Solar Terrestrial Activity Report

Last major update issued on October 15, 2012 at 06:35 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 unsettled to minor storm on October 14. Solar wind speed at SOHO ranged between 466 and 570 km/s under the influence of a high speed stream from CH539.

Solar flux measured at 20h UTC on 2.8 GHz was 132.1 (increasing 30.6 over the last solar rotation). The Potsdam WDC planetary A index was 25 (STAR Ap - based on the mean of three hour interval ap indices: 25.4). Three hour interval K indices: 53344344 (planetary), 53443222 (Boulder).

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

At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).

Region 11586 [S12W27] was quiet and stable.
Region 11589 [N13E08] has many small spots, a small total umbral area with mostly low contrast penumbra. There's a slight chance of a minor M class flare.
Region 11590 [S29E20] decayed slowly and quietly.
Region 11591 [N07E48] developed significantly forming a small magnetic delta structure in a trailing penumbra. A minor M class flare is possible.
New region 11592  [N24E22] emerged on October 12 and was numbered 2 days later by SWPC. Slow development was observed on Oct.14.

Spotted regions not numbered by NOAA/SWPC:
S1977 [S16E03] reemerged with tiny spots.
New region S1983 [S26E78] rotated into view with 2 spots.
New region S1984 [N03E13] emerged with a tiny spot.
New region S1985 [N05W11] emerged with tiny spots.

Coronal mass ejections (CMEs)

October 12-14: 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 southern hemisphere coronal hole (CH539) was in an Earth facing position on October 9-11. A  northern hemisphere coronal hole (CH541) was Earth facing on October 13.

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 poor. Propagation on long distance northeast-southwest paths is fair.

Forecast

The geomagnetic field is expected to be quiet to active on October 15 due to a high speed stream from CH539. A high speed stream from CH541 could produce a few unsettled and active intervals on October 16-17.

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
11586	2012.10.06 2012.10.07	2	3	1	S13W28	0070	HSX	CSO
S1967	2012.10.08				N14W40						plage
11589	2012.10.09	34	65	32	N13E09	0240	EAC	DAC			beta-gamma
11590	2012.10.10 2012.10.11	1	7	3	S30E17	0040	HSX	CAO
S1974	2012.10.10				S09W43						plage
11591	2012.10.11 2012.10.12	5	12	10	N07E45	0220	DSI	DSC			beta-gamma-delta area: 0320
S1977	2012.10.11		2		S16E03	0000		AXX
11592	2012.10.12 2012.10.14	5	10	6	N23E20	0020	DRO	DRI
S1979	2012.10.12				S24W31						plage
S1980	2012.10.12				N13W32						plage
S1982	2012.10.13				N16W53						plage
S1983	2012.10.14		2	2	S26E78	0020		HRX
S1984	2012.10.14		1		N03E13	0000		AXX
S1985	2012.10.14		2	1	N05W11	0000		BXO
Total spot count:		47	104	55
Sunspot number:		97	194	125	(total spot count + 10 * number of spotted regions)
Weighted SN:		70	130	81	(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):		58	68	69	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.