Solar Terrestrial Activity Report

Last major update issued on January 21, 2012 at 06:10 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 20, 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 20. Solar wind speed ranged between 284 and 374 km/s. A weak solar wind shock was observed near 04h UTC at ACE on January 21. Taking into account the low solar wind speed this event may be related to the CME observed on January 16.

Solar flux measured at 20h UTC on 2.8 GHz was 141.2 (decreasing 1.6 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.5). Three hour interval K indices: 11211111 (planetary), 21211211 (Boulder).

The background x-ray flux is at the class B7 level.

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

Region 11399 [S22W12] decayed slowly and quietly.
Region 11401 [N17W01] decayed in the trailing and central spot sections. Two weak magnetic delta structures formed at the southern edge of the largest penumbra. M class flares are possible.
Region 11402 [N30E04] remains capable of producing further M class flares. A weak magnetic delta structure is visible in the western part of the large penumbra.
Region 11403 [S18W35] decayed further and could soon become spotless.
Region 11405 [N12E16] developed slowly and quietly.
Region 11407 [N18W13] developed slowly and quietly.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1437] reemerged with spots on January 19. Location at midnight: N17W44
[S1439] emerged in the northeast quadrant on January 20. Location at midnight: N17E65
[S1440] rotated into view at the northeast limb on January 20. Location at midnight: N08E84

Coronal mass ejections (CMEs)

January 20: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery
January 19: A full halo CME was observed after the M3.2 LDE in region 11402. The CME will likely reach Earth on January 21 and could cause active to major storm conditions (strong southward IMF fluctuations are possible taking into consideration the magnetic layout and intensity in the area where the eruption occurred).
January 18: A partial halo CME was observed after a filament eruption in the southern hemisphere near the central meridian. Activity increased in the filament after 08:50 UTC until eruption several hours later.

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 could rotate into an Earth facing position on January 24-26.

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 becoming very poor at near polar latitudes due to elevated proton levels. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to active on January 21 due to CME effects, if the CME observed on Janaury 19 arrives late in the day, disturbance levels could increase to major storm. On January 22 unsettled to major storm conditions are possible due to CME effects. Quiet to unsettled is likely on January 23-24.

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
11396	2012.01.09 2012.01.12			N25W72						plage
S1424	2012.01.11			S16W44						plage
11397	2012.01.12 2012.01.13			S20W68						plage
11399	2012.01.13 2012.01.14		5	S23W11	0000		BXO
11401	2012.01.14	19	27	N16W00	0380	EKI	FKI			beta-gamma-delta location: N17W01 area: 0500
11402	2012.01.14	9	19	N28E03	0310	DKI	DKO			beta-gamma-delta location: N30E04 area: 0500
11403	2012.01.14 2012.01.15		1	S19W38	0000		AXX			location: S18W35
S1431	2012.01.14			N10W48						plage
11405	2012.01.15 2012.01.16	1	10	N11E13	0030	HSX	CSO			location: N12E16
11404	2012.01.15 2012.01.16			N11W84						plage
S1436	2012.01.16			N16E12						plage
S1437	2012.01.16		1	N17W44	0000		AXX
11407	2012.01.18	8	15	N17W13	0050	DSO	DAO
S1439	2012.01.20		1	N17E65	0010		AXX
S1440	2012.01.20		1	N08E84	0100		HSX
Total spot count:		37	80
Sunspot number:		77	170	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		67	115	(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):		46	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.