Solar Terrestrial Activity Report

Last major update issued on October 16, 2012 at 05:35 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 quiet to active on October 15. Solar wind speed at SOHO ranged between 379 and 537 km/s under the decreasing influence of a high speed stream from CH539.

Solar flux measured at 20h UTC on 2.8 GHz was 136.8 (increasing 32.5 over the last solar rotation). The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.4). Three hour interval K indices: 43221022 (planetary), 33322221 (Boulder).

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

At midnight UTC the visible solar disk had 12 spotted active regions (in 2K resolution SDO images).

Region 11586 [S13W41] decayed slowly and quietly.
Region 11589 [N12W05] decayed losing spots and penumbral area. No mature penumbra was observed.
Region 11590 [S30E07] decayed slowly and quietly.
Region 11591 [N07E33] decayed slowly in the trailing polarity area while small spots emerged in the leading polarity. C class flaring is still likely.
Region 11592  [N22E07] decayed slowly and quietly.
New region 11593 [N16E76] rotated into view.
New region 11594 [S28E63] rotated into view on October 14 and was numbered the next day by SWPC.

Spotted regions not numbered by NOAA/SWPC:
S1977 [S14W15] developed slightly and was quiet.
New region S1986 [N22E37] emerged with a tiny spot.
New region S1987 [N08E72] rotated into view with a tiny spot.
New region S1988 [S15E17] emerged with a tiny spot.
New region S1989 [S25W05] emerged with a tiny spot.

Coronal mass ejections (CMEs)

October 13-15: 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 (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 good.

Forecast

The geomagnetic field is expected to be initially quiet on October 16. A high speed stream from CH541 could produce a few unsettled and active intervals late on October 16 and on October 17. Quiet to unsettled conditions are likely on October 18.

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	1	1	1	S13W36	0060	HSX	HSX			location: S13W41
S1967	2012.10.08				N14W53						plage
11589	2012.10.09	27	43	24	N14W06	0130	DRI	DRI			beta-gamma location: N12W05
11590	2012.10.10 2012.10.11	1	9	4	S30E05	0030	HRX	CRO
S1974	2012.10.10				S09W56						plage
11591	2012.10.11 2012.10.12	12	26	11	N07E32	0230	DSO	CSI			beta-gamma area: 0330
S1977	2012.10.11		2	1	S14W15	0005		AXX
11592	2012.10.12 2012.10.14	5	5	1	N23E06	0010	BXO	CRO
S1979	2012.10.12				S24W44						plage
S1980	2012.10.12				N13W45						plage
11594	2012.10.14 2012.10.15	2	12	5	S26E61	0030	DRO	DRO			location: S28E63
S1984	2012.10.14				N03W00						plage
S1985	2012.10.14				N05W24						plage
11593	2012.10.15	1	2	2	N17E78	0060	HSX	CAO			location: N16E76
S1986	2012.10.15		1		N22E37	0000		AXX
S1987	2012.10.15		1		N08E72	0000		AXX
S1988	2012.10.15		1		S15E17	0000		AXX
S1989	2012.10.15		1		S25W05	0000		AXX
Total spot count:		49	104	49
Sunspot number:		119	224	129	(total spot count + 10 * number of spotted regions)
Weighted SN:		73	131	76	(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):		71	78	71	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.