Solar Terrestrial Activity Report

Last major update issued on January 24, 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 5, 2012)]

[POES auroral activity level since October 2009 - updated January 23, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2117 [November-December 2011] - 2118 [December 2011 - January 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to minor storm on January 23. Solar wind speed ranged between 350 and 454 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 144.3 (increasing 4.0 over the last solar rotation). The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 10.9). Three hour interval K indices: 53211212 (planetary), 43201111 (Boulder).

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

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

Region 11399 [S20W45] reemerged with a single tiny spot.
Region 11401 [N16W42] decayed further losing all penumbra on the trailing spots. Flare: C1.4 at 20:11 UTC
Region 11402 [N30W35] changed significantly after the major flare as the large penumbra fragmented into smaller penumbrae. There's a magnetic delta structure in the easternmost of the new penumbrae. Further major flares are possible. Flares: M1.1/1N long duration event peaking at 03:04 (associated with a fast, wide asymmetric full halo CME), major M8.7/2B long duration event peaking at 03:59 UTC. The latter event was associated with another fast, asymmetric full halo CME and a strong radiation event. The above 10 MeV proton flux has so far peaked above 3600 pfu but could reach significantly higher values when the CMEs reach Earth. ACE solar wind speed, density and temperature became invalid after approx. 06:30 UTC due to sensor contamination.
Region 11405 [N12W23] decayed slowly and quietly.
Region 11407 [N18W54] decayed significantly and could soon become spotless.
Region 11408 [N08E44] was quiet and stable.
Region 11409 [N16E26] was quiet and stable.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1441] rotated into view at the southeast limb on January 22. Location at midnight: S14E63
[S1444] emerged in the northern hemisphere near the central meridian on January 22. Location at midnight: N13W16

Coronal mass ejections (CMEs)

January 21-22: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
January 23: Two halo CMEs were observed after the M1.1 and M8.7 LDEs in region 11402. The presence of two CMEs was observable in LASCO imagery, although it is likely the CMEs will have merged before reaching Earth.

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 small coronal hole (CH495) in the southern hemisphere was in an Earth facing position on January 20. A large recurrent coronal hole (CH496) in the southern hemisphere will rotate into an Earth facing position on January 23-25. CH496 extended significantly in its northwestern part on January 23 and could merge with CH497. A new, small coronal hole (CH497) was Earth facing on January 22.

The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, 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 this method, the extent and intensity of both CHs 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 very poor. Propagation on long distance northeast-southwest paths is fair to good.

Forecast

The geomagnetic field is expected to be unsettled to major storm on January 24-25 due to CME effects, severe storm intervals are possible. A high speed stream from CH496 could cause quiet to active conditions on January 26-28.

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
11399	2012.01.13 2012.01.14		1	S23W53	0000		AXX
11401	2012.01.14	22	28	N16W39	0170	ESO	DAI			beta-gamma location: N16W42
11402	2012.01.14	11	27	N29W23	0290	CKO	DKC			beta-gamma-delta location: N30W35 area: 0500
11403	2012.01.14 2012.01.15			S19W80						plage
11405	2012.01.15 2012.01.16	5	3	N13W24	0030	CSO	BXO			location: N12W23
S1436	2012.01.16			N16W27						plage
11407	2012.01.18	5	7	N16W53	0050	DSO	BXO			location: N18W54
11409	2012.01.20 2012.01.21	3	2	N09E27	0100	CAO	BXO			location: N16E26 area: 0000 SWPC has apparently mixed data from regions 11408 and 11409
11408	2012.01.20 2012.01.21	2	4	N08E44	0100	HSX	CSO
S1441	2012.01.22		2	S14E63	0010		AXX
S1442	2012.01.22			N12E06						plage
S1443	2012.01.22			N17W07						plage
S1444	2012.01.22		6	N13W16	0040		DRO
S1445	2012.01.22			N50W00						plage
Total spot count:		48	80
Sunspot number:		108	170	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		83	103	(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):		65	77	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.