Solar Terrestrial Activity Report

Last major update issued on December 3, 2011 at 06:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update December 1, 2011)] - new cycle peak projection
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update December 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update December 2, 2011)]

[POES auroral activity level since October 2009 - updated December 2, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2114 [August-September 2011] - 2115 [September-October 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on December 2. Solar wind speed ranged between 347 and 466 km/s. A weak solar wind disturbance was observed beginning at ACE after 16h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 157.3 (decreasing 14.6 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.3). Three hour interval K indices: 10100131 (planetary), 10200222 (Boulder).

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

At midnight UTC the visible solar disk had 11 spotted regions (in 2K resolution SDO images).

Region 11358 [N21W56] decayed slowly and quietly.
Region 11361 [N20W33] has weak polarity intermixing and is decaying slowly.
Region 11362 [N09E10] displayed no major changes and remains capable of producing C flares.
Region 11363 [S16E28] was quiet and stable.
Region 11364 [N21E37] was quiet and stable.
New region 11365 [N22E16] emerged in the northeast quadrant on December 1 and was numbered the next day by SWPC. The region developed fairly quickly on Dec.2. C flares are possible.

Spotted regions not reported by NOAA/SWPC:
[S1338] emerged in the northeast quadrant on Nov.26, became spotless, then reemerged on December 2. Location at midnight: N17W18
[S1342] rotated into view at the southeast limb on Nov.28. The region developed quickly on Dec.1-2 and could produce minor M class flares. There's weak polarity intermixing. Location at midnight: S22E33.
[S1343] emerged in the southeast quadrant on November 29, became spotless and reemerged on Dec.2. Location at midnight: S14E18
[S1344] emerged in the northeast quadrant on November 30. Location at midnight: N24E03
[S1347] rotated into view at the northeast limb on December 2. Location at midnight: N18E78

Coronal mass ejections (CMEs)

November 30 - December 2: 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

No obvious coronal holes are near potentially geoeffective positions.

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.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 3 and quiet on December 4-5.

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 magnetic polarity overlay		Comment
		SWPC	STAR SDO			SWPC	STAR	Current	Previous
11358	2011.11.22	3	6	N20W54	0090	CSO	CSO			location: N21W56
11361	2011.11.24 2011.11.25	7	26	N20W32	0060	DSO	DSI			beta-gamma area: 0120
S1337	2011.11.25			S17W12						plage
S1338	2011.11.26		2	N17W18	0000		AXX
11362	2011.11.27	12	27	N08E08	0170	DSI	ESI			area: 0370
11363	2011.11.28 2011.11.29	15	4	S20E29	0250	EHI	HSX			location: S16E28 area: 0080 SWPC includes S1342 in this region
11364	2011.11.28 2011.11.29	4	7	N19E34	0040	CSO	CSO			area: 0110 location: N20E49
S1342	2011.11.28		41	S22E33	0600		EAC			beta-gamma
S1343	2011.11.29		6	S14E18	0000		BXO
S1344	2011.11.30		3	N24E03	0000		AXX
11365	2011.12.01 2011.12.02	5	16	N20E13	0020	CSO	DRI			location: N22E16 area: 0060
S1347	2011.12.02		3	N18E78	0100		HSX
Total spot count:		46	141
Sunspot number:		106	251	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		81	179	(Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number):		64	113	k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1) 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.