Solar Terrestrial Activity Report

Last major update issued on January 13, 2012 at 05:05 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 5, 2012)]

[POES auroral activity level since October 2009 - updated January 11, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2116 [October-November 2011] - 2117 [November-December 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet on January 12. Solar wind speed ranged between 376 and 505 km/s. A high speed stream associated with CH492 arrived at ACE near 17h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 116.8 (decreasing 4.2 over the last solar rotation). The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 20012222 (planetary), 21022212 (Boulder).

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

At midnight UTC the visible solar disk had 7 spotted regions (in 2K resolution SDO images).

Region 11391 [N12W53] decayed in the trailing spot section while quick development was observed in the southeastern part of the leading spot section. A magnetic delta structure has formed and the region could produce a minor M class flare.
Region 11395 [N22E08] decayed slowly and was mostly quiet. Flare: C1.5 at 00:58 UTC
New region 11396 [N26E33] emerged in the northeast quadrant on January 9, was spotless the next day, then reemerged on January 11 with SWPC assigning its number the following day.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1424] rotated into view at the southeast limb on January 11. Location at midnight: S16E60
[S1425] emerged in the northeast quadrant on January 11. Location at midnight: N14E04
[S1426] emerged in the southeast quadrant on January 12. Location at midnight: S20E42
[S1427] emerged in the southeast quadrant on January 12. Location at midnight: S24E34

A region just behind the northeast limb produced a very long duration C2.5 event peaking at 10:01 UTC. This event was associated with a large and wide CME.

A reversed polarity region with a spot slightly too small to be counted was located at S37W54 at midnight.

Coronal mass ejections (CMEs)

January 10-12: 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 coronal hole (CH492) in the southern hemisphere was in an Earth facing position on January 9-10. A recurrent trans equatorial coronal hole (CH493) was in an Earth facing position on January 12.

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 to fair. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 13 due to weak effects from CH492. Quiet conditions are likely on January 14 becoming quiet to unsettled on January 15-16 due to effects from CH493.

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
11391	2012.01.02	11	19	N12W51	0180	CAO	DAI			beta-gamma-delta location: N12W53
11394	2012.01.05 2012.01.06			N18W42						plage
S1411	2012.01.06			S20W18						plage
11395	2012.01.07 2012.01.08	2	6	N21E07	0070	HSX	HSX
S1415	2012.01.07			N12W25						plage
S1419	2012.01.08			S22W29						plage
S1420	2012.01.09			N30W41						plage
11396	2012.01.09 2012.01.12	2	12	N25E32	0010	BXO	DRI			area: 0070
S1422	2012.01.10			S16W04						plage
S1423	2012.01.10			S26E05						plage
S1424	2012.01.11		1	S16E60	0000		AXX
S1425	2012.01.11		1	N14E04	0000		AXX
S1426	2012.01.12		3	S20E42	0010		HRX
S1427	2012.01.12		1	S24E34	0000		AXX
Total spot count:		15	43
Sunspot number:		45	113	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		25	59	(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):		27	51	k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1, 2011) 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.