Solar Terrestrial Activity Report

Last major update issued on October 23, 2012 at 03:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-24 (last update October 3, 2012)] [Cycle 24 progress (last update October 1, 2012) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update October 3, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update October 3, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update October 1, 2012)]

[POES auroral activity level since October 2009 - updated October 7, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet on October 22. Solar wind speed at SOHO ranged between 345 and 390 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 155.5 (increasing 7.6 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: 3.3). Three hour interval K indices: 21100111 (planetary), 10001210 (Boulder).

The background x-ray flux was at the class B6 level.

At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).

Region 11591 [N07W62] was quiet and stable.
Region 11593 [N15W18] decayed slowly and quietly.
Region 11594 [S30W27] was quiet and stable.
Region 11596 [N07E18] displayed no significant changes and remains capable of producing an M class event.
Region 11598 [S12E57] has a strong magnetic delta structure in the large trailing penumbra. Further M class flaring is likely. Flares: C6.3 at 16:03, major M5.0/1F at 18:51 UTC as well as a few small C class events. The region was the source of a major X1.8 flare at 03:17 UTC on October 23.

Spotted regions not numbered by NOAA/SWPC:
S2000 [N12W26] decayed slowly and quietly.
S2001 [S20W17] was quiet and stable.
S2004 [N18E07] was quiet and stable.
New region S2006 [S11E85] rotated into view with a single spot.
New region S2007 [S35E35] emerged with a tiny spot.
New region S2008 [N04W05] emerged with a tiny spot.

Coronal mass ejections (CMEs)

October 20-22: 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 northern hemisphere coronal hole (CH542) was in an Earth facing position on October 17-18.

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

Forecast

The geomagnetic field is expected to be quiet on October 23-25.

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 higher resolution image) 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
11590	2012.10.10 2012.10.11				S31W81						plage
11591	2012.10.11 2012.10.12	1	1	1	N06W61	0100	HSX	HSX			area: 0200
11594	2012.10.14 2012.10.15		6	2	S27W31	0000		BXO
11593	2012.10.15	4	9	4	N14W18	0020	CRO	CRO
S1986	2012.10.15				N22W54						plage
S1987	2012.10.15				N08W19						plage
11596	2012.10.17 2012.10.18	31	29	16	N07E20	0310	DKI	EKI			area: 0500
S1992	2012.10.17				S16W42						plage
11597	2012.10.17 2012.10.18				S22W83						plage
S1997	2012.10.18				N07W19						plage
S1998	2012.10.18				S16W54						plage
S2000	2012.10.19		4	1	N12W26	0000		BXO
S2001	2012.10.19		3	1	S20W17	0000		AXX
11598	2012.10.20	10	17	11	S10E56	0370	DHI	DKC			beta-gamma-delta area: 0650 location: S12E57
S2002	2012.10.20				S18W49						plage
S2003	2012.10.21				N09E43						plage
S2004	2012.10.21		1	1	N20E07	0000		AXX
S2005	2012.10.21				N09E09						plage
S2006	2012.10.22		1	1	N09E22	0150		HSX
S2007	2012.10.22		1	1	S35E35	0000		AXX
S2008	2012.10.22		1		N04W05	0000		AXX
Total spot count:		46	73	39
Sunspot number:		86	183	139	(total spot count + 10 * number of spotted regions)
Weighted SN:		74	106	72	(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):		52	64	76	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.