Solar Terrestrial Activity Report

Last major update issued on January 6, 2013 at 06:05 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 December 22, 2012]

Recent activity

The geomagnetic field was inactive on January 5. Solar wind speed at SOHO ranged between 272 and 336 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 145.1 (increasing 41.4 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: 00000000 (planetary), 11012211 (Boulder).

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

At midnight UTC the visible solar disk had 19 spotted active regions (in 2K resolution SDO images).

Region 11638 [N12W47] decayed slowly and quietly.
Region 11640 [N28W61] matured losing small spots with little overall change in penumbral area.
Region 11641 [N02W19] decayed slowly and quietly.
Region 11642 [S24E10] was quiet and stable.
Region 11643 [S14E07] was quiet and stable.
Region 11644 [N15E23] was quiet and gained several tiny spots.
Region 11645 [S13W30] decayed slowly and quietly.
Region 11646 [N13E32] was quiet and stable.
Region 11647 [N15W67] decayed quickly and was quiet.
Region 11648 [N04E40] lost penumbral area and was quiet.
Region 11649 [S15E59] was quiet and stable.
Region 11650 [S28E65] rotated fully into view. There could be a small magnetic delta structure in a trailing penumbra. The region produced several small C flares during the day. C and minor M class flaring is possible.
Region 11651 [N20E37] was quiet and stable.
New region 11652 [N19E77] rotated partly into view. The region produced the only interesting flare of the day, an M1.7 event at 09:31 UTC.
New region 11653 [N08E77] rotated into view and produced a small C flare late in the day.

Spotted regions not numbered by SWPC:
S2156 [N17E32] reemerged with a tiny spot.
New region S2157 [S02E29] emerged with the polarity layout of a northern hemisphere region.
New region S2158 [N15W12] emerged with tiny spots.
New region S2159 [N25E06] emerged with a tiny spot in an old plage area.

Coronal mass ejections (CMEs)

January 3-5: 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 6. Quiet to unsettled conditions are likely on January 7-8 due to weak effects from CH549, active intervals are possible.

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
11636	2012.12.24 2012.12.25				N14W83						plage
11639	2012.12.26 2012.12.27				S16W52						plage
11638	2012.12.26 2012.12.27	1	2	1	N13W48	0040	HSX	CSO			area: 0140
S2133	2012.12.28				N18W41						plage
11641	2012.12.29 2012.12.31	3	3	1	N04W20	0040	HSX	CSO			location: N02W19 area: 0060
S2138	2012.12.29				N03W30						plage
11640	2012.12.29 2012.12.30	11	5	4	N28W62	0330	EKI	EKO			area: 0460
11642	2012.12.30 2012.12.31	1	7	1	S24E10	0080	HSX	CSO			area: 0180
11643	2012.12.31 2013.01.02		5	1	S14E03	0000		BXO			location: S14E07
11644	2013.01.01 2013.01.02	4	10	4	N15E20	0050	CSO	CSO			location: N15E23
11648	2013.01.02 2013.01.04	3	10	6	N05E40	0040	CAO	DRO
11646	2013.01.02 2013.01.03	1	2	1	N14E31	0030	HSX	HSX			area: 0080
11651	2013.01.02 2013.01.04	1	1	1	N20E35	0010	AXX	HRX			location: N20E37
11645	2013.01.02 2013.01.03	5	12	5	S14W32	0030	CSO	BXO			area: 0010
11647	2013.01.02 2013.01.04	3	3	3	N15W69	0030	CAO	BXO
11649	2013.01.03 2013.01.04	1	1	1	S15E60	0080	HSX	HSX			area: 0100
S2156	2013.01.03		1	1	N17E32	0000		AXX
11650	2013.01.04	5	10	6	S28E63	0190	EAO	EAO			area: 0300
11652	2013.01.05	1	8	2	N20E74	0060	HSX	DAO			area: 0130 location: N19E77
11653	2013.01.05	1	3	2	N09E78	0020	HRX	CSO
S2157	2013.01.05		1		S02E29	0000		AXX
S2158	2013.01.05		2		N15W12	0000		AXX
S2159	2013.01.05		1		N25E06	0000		AXX
Total spot count:		41	87	40
Sunspot number:		181	277	200	(total spot count + 10 * number of spotted regions)
Weighted SN:		109	148	101	(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):		109	97	110	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.