Solar Terrestrial Activity Report

Last major update issued on January 8, 2013 at 06:15 UTC.

[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 7. Solar wind speed at SOHO ranged between 328 and 378 km/s under the influence of a very weak stream from CH549.

Solar flux measured at 20h UTC on 2.8 GHz was 149.7 (increasing 46.0 over the last solar rotation). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.9). Three hour interval K indices: 10001001 (planetary), 10111211 (Boulder).

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

At midnight UTC the visible solar disk had 18 spotted active regions (in 2K resolution SDO images).

Region 11638 [N12W74] was quiet and stable.
Region 11640 [N28W84] produced a few C flares as it rotated to the northwest limb.
Region 11641 [N01W47] decayed slowly and quietly.
Region 11642 [S24W15] was quiet and stable.
Region 11643 [S14W23] was quiet and stable.
Region 11644 [N15W04] was quiet and stable.
Region 11645 [S14W57] developed slowly and quietly.
Region 11646 [N13E06] decayed with the largest spot displaying internal fragmentation.
Region 11648 [N05E15] was quiet and stable.
Region 11649 [S15E33] was quiet and stable.
Region 11650 [S29E41] was quiet and stable.
Region 11651 [N27E17] lost the original spots with a new spot emerging in the northeastern corner of the trailing polarity field.
Region 11652 [N20E51] developed slowly and could produce C and M class flares.
Region 11653 [N08E50] added a few spots and could produce C flares.

Spotted regions not numbered by SWPC:
New region S2160 [S15W03] was quiet and stable.
New region S2161 [N08E85] rotated into view with a large spot.
New region S2162 [N20E25] emerged with a tiny spot.
New region S2163 [S17E07] emerged with a tiny spot.

Coronal mass ejections (CMEs)

January 5-7: 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 small recurrent trans equatorial coronal hole (CH549) was in an Earth facing position on January 3-4.

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

Forecast

The geomagnetic field is expected to be quiet on January 8-10.

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
11639	2012.12.26 2012.12.27				S16W80						plage
11638	2012.12.26 2012.12.27	1	1	1	N13W74	0080	HSX	HSX
11641	2012.12.29 2012.12.31	1	1	1	N02W48	0010	HRX	AXX
S2138	2012.12.29				N03W56						plage
11640	2012.12.29 2012.12.30	5	1	1	N28W87	0300	EHO	HSX
11642	2012.12.30 2012.12.31	1	6	3	S25W16	0120	HSX	CSO			area: 0170
11643	2012.12.31 2013.01.02		2	1	S14W25	0000		AXX			location: S14W23
11644	2013.01.01 2013.01.02	1	6	2	N15W06	0060	HSX	HSX
11648	2013.01.02 2013.01.04	1	7	5	N05E10	0010	AXX	BXO
11646	2013.01.02 2013.01.03	1	8	3	N13E04	0060	HSX	CAO
11651	2013.01.02 2013.01.04		1		N20E09	0000		AXX
11645	2013.01.02 2013.01.03	2	8	6	S14W58	0010	BXO	DRO
11649	2013.01.03 2013.01.04	1	4	2	S16E32	0140	HSX	HSX
S2156	2013.01.03				N17E06						plage
11650	2013.01.04	22	23	10	S29E41	0250	EHO	EAO
11652	2013.01.05	34	45	27	N17E50	0320	FKC	EAC			beta-gamma location: N20E51
11653	2013.01.05	6	7	4	N07E49	0030	CRO	DAO
S2157	2013.01.05				S02E03						plage
S2158	2013.01.05				N15W38						plage
S2159	2013.01.05				N25W20						plage
S2160	2013.01.06		4	1	S15W03	0000		BXO
S2161	2013.01.07		1	1	N08E85	0520		HHX
S2162	2013.01.07		1	1	N20E25	0000		AXX
S2163	2013.01.07		1	1	S17E07	0000		AXX
Total spot count:		76	127	70
Sunspot number:		196	307	240	(total spot count + 10 * number of spotted regions)
Weighted SN:		137	185	128	(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):		118	107	132	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.