, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update November 12, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update November 12, 2006)]

Recent activity

The geomagnetic field was quiet on November 15. Solar wind speed ranged between 320 and 355 km/s (all day average 340 km/s - decreasing 19 km/s from the previous day). A disturbance arrived at ACE after 14h UTC. While the interplanetary magnetic field was moderately southwards most of the time after 18h UTC, it wasn't until early on November 16 that the interaction with the geomagnetic field became significant. Solar wind speed has remained at fairly low levels and didn't increase notably until 03h on Nov.16. Even after that time the speed has varied between 360 and 400 km/sec. The planetary K index was 5 for the first 3-hour interval on Nov.16. Interestingly the disturbance seems to have affected middle latitudes much more than high latitudes. Magnetometers in Alaska recorded magnetic fluctuations corresponding to a K index of 2 while stations further south reported K 4 or 5.

Solar flux measured at 20h UTC on 2.8 GHz was 96.1. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.8). Three hour interval K indices: 22011002 (planetary), 23111212 (Boulder).

The background x-ray flux is at the class A7 level.

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.

Region 10923 added a few small spots just northeast and southwest of the huge penumbra.
Region 10924 developed as new flux emerged in the central part of the region. The separation between the opposite polarity areas is poor in that part and further C class flares are possible. Flare: C1.8 at 19:01 UTC.
Region 10925 split off a small spot from the eastern part of main penumbra.

Coronal mass ejections (CMEs)

November 13-15: No obvious partly or fully Earth directed CMEs were detected in LASCO imagery.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent coronal hole, CH248, in the southern hemisphere will likely rotate into an Earth facing position on November 20-21. A weak coronal structure is just west of region  10923, this is perhaps the remains of CH244.

Processed SOHO/EIT 284 image at 19:06 UTC on November 14. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to minor storm on November 16 and quiet to unsettled on November 17-18.

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) Effects from a CME are likely to be observed at 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 poor to fair. Propagation on long distance northeast-southwest paths is poor.

Monitoring remarks from a location near N58E06: A  number of stations from North America were audible during the night, although rapid fade ins and outs occurred frequently. One minute I was listening to 1130 WBBR with an excellent signal, the next minute the station was gone only to reveal a much weaker signal from Radio Ideal (Venezuela). Propagation was best to the New York area and to the Canadian Atlantic provinces. Further south propagation to Colombia was good at 03h UTC, strong signals were noted on 650, 980, 1230 and 1340 (La Cariñosa, Bogotá).

Active solar regions (Recent map)

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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% lower.

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.