Solar Terrestrial Activity Report

Last major update issued on January 5, 2013 at 05:10 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 very quiet on January 4. Solar wind speed at SOHO ranged between 278 and 370 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 143.1 (increasing 42.0 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: 1.1). Three hour interval K indices: 10000000 (planetary), 00000211 (Boulder).

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

At midnight UTC the visible solar disk had 14 spotted active regions (in 2K resolution SDO images).

Region 11638 [N13W33] decayed slowly and quietly.
Region 11639 [S17W33] remeerged with tiny spots.
Region 11640 [N28W48] lost approximately half of its spots while the main penumbrae increased their area. The region has a fairly simple magnetic layout.
Region 11641 [N03W05] was quiet and stable.
Region 11642 [S24E23] was quiet and stable.
Region 11643 [S14E18] was quiet and stable.
Region 11644 [N15E36] was quiet and stable.
Region 11645 [S13W17] decayed slowly and quietly.
Region 11646 [N13E45] was quiet and stable.
New region 11647 [N16W53] emerged on January 2 and got its NOAA number 2 days later.
New region 11648 [N04E53] rotated into view on January 2 and developed on Jan.4 when it was numbered by SWPC.
New region 11649 [S14E71] rotated into view on January 3.
New region 11650 [S27E76] rotated partly into view.
New region 11651 [N20E50] rotated into view onn January 2 and was numbered by SWPC 2 days later.

An interesting region is just behind the northeast limb and will likely rotate into view today.

Coronal mass ejections (CMEs)

January 2-4: 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) will be 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 5-6. Quiet to unsettled conditions are possible on January 7 due to weak effects from CH549.

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
11637	2012.12.24 2012.12.26				N06W77						plage
11636	2012.12.24 2012.12.25				N14W69						plage
11639	2012.12.26 2012.12.27		3		S16W38
11638	2012.12.26 2012.12.27	1	3	1	N13W34	0080	HSX	CSO			area: 0160
S2132	2012.12.26				S14W58						plage
S2133	2012.12.28				N18W28						plage
S2135	2012.12.28				S17W48						plage
11641	2012.12.29 2012.12.31	2	5	3	N04W05	0040	CAO	CSO			location: N03W05 area: 0080
S2138	2012.12.29				N03W30						plage
11640	2012.12.29 2012.12.30	24	15	8	N28W48	0320	EKI	EKO			area: 0500
S2142	2012.12.29				N13W49						plage
11642	2012.12.30 2012.12.31	1	5	2	S24E22	0100	HSX	CSO			location: S24E36 area: 0180
11643	2012.12.31 2013.01.02		4	2	S14E17	0000		BXO
11644	2013.01.01 2013.01.02	1	2	1	N15E36	0040	HSX	HSX
11648	2013.01.02 2013.01.04	2	8	6	N05E53	0020	CRO	DAO
11646	2013.01.02 2013.01.03	1	2	1	N14E45	0030	HAX	CSO			area: 0080
11651	2013.01.02 2013.01.04	1	1	1	N19E48	0010	AXX	HRX			location: N20E50
11645	2013.01.02 2013.01.03	8	10	5	S13W18	0050	DAO	DRO			area: 0030
S2153	2013.01.02				N16W51			BXO			merged with AR 11647
11647	2013.01.02 2013.01.04	4	7	3	N16W55	0030	CAO	CAO			area: 0060
11649	2013.01.03 2013.01.04	1	1	1	S14E74	0060	HSX	HSX			area: 0100
S2156	2013.01.03				N17E44						plage
11650	2013.01.04	1	2	2	S26E77	0050	HSX	CSO			area: 0220
Total spot count:		47	68	36
Sunspot number:		167	208	166	(total spot count + 10 * number of spotted regions)
Weighted SN:		105	129	97	(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):		100	73	91	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.