Solar Terrestrial Activity Report

Last major update issued on October 9, 2013 at 05:45 UTC.

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

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated September 24, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to minor storm on October 8. Solar wind speed at SOHO ranged between 272 and 651 km/s. A strong solar wind shock was observed near 19:40 at ACE. The source of this unexpected disturbance is likely a faint full halo CME observed on October 6 (from 14:24 UTC in STEREO-A, after 15 UTC in LASCO). An eruption near the central meridian at close to S10 was observed at 13:45 UTC on that day. At SOHO the initial part of the CME was extremely dense peaking above 120 p/cm3. The interplanetary magnetic field swing strongly southwards for a few hours after the arrival of the shock and caused minor storm conditions.

Solar flux measured at 20h UTC on 2.8 GHz was 111.9 (increasing 19.1 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 111.9. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 15.6). Three hour interval K indices: 11011155 (planetary), 11012245 (Boulder).

The background x-ray flux was at the class B4 level.

At the time of counting spots (see image time) spots were observed in 9 active regions in 2K resolution (SN: 159) and 8 active regions in 1K resolution (SN: 114) SDO images on the visible solar disk.

Region 11856 [N07W09] was quiet and stable.
Region 11857 [S07W10] was quiet and stable.
Region 11860 [S27E28] was quiet and stable.
Region 11861 [S11E48] developed slowly and was quiet. The region has minor polarity intermixing.
Region 11862 [S22W35] was quiet and stable.
New region 11863 [S17E20] emerged on October 6 and was numbered 2 days later by SWPC.
New region 11864 [S22E68] rotated into view on October 7 and was numbered by SWPC the next day. This is a complex region with a significant magnetic delta structure in the trailing spot section. Further M class flaring is possible. The region produced an M2.8 flare at 01:48 UTC on October 9. Note that SWPC has split this region into two with the trailing part as AR 11865.

Spotted regions not numbered by SWPC:
S2729 [S15W48] reemerged with a few spots.
New region S2740 [N05E18] emerged with penumbra spots.

An interesting chain of events started at the northeast limb near 08:30 UTC as a filament became active. The activity spread along the filament channel to near the center of the visible disk and then in a southeasterly direction along a filament channel in the southern hemisphere. A filament eruption was observed late in the day, however, it is too early to tell if an interesting CME was launched.

Coronal mass ejections (CMEs)

October 6: A faint full halo CME was observed in LASCO imagery after 15h UTC, the source of the CME was likely an eruption near the central meridian in the southern hemisphere at 13:45 UTC.
October 7-8: 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 recurrent coronal hole (CH589) in the northern hemisphere was in an Earth facing position on October 5-8. A recurrent trans equatorial coronal hole (CH590) could rotate into an Earth facing position on October 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 very poor. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to minor storm on October 9 due to CME effects and quiet to active on October 10 due to effects from CH589 becoming quiet to unsettled on October 11.

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
11854	2013.09.27 2013.09.28				N05W84						plage location: N07W72
11857	2013.10.01 2013.10.02	1	3	1	S08W11	0090	HSX	CSO			area: 0190 location: S07W10
11856	2013.10.01 2013.10.02	3	20	7	N07W10	0030	CAO	DRO
S2729	2013.10.02		3	2	S15W48	0012		BXO
11859	2013.10.02 2013.10.04				S15W65						plage
S2732	2013.10.03				S25W02						plage
11862	2013.10.03 2013.10.07	3	6	4	S23W34	0020	CSO	HRX
S2734	2013.10.04				N24W33						plage
11861	2013.10.06 2013.10.07	3	12	6	S13E50	0010	BXO	ERO			location: S11E48 area: 0050
11860	2013.10.06 2013.10.07	2	3	3	S27E31	0010	AXX	HRX
11863	2013.10.06 2013.10.08	4	9	4	S18E19	0010	BXO	CRO
11864	2013.10.07 2013.10.08	1	11	7	S23E62	0050	HSX	EAC			beta-gamma-delta area: 0320 location: S22E68
11865	2013.10.08	2			S20E73	0060	CAO				part of AR 11864
S2739	2013.10.07				N17W16						plage
S2740	2013.10.08		2		N05E18	0004		BXO
Total spot count:		19	69	34
Sunspot number:		99	159	114	(total spot count + 10 * number of spotted regions)
Weighted SN:		44	94	59	(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):		59	56	63	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.