Solar Terrestrial Activity Report

Last major update issued on January 16, 2012 at 05:25 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 14, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2117 [November-December 2011] - 2118 [December 2011 - January 2012] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet on January 15. Solar wind speed ranged between 326 and 416 km/s. A relatively low speed stream from CH493 arrived at ACE after 15h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 133.5 (increasing 5.3 over the last solar rotation). The planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.5). Three hour interval K indices: 00000112 (planetary), 01002212 (Boulder).

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

At midnight UTC the visible solar disk had 13 spotted regions (in 2K resolution SDO images).

Region 11395 [N22W31] decayed slowly and quietly.
Region 11396 [N26W05] lost penumbral area and gained a few spots.
Region 11397 [S19E05] decayed slowly and quietly.
Region 11398 [N13W36] lost many spots and was quiet.
Region 11399 [S23E56] decayed slowly and quietly.
Region 11401 [N17E66] has polarity intermixing and could produce C and minor M class flares. The region displayed significantly less activity than during the previous day.
Region 11402 [N28E67] was mostly quiet and remains capable of producing an M class flare. This region was the source of a very long duration C6.4 event peaking between 04 and 05 UTC on January 16. An associated CME is visible in STEREO-B images.
New region 11403 [S18E28] emerged in the southeast quadrant on January 14 and got an SWPC number the following day.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1431] emerged in the northeast quadrant on January 14. Location at midnight: N11E18
[S1432] emerged in the northeast quadrant on January 14. Location at midnight: N13W04
[S1433] emerged in the southwest quadrant on January 14. Location at midnight: S30W53
[S1434] rotated into view at the northeast limb on January 15. Location at midnight: N12E81
[S1435] emerged in the northwest quadrant on January 15. Location at mdnight: N13W15

Coronal mass ejections (CMEs)

January 13-15: 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 (CH493) was in an Earth facing position on January 12-13. A trans equatorial coronal hole (CH494) could rotate into an Earth facing position on January 17.

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 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 16-17 due to effects from CH493. Quiet conditions are likely on January 18-20 with a chance of unsettled intervals on January 20 due to effects from CH494.

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
11394	2012.01.05 2012.01.06			N18W84						plage
S1411	2012.01.06			S20W57						plage
11395	2012.01.07 2012.01.08	2	2	N20W31	0010	HSX	HRX			location: N22W31
11396	2012.01.09 2012.01.12	10	21	N25W07	0080	DAO	DAI			location: N26W05
S1422	2012.01.10			S16W43						plage
S1423	2012.01.10			S26W34						plage
S1424	2012.01.11			S16E21						plage
11398	2012.01.11 2012.01.13	9	12	N12W36	0050	DAO	DSI
11397	2012.01.12 2012.01.13	3	4	S20E02	0015	CAO	BXO			location: S19E05
S1427	2012.01.12			S24W05						plage
11399	2012.01.13 2012.01.14	2	2	S23E54	0020	HAX	HRX
11400	2012.01.13 2012.01.14	2		S13W17	0010	CSO				spotless
11401	2012.01.14	14	14	N17E60	0200	DAI	EHI			area: 0380 location: N17E66
11402	2012.01.14	7	8	N27E64	0270	DHO	DHO			area: 0600 location: N28E67
11403	2012.01.14 2012.01.15	2	4	S19E29	0010	BXO	BXO
S1431	2012.01.14		1	N11E18	0000		AXX
S1432	2012.01.14		1	N13W04	0000		AXX
S1433	2012.01.14		3	S30W53	0000		BXO
S1434	2012.01.15		1	N12E81	0040		HSX
S1435	2012.01.15		5	N13W15	0030		DRO
Total spot count:		51	78
Sunspot number:		141	208	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		96	122	(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):		85	94	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.