Solar Terrestrial Activity Report

Last major update issued on October 29, 2012 at 05:15 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 28. Solar wind speed at SOHO ranged between 284 and 378 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 117.0 (decreasing 11.1 over the last solar rotation). 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: 01211011 (planetary), 00222210 (Boulder).

The background x-ray flux was at the class B3 level.

At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).

Region 11596 [N07W64] decayed slowly and quietly.
Region 11598 [S12W23] decayed slowly and quietly.
Region 11599 [S12E04] was quiet and stable.
Region 11600 [N08W38] developed slowly and was quiet.

Spotted regions not numbered by NOAA/SWPC:
S2010 [S13E22] was quiet and stable.
S2015 [S25W16] was quiet and stable.
New region S2016 [S20E79] rotated into view.
New region S2017 [N18W03] emerged with tiny spots.
New region S2018 [S18W63] emerged with a tiny spot.
New region S2019 [N10E18] emerged with a tiny spot.

Coronal mass ejections (CMEs)

October 26, 28: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
October 27: A sequence of filament eruptions across the equator near AR 11600 began at about 14h UTC and reached its most intense level 2 hours later. A CME was observed in STEREO-B at 16:25 UTC and in STEREO-B when imagery resumed a couple of hours later. This CME is likely to have Earth directed components and could reach Earth on October 30.

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 poorly defined coronal hole (CH543) in the northern hemisphere will likely rotate into an Earth facing position on October 30-31. A recurrent coronal hole (CH544) in the southern hemisphere will likely be in an Earth facing position on November 1.

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 29. A CME could cause unsettled to minor storm conditions on October 30-31.

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
11596	2012.10.17 2012.10.18	5	6	4	N06W65	0150	DAO	HAX			area: 0280
11598	2012.10.20	7	12	9	S11W23	0240	DAC	DHO			area: 0380
11599	2012.10.22 2012.10.23	1	6	2	S11E04	0060	HSX	HSX			area: 0170
S2007	2012.10.22				S33W53						plage
11600	2012.10.24 2012.10.26	2	7	3	N09W42	0010	AXX	CRO
S2010	2012.10.25		4	1	S13E22	0000		AXX
S2012	2012.10.25				S09W56						plage
S2014	2012.10.27				S02W16
S2015	2012.10.27		3		S24W05	0000		BXO
S2016	2012.10.28		1	1	S20E79	0040		HRX
S2017	2012.10.28		2	1	N18W03	0000		AXX
S2018	2012.10.28		1		S18W63	0000		AXX
S2019	2012.10.28		1		N10E18	0000		AXX
Total spot count:		15	43	21
Sunspot number:		55	143	91	(total spot count + 10 * number of spotted regions)
Weighted SN:		30	69	47	(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):		33	50	50	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.