Solar Terrestrial Activity Report

Last major update issued on January 7, 2013 at 05:55 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 quiet on January 6. Solar wind speed at SOHO ranged between 280 and 362 km/s, gradually increasing throughout the day, likely under the influence of a low speed coronal hole stream.

Solar flux measured at 20h UTC on 2.8 GHz was 142.2 (increasing 38.2 over the last solar rotation). The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.8). Three hour interval K indices: 00011121 (planetary), 01001321 (Boulder).

The background x-ray flux was at the class B5 level.

At midnight UTC the visible solar disk had 16 spotted active regions (in 2K resolution SDO images).

Region 11638 [N12W60] was quiet and stable.
Region 11640 [N27W74] was quiet and stable.
Region 11641 [N02W33] decayed slowly and quietly.
Region 11642 [S24W03] was quiet and stable.
Region 11643 [S14W08] decayed slowly and could soon become spotless.
Region 11644 [N15E09] was quiet and stable.
Region 11645 [S13W43] decayed slowly and quietly.
Region 11646 [N13E18] was quiet and stable.
Region 11647 [N17W78] decayed slowly and quietly.
Region 11648 [N06E26] decayed slowly and quietly.
Region 11649 [S15E46] was quiet and stable.
Region 11650 [S29E55] was quiet but could produce at least C flares.
Region 11651 [N20E24] decayed slowly and quietly.
Region 11652 [N19E65] produced a single C class event and was otherwise quiet and stable.
Region 11653 [N08E63] produced a few C flares and was the most active region on the visible disk.

Spotted regions not numbered by SWPC:
New region S2160 [S17E12] emerged with tiny spots.

Coronal mass ejections (CMEs)

January 4-6: 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 fair. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be mostly quiet on January 7-9, there's a chance of unsettled intervals due to 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
11639	2012.12.26 2012.12.27				S16W66						plage
11638	2012.12.26 2012.12.27	1	1	1	N13W61	0050	HSX	HSX			area: 0120
S2133	2012.12.28				N18W54						plage
11641	2012.12.29 2012.12.31	1	1	1	N02W33	0030	HSX	HSX
S2138	2012.12.29				N03W43						plage
11640	2012.12.29 2012.12.30	4	3	3	N28W75	0360	EHO	EHO			area: 0460
11642	2012.12.30 2012.12.31	1	5	3	S25W04	0090	HSX	CSO			area: 0180
11643	2012.12.31 2013.01.02		1		S14W11	0000		AXX			location: S14W08
11644	2013.01.01 2013.01.02	3	8	3	N15E09	0040	CSO	CSO			area: 0070
11648	2013.01.02 2013.01.04	6	8	3	N05E26	0030	CRO	BXO
11646	2013.01.02 2013.01.03	1	4	2	N13E17	0040	HSX	CSO			area: 0070
11651	2013.01.02 2013.01.04	1	2	1	N20E23	0010	AXX	AXX
11645	2013.01.02 2013.01.03	4	2		S13W45	0010	BXO	BXO
11647	2013.01.02 2013.01.04	3	1		N16W81	0020	CRO	AXX
11649	2013.01.03 2013.01.04	1	3	1	S15E46	0070	HSX	HSX			area: 0100
S2156	2013.01.03				N17E19						plage
11650	2013.01.04	9	21	8	S29E54	0240	EAO	EAO
11652	2013.01.05	8	18	10	N20E61	0120	DAO	EAO			location: N19E65
11653	2013.01.05	3	4	3	N09E63	0030	CSO	DAO
S2157	2013.01.05				S02E16						plage
S2158	2013.01.05				N15W25						plage
S2159	2013.01.05				N25W07						plage
S2160	2013.01.06		3		S17E12	0000		BXO
Total spot count:		46	85	39
Sunspot number:		186	245	159	(total spot count + 10 * number of spotted regions)
Weighted SN:		107	140	94	(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):		112	86	87	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.