Solar Terrestrial Activity Report

Last major update issued on January 3, 2012 at 04:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update January 2, 2012)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update Jauary 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update January 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update January 3, 2012)]

[POES auroral activity level since October 2009 - updated January 2, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2116 [October-November 2011] - 2117 [November-December 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet on January 2. Solar wind speed ranged between 344 and 471 km/s. An unexpected solar wind disturbance began after 17h UTC, solar wind parameters indicate a CME origin.

Solar flux measured at 20h UTC on 2.8 GHz was 134.7 (decreasing 16.4 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.9). Three hour interval K indices: 00002122 (planetary), 10113222 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight UTC the visible solar disk had 8 spotted regions (in 2K resolution SDO images).

Region 11388 [S23W08] was quiet and stable.
Region 11389 [S16E05] added a few spots and has reversed polarities. Note that SWPC includes region S1401 in this region.
Region 11390 [N11W30] developed many new spots as new flux emerged.
New region 11391 [N12E82] rotated partly into view at the northeast limb. The leader penumbra is large and extends 4 degrees latitudinally. M flares are posssible.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1392] rotated into view at the southeast limb on December 23, slow decay has been observed since Dec.30. Location at midnight: S18W55
[S1401] rotated into view at the southeast limb on December 28 and developed significantly in the central and trailing spot sections on Dec.29-31. The leading spot section decayed on January 1. Quick decay was observed on January 2, particuarly in the trailing spot section. Location at midnight: S23E10. Flares: C1.6 at 05:28, C1.5 at 07:24 UTC.
[S1406] emerged in the northeast quadrant on January 2. Location at midnight: N10E43
[S1407] emerged in the northeast quadrant on January 2. Location at midnight: N21E24

The most significant event of the day was a long duration C2.4 event peaking at 15:24 UTC from a source just behind the northwest limb. This event was associated with a minor proton flux enhancement.

Coronal mass ejections (CMEs)

December 31 - January 2: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

Coronal holes

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

A recurrent trans equatorial coronal hole (CH491) will likely rotate into an Earth facing position on January 4-5.

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 January 3 and quiet on January 4-6. A high speed stream from CH491 could cause some unsettled and active intervals on January 7-8.

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
11386	2011.12.22 2011.12.23	1		S17W57	0050	HSX				spotless location: S16W59 SWPC includes region S1392
S1392	2011.12.23		3	S18W55	0080		CSO
11388	2011.12.26 2011.12.27	1	5	S24W14	0060	HSX	CSO			area: 0120 location: S23W08
11389	2011.12.27 2011.12.28	21	5	S22E08	0330	FKC	CHO			reversed polarities area: 0320 location: S16E05 SWPC includes region S1401
S1400	2011.12.27			N17W36						plage
S1401	2011.12.28		32	S23E10	0130		EAO
11390	2011.12.28	9	15	N10W29	0010	BXO	DRI			location: N11W30 area: 0040
S1403	2011.12.30			N24W25						plage
S1404	2011.12.30			N11W47						plage
S1405	2011.12.31			N15E01						plage
11391	2012.01.02	1	6	N13E81	0120	HSX	DHO			location: N12E82 area: 0550
S1406	2012.01.02		1	N10E43	0000		AXX
S1407	2012.01.02		11	N21E24	0020		BXO
Total spot count:		33	78
Sunspot number:		83	158	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		58	116	(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):		50	71	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.