Solar Terrestrial Activity Report

Last major update issued on January 24, 2013 at 04:05 UTC. Note: Updates will be irregular until January 28.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update January 1, 2013)] [Cycle 24 progress (last update January 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update January 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update January 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update January 2, 2013)]

[POES auroral activity level since October 2009 - updated October 7, 2012]
[Solar polar fields vs solar cycles - updated January 8, 2013]

Recent activity

The geomagnetic field was very quiet on January 23. Solar wind speed at SOHO ranged between 285 and 320 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 104.9 (decreasing 4.9 over the last solar rotation). The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.3). Three hour interval K indices: 01100001 (planetary), 01101110 (Boulder).

The background x-ray flux was at the class B1 level.

At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).

Region 11658 [S12W72] was quiet and stable.
Region 11659 [N06W28] reemerged with a tiny spot.
Region 11660 [N12W43] gained area in the leading spot section while decay was observed elsewhere.
Region 11661 [N14E47] was quiet and stable.
New region 11662 [N28E67] rotated into view on January 22 and was numbered by SWPC the next day.

Spotted regions not numbered by SWPC:
S2182 [N17W35] decayed slowly and quietly.
S2185 [S13W13] was quiet and stable.
S2187 [S29E20] was quiet and stable.
New region S2189 [S18E08] emerged with tiny spots.
New region S2190 [S30W39] emerged with a tiny spot.

Two interesting filament eruption were observed during the day. The southern polar crown filament erupted early in the day causing a large and wide CME. Another filament eruption was observed starting near 13:40 UTC to the west or AR 11662. The associated CME does not appear to be Earth directed.

Coronal mass ejections (CMEs)

January 22-24: 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 coronal hole (CH550) in the southern hemisphere was in an Earth facing position on January 21-22, however, CH550 closed 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 good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on January 24 and 26. On January 25 there's a chance of weak effects arriving from CH550 causing occasional unsettled intervals.

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 2K resolution) Compare to the previous day's image. 0.5k 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
			2K	1K
11658	2013.01.12 2013.01.13	1	1	1	S12W73	0060	HSX	HSX			area: 0080
11659	2013.01.16 2013.01.17		1		N04W33	0000		AXX			location: N06W28
11660	2013.01.17 2013.01.19	25	22	14	N13W42	0200	DAI	DAI			location: N12W43
S2182	2013.01.17		3		N17W35	0000		AXX
S2184	2013.01.18				N15W13						plage
S2185	2013.01.20		2		S13W13	0000		AXX
11661	2013.01.21 2013.01.22	1	3	2	N13E56	0020	CSO	HRX
S2187	2013.01.22		3	1	S29E20	0000		BXO
11662	2013.01.22 2013.01.23	1	1	1	N26E64	0060		HSX
S2189	2013.01.23		2		S18E08	0000		AXX
S2190	2013.01.23		1		S30W39	0000		AXX
Total spot count:		28	39	19
Sunspot number:		68	139	69	(total spot count + 10 * number of spotted regions)
Weighted SN:		48	57	37	(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):		41	49	38	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K

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) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.