Solar Terrestrial Activity Report

Last major update issued on December 8, 2013 at 06:35 UTC.

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

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated December 3, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet on December 7. Solar wind speed at SOHO ranged between 275 and 479 km/s. A low speed stream associated with CH596 caused a slow increase in solar wind speed and density after 14h UTC at ACE. A CME was observed arriving at SOHO at 21:38 UTC, probably associated with a large filament eruption in the northern hemisphere on December 4. The interplanetary magnetic field was strongly southwards early on December 8 causing minor geomagnetic storm conditions.

Solar flux measured at 20h UTC on 2.8 GHz was 156.9 (increasing 2.8 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 129.5. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.3). Three hour interval K indices: 21100012 (planetary), 11301213 (Boulder).

The background x-ray flux was at the class B8 level.

At the time of counting spots (see image time) spots were observed in 11 active regions in 2K resolution (SN: 253) and 6 active regions in 1K resolution (SN: 120) SDO images on the visible solar disk.

Region 11909 [S17W61] decayed further. C5++ flare: M1.2/1N at 07:29 UTC. This event was associated with a wide CME which could have an Earth directed extension.
Region 11912 [S21E02] was quiet and stable.
Region 11915 [S30W60] decayed slowly and quietly.
Region 11916 [S12W24] gained spots and penumbral area. C and M class flares are possible. The region has polarity intermixing.
New region 11917 [S16E68] rotated into view on December 6 and was numbered the next day by SWPC. The region has M class flare potential.

Spotted regions not numbered by SWPC:
S2876 [S13W37] decayed slowly and quietly.
S2892 [S14E40] developed and has polarity intermixing.
New region S2896 [N12E75] rotated into view with penumbra spots.
New region S2897 [N16E41] emerged with one spot.
New region S2898 [N20E18] emerged with a penumbra spot.
New region S2899 [S53W28] emerged at a high latitude with a penumbra spot.

Coronal mass ejections (CMEs)

December 5: A filament eruption was observed near AR 11909 starting at 20:41 UTC in SDO/AIA imagery. STEREO imagery indicate that there was a CME associated with this event and that it could have an Earth directed component.
December 6: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
December 7: A CME was observed in STEREO imagery after an M1 event in AR 11909. The CME was wide and could have an Earth directed extension.

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 large northern hemisphere coronal hole (CH597) will likely rotate into an Earth facing position on December 11.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair to good.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on December 8 due to CME effects. Quiet to unsettled conditions are likely on December 9-10.

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 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
11909	2013.11.26 2013.11.27	7	5	2	S17W61	0100	CSO	CSO			location: S18W63
11911	2013.11.29 2013.11.28				S11W78						plage
11914	2013.11.29 2013.12.02				S18W89						plage
S2871	2013.11.30				N21W25						plage
S2876	2013.12.01		1		S13W37	0001		AXX
11912	2013.12.01 2013.12.02	1	15	4	S21E01	0120	HSX	CSO			area: 0180
S2878	2013.12.01				S27W34						plage
11915	2013.12.01 2013.12.03	4	2		S30W59	0010	BXO	BXO			area: 0004
S2881	2013.12.02				N10W53						plage
S2882	2013.12.02				N24W45						plage
S2886	2013.12.03				S27W36						plage
S2887	2013.12.03				N08W27						plage
11916	2013.12.04	34	68	36	S13W25	0220	DAI	DAC			beta-gamma area: 0500
S2890	2013.12.04				S10W48						plage
S2892	2013.12.04		28	8	S14E40	0055		BXI
11917	2013.12.06 2013.12.07	8	18	9	S16E63	0060	DAO	CAI			beta-gamma area: 0300 location: S16E68
S2895	2013.12.06				N33W45						plage
S2896	2013.12.07		3		N12E75	0010		AXX
S2897	2013.12.07		1	1	N16E41	0007		AXX
S2898	2013.12.07		1		N20E18	0003		AXX
S2899	2013.12.07		1		S53W28	0002		AXX
Total spot count:		54	143	60
Sunspot number:		104	253	120	(total spot count + 10 * number of spotted regions)
Weighted SN:		74	163	80	(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):		62	89	66	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 the 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.