Solar Terrestrial Activity Report

Last major update issued on November 1, 2011 at 05:35 UTC. Minor update posted at 16:20 UTC

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update November 1, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update November 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update November 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update October 1, 2011)]

[POES auroral activity level since October 2009 - updated October 31, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2114 [August-September 2011] - 2115 [September-October 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on October 31. Solar wind speed ranged between 346 and 443 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 138.1 (increasing 7.6 over the last solar rotation). The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.8). Three hour interval K indices: 30112133 (planetary), 31112223 (Boulder).

The background x-ray flux is at the class C1 level.

At midnight UTC the visible solar disk had 9 spotted regions (in 2K resolution SDO images).

Region 11330 [N06W53] decayed slowly. The region still exhibits minor polarity intermixing and could produce an M class flare. Flares C2.3 at 01:10 UTC.
Region 11332 [N32W11] was quiet and stable.
Region 11333 [N16W41] decayed and could soon become spotless.
Region 11334 [N13E12] decayed slowly and could still produce occasional C class flares. Flares: C2.7 at 05:21 UTC.
New region 11335 [N18E17] emerged in the northeast quadrant on October 28, was spotless on Oct. 29 and reemerged on Oct. 30. The region was numbered by SWPC on Oct.31.
New region 11336 [N13E55] rotated into view at the northeast limb on October 29 and was numbered by SWPC 2 days later. The region has polarity intermixing and has developed quickly early on November 1. If this rate of development continues the region will soon become capable of producing M flares.
New region 11337 [N17E66] rotated into view at the northeast limb on October 30 and got an SWPC number the next day.

Spotted regions not reported by NOAA/SWPC:
[S1303] rotated into view at the southeast limb on October 31. Location at midnight: S13E86
[S1304] emerged in the northeast quadrant on October 31. Location at midnight: N20E06

A very active region at the northeast limb has become partly visible early on November 1. The region produced an M1.1 flare at 15:08, a C7.5 flare at 17:37, an M1.4 long duration event peaking at 18:08 and a C5.2 flare at 23:22 UTC.

Minor update added at 16:20 UTC on November 1, 2011: Region S1305 has rotated partially into view at the northeast limb displaying a large penumbra. Region 11336, which was developing quickly early in the day, has seen growth stagnation. The latest high resolution CHARMAP.

A solar wind shock was observed at 08:20 UTC at SOHO. The likely source was a CME observed early on October 29 following a filament eruption which began late on Oct.28 to the north of region 11330, then near the center of the visible disk. Unsettled to minor storm conditions have been observed since the arrival of the CME.

The international sunspot number for October 2011 was 88. Solar cycle 24 resembles cycle 10, another late starter, and could reach a peak near 100 (smoothed sunspot number) instead of 70 which has been predicted for the last 6 months.

Coronal mass ejections (CMEs)

October 29-31: No obviously Earth directed CMEs observed.

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 small coronal hole (CH482) in the northern hemisphere will be in an Earth facing position on October 31-November 1. CH482 became smaller on October 30 due to the development of region 11334. The filament eruption in the northeast quadrant opened up a new coronal hole. Normally the coronal holes left by filament eruptions close quickly, however, this one hasn't and will be numbered later today if it doesn't close. A small coronal hole (CH483) in the southern hemisphere will rotate into an Earth facing position on November 1.

The above coronal hole map is based on a new method where coronal holes are detected automatically. The method may need some fine tuning, however, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using the new method, the extent and intensity of both holes are consistent with other data sources.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet to active on November 1, quiet on November 2 and quiet to unsettled on November 3-4 due to weak coronal hole effects.

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

(Click on image for higher resolution image) Compare to the previous day's image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.

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 detected	Spot count		Location at midnight	Area	Classification		SDO / HMI 4K continuum image with polarity overlay		Comment
		SWPC	STAR SDO			SWPC	STAR	Current	Previous
11325	2011.10.19			N17W66						spotless
11330	2011.10.21 2011.10.22	12	28	N07W51	0400	EKI	CHI			beta-gamma location: N06W53
11333	2011.10.23 2011.10.27	2	1	N10W45	0010	AXX	AXX			location: N16W41
11332	2011.10.23 2011.10.24	1	3	N31W13	0020	HSX	HRX			location: N32W11
S1295	2011.10.25			S20W53						plage
S1296	2011.10.27			N17W16						plage
11335	2011.10.28 2011.10.31	2	5	N19E16	0010	BXO	CRO
S1299	2011.10.28			N16W23						plage
11336	2011.10.29 2011.10.31	1	10	N14E55	0010	AXX	DRO			beta-gamma
11334	2011.10.29 2011.10.30	11	17	N12E11	0110	CAO	DSO
11337	2011.10.30 2011.10.31	1	2	N17E66	0040	HSX	HRX			area: 0010
S1303	2011.10.31		4	S13E86	0250		DAO
S1304	2011.10.31		2	N20E06	0000		AXX
Total spot count:		30	72
Sunspot number:		100	162	(total spot count + 10 * number of spotted regions)
Classification adjusted SN:		55	104	(Sum of total spot count + classification adjustment for each AR. Classification adjustment: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number):		60	53	k * (sunspot number). k = 0.6 for SWPC. k = 0.33 for STAR SDO

Monthly solar cycle data

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 SIDC international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the preliminary 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.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.