Solar Terrestrial Activity Report

Last major update issued on October 29, 2010 at 03:50 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update October 2, 2010)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update October 2, 2010)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update October 2, 2010)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports from January 2003 (last update October 9, 2010)]

NEW [POES auroral activity level charts since October 2009]

The geomagnetic field was very quiet on October 28. Solar wind speed ranged between 379 and 471 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 86.4 (down 0.3 over the last solar rotation). The planetary A index  was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.9). Three hour interval K indices: 00001111 (planetary), 10112210 (Boulder).

The background x-ray flux is at the class A9 level.

At midnight UTC the visible solar disk had 2 spotted regions.

Region 11117 is becoming quite interesting as the main trailing spot is moving closer to the huge leader spot. Their longitudinal separation has decreased significantly over the last day and they could merge today if this development continues. In that case major flares will become possible.

Spotted regions not numbered by NOAA/SWPC:
[S830] This region emerged at a high latitude late in the day in the northwest quadrant on October 28. Location at midnight: N36W14

October 27-28: No obviously Earth directed CMEs were seen in LASCO or STEREO images.
October 26: A CME was observed starting at about 09h UTC following activity near region 11115. Although the CME will probably not reach Earth, there's a chance of a glancing blow.

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

No obvious coronal holes are currently in or near Earth facing positions. An extension of the southern polar coronal hole rotated across the central meridian on October 27-28 but is likely too far to the south to cause a disturbance. Another coronal hole in the northern hemisphere could rotate into an Earth facing position on October 30 but could be too far to the north to become geoeffective.

Image courtesy of SDO (NASA) and the AIA consortium. Annotations are my own. The darkest areas on the solar disk are likely coronal holes.

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is good. Propagation on long distance northeast-southwest paths is poor to fair.

The geomagnetic field is expected to be quiet on October 29-31. On October 29-30 there's a chance of unsettled intervals should the CME observed on October 26 reach Earth.

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.

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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.

Active region	Date numbered	Spot count		Location at midnight	Area	Classification		SDO (NASA) / AIA 4500 image		Comment
		SWPC	STAR			SWPC	STAR	Current	Previous
11118	2010.10.19			N14W44						plage
11117	2010.10.19	17	21	N22W41	0520	DKC	DKC
11119	2010.10.19			N24W73						plage
S829	2010.10.27			S20W58
S830	2010.10.28		3	N36W14	0020		CRO			plage
Total spot count:		17	24
SSN:		27	44

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the daily SWPC ap indices. Values in red are based on the official NGDC ap indices.

This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.