Solar Terrestrial Activity Report

Last major update issued on November 1, 2013 at 05:55 UTC.

[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 31. Solar wind speed at SOHO ranged between 335 and 560 km/s. Another weak CME based disturbance began after 17h UTC, likely the result of activity observed on October 28.

Solar flux measured at 20h UTC on 2.8 GHz was 142.6 (increasing 33.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 117.9. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.1). Three hour interval K indices: 21122212 (planetary), 10112322 (Boulder).

The background x-ray flux is at the class B8 level.

At the time of counting spots (see image time) spots were observed in 11 active regions in 2K resolution (SN: 259) and 10 active regions in 1K resolution (SN: 167) SDO images on the visible solar disk.

Region 11879 [S12W81] decayed slowly and quietly.
Region 11881 [S23W60] reemerged with a few spots.
Region 11882 [S11W19] decayed slowly and quietly.
Region 11884 [S15E14] has many spots spread out over a large area. Most of the spots are in the northern central part. The region has polarity intermixing and a weak magnetic delta structure. M flares are possible.
Region 11886 [N15W34] decayed slowly and quietly.
Region 11887 [N20E50] decayed slowly and quietly.
New region 11888 [S16W32] emerged on October 27 and was numbered by SWPC 4 days later.

Spotted regions not numbered by SWPC:
S2789 [N02W21] was quiet and stable. The new leader spot may belong to a separate region.
S2792 [S10W59] was quiet and stable.
New region S2793 [N19W13] emerged with a penumbra spot.
New region S2796 [N05E71] emerged with a penumbra spot.
New region S2797 [S08E08] emerged with penumbra spots.

AR 11877 produced an M1.9 flare from behind the southwest limb at 13:51 UTC.

Coronal mass ejections (CMEs)

October 29-30: An asymmetric full halo CME was observed after the X2 flare in AR 11875 at the west limb late on Oct.29 and early on Oct.30. The CME could reach Earth on November 1-2.
October 31: No obviously Earth directed CMEs were observed in LASCO or 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 coronal hole (CH592) will rotate into an Earth facing positon on October 31-November 3. The coronal hole takes on a narrow and elongated shape in its western section.

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 to good.

Forecast

The geomagnetic field is expected to be quiet to unsettled on November 1-2 due to CME effects. Quiet to unsettled is likely on November 3-5 due to effects from CH592.

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
11879	2013.10.21	2	1	1	S12W83	0080	HSX	HAX
11881	2013.10.22 2013.10.24		2	1	S22W62	0018		CRO			plage
11882	2013.10.23 2013.10.24	14	33	11	S10W19	0190	DAO	DSO
S2780	2013.10.24				S10W45						plage
S2781	2013.10.25				N26W30						plage
11883	2013.10.26				N04E03						plage location: N02E06
11884	2013.10.26	23	68	33	S12E12	0370	EKC	EKC			beta-gamma-delta area: 0600 location: S15E14
11885	2013.10.26	6			S18E12	0180	CSO				part of AR 11884
11888	2013.10.27 2013.10.31	4	21	9	S15W32	0020	CRO	DRI
S2786	2013.10.27				N07W48						plage
11886	2013.10.28 2013.10.29	5	7	2	N14W36	0030	CSO	BXO
S2789	2013.10.29		2	2	N02W21	0010		BXO
11887	2013.10.29 2013.10.30	4	9	5	N21E48	0030	CSO	CRO			location: N20E50
S2791	2013.10.29				N13W18						plage
S2792	2013.10.30		2	1	S10E59	0007		BXO
S2793	2013.10.30				N19W26						plage
S2794	2013.10.30				S12E42						plage
S2796	2013.10.31		1		N05E71	0001		AXX
S2797	2013.10.31		3	2	S08E08	0012		AXX
Total spot count:		58	149	67
Sunspot number:		128	259	167	(total spot count + 10 * number of spotted regions)
Weighted SN:		96	178	96	(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):		77	91	92	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.