Solar Terrestrial Activity Report

Last major update issued on October 23, 2013 at 06:40 UTC. Updates are likely to be irregular or very late until October 25.

[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 October 9, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated October 10, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet on October 22. Solar wind speed at SOHO ranged between 280 and 408 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 146.3 (increasing 35.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 114.0. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.8). Three hour interval K indices: 00210112 (planetary), 01222222 (Boulder).

The background x-ray flux was at the class C1 level.

At the time of counting spots (see image time) spots were observed in 12 active regions in 2K resolution (SN: 314) and 11 active regions in 1K resolution (SN: 206) SDO images on the visible solar disk.

Region 11872 [S17W24] was quiet and stable.
Region 11873 [N11W18] was quiet and stable.
Region 11874 [S12W47] decayed slowly and quietly.
Region 11875  [N06E03] developed further and has become a large compact and magnetically complex region capable of producing major flares, even X class events. There are two significant magnetic delta structures. C5+ flares: M1.0 at 00:22, M1.0 long duration event peaking at 15:20, M4.2/1B at 21:20 UTC. The M4 flare was associated with a small CME which could be Earth directed.
Region 11877 [S12E25] developed in the leading spot section with a small penumbra forming to the north of the major penumbra. Both polarities are present with umbrae in that penumbra. An M class flare is possible.
Region 11879 [S12E38] was split off from AR 11877 as the trailing polarity fields of both regions separated.
Region 11880 [N12W29] decayed slowly and quietly.

Spotted regions not numbered by SWPC:
S2769 [N15W01] was quiet and stable.
New region S2774 [S19W29] emerged early in the day.
New region S2775 [S22E65] emerged near the southeast limb.
New region S2776 [N10E53] emerged with penumbra spots in an old plage area.
New region S2777 [N35E32] emerged at a high latitude.

A filament eruption near AR S2769 was observed beginning early on October 22. A partial halo CME was observed after 04h UTC.

Coronal mass ejections (CMEs)

October 20-21: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
October 22: A partial CME was observed early in the day following a filament eruption in the northeast quadrant. A small CME appears to be associated with the M4 event in AR 11875 late in the day.

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

No obvious coronal holes are currently in or near Earth facing positions.

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 to good. Propagation on long distance northeast-southwest paths is fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on October 23-24. October 25 could see the arrival of CMEs. If any of the CMEs arrive unsettled to active conditions will be likely with a chance of minor storm intervals.

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
11868	2013.10.11 2013.10.13				N23W72						actual location: N17W71, SWPC has moved this region to the location of AR S2764
11869	2013.10.12 2013.10.13				N16W42						plage location: N20W56
S2753	2013.10.13				N17W39						plage
11871	2013.10.14				N16W48						plage
11872	2013.10.14 2013.10.15	4	4	2	S17W26	0060	CAO	HAX			area: 0090
11873	2013.10.14 2013.10.16	4	10	7	N12W17	0010	AXX	BXO
11878	2013.10.14 2013.10.20				S09W81						plage
11874	2013.10.16 2013.10.17	13	4	1	S11W47	0030	DRO	BXO			area: 0008
11875	2013.10.16 2013.10.17	123	107	50	N07E04	0420	EKC	EKC			beta-gamma-delta area: 1000 location: N06E03
S2767	2013.10.17				S05W12						plage
11877	2013.10.18	15	40	20	S13E23	0390	DKI	DKI			beta-gamma-delta area: 0500 location: S12E25
S2769	2013.10.18		4	1	N15W01	0010		BXO
S2770	2013.10.18				S22W46						plage
11879	2013.10.21	9	11	9	S13E37	0080	CSO	CAO			split off from AR 11877 area: 0130
11880	2013.10.21		2	1	N12W30	0010		BXO
S2774	2013.10.22		5	2	S19W29	0030		CRO
S2775	2013.10.22		4	2	S22E65	0015		CRO
S2776	2013.10.22		2		N10E33	0006		AXX
S2777	2013.10.22		1	1	N35E32	0005		AXX
Total spot count:		168	194	96
Sunspot number:		228	314	206	(total spot count + 10 * number of spotted regions)
Weighted SN:		201	230	132	(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):		137	110	113	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.