Solar Terrestrial Activity Report

Last major update issued on September 5, 2014 at 04:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update September 1, 2014)] [Cycle 24 progress (last update September 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update September 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update September 1, 2014)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update August 9, 2014)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated July 18, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet to unsettled on September 4. Solar wind speed at SOHO ranged between 354 and 414 km/s.

Solar flux at 20h UTC on 2.8 GHz was 146 (increasing 23 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 133.5. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.9). Three hour interval K indices: 32221111 (planetary), 22243321 (Boulder).

The background x-ray flux is at the class B9 level.

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 219) and 9 active regions using 1K resolution (SN: 139) SDO images on the visible solar disk.

Region 12152 [S14W38] decayed slowly producing a few C flares.
Region 12153 [S10W65] matured and was mostly quiet.
Region 12154 [S18E09] was quiet and stable.
Region 12155 [S20E61] was quiet and stable.
New region 12156 [N15E57] emerged on September 3 and was numbered the next day by SWPC.
New region 12157 [S12E73] rotated fully into view revealing a large and complex region capable of producing a major flare.
New region 12158 [N15E80] rotated into view with a large penumbra. A major flare is possible.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3776 [N10W12] was quiet and stable.
S3781 [S07E21] reemerged with penumbra spots.
S3786 [S22W11] was quiet and stable.
S3791 [N18E35] reemerged with penumbra spots.
New region S3796 [N08E13] emerged with penumbra spots.

C2+ Flares (GOES):

Coronal mass ejections (CMEs)

September 3-4: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
September 2: A filament eruption, mainly in the northwest quadrant and with extensions into the southwest and northeast quadrant was observed from approximately 16h UTC. A partial halo CME was observed later in LASCO 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 trans equatorial extension of a northern hemisphere coronal hole (CH634) will rotate into an Earth facing position on September 5.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on September 5-6 with a chance of active intervals if the CME observed on September 2 reaches Earth. On September 7 quiet conditions are likely.

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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% 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	Magnetic (SDO)				SWPC	STAR	Current	Previous
			2K	1K
12151	2014.08.22 2014.08.23	2			S08W88	0060	HAX				rotated out of view
12153	2014.08.26 2014.08.29	9	10	5	S09W65	0190	DAI	DAO			area: 0310
12152	2014.08.26 2014.08.28	16	24	13	S15W38	0310	EKI	EAO			beta-gamma area: 0290
S3772	2014.08.29				S07W50						plage
S3774	2014.08.29				N05W49						plage
S3776	2014.08.30		3	1	N10W12	0008		BXO
S3779	2014.08.30				N10W32						plage
S3781	2014.08.31		2		S07E21			BXO
S3782	2014.08.31				N24W28						plage
12154	2014.09.01 2014.09.02	10	21	11	S18E09	0020	CRI	DRI			area: 0060
S3784	2014.09.01				S28W28						plage
S3786	2014.09.02		1		S23W22	0002		AXX
S3787	2014.09.02				N45E22						plage
S3788	2014.09.02				S31W09						plage
S3791	2014.09.03		3		N18E35			AXX
12155	2014.09.03	3	10	4	S20E59	0170	DAO	CAO			area: 0410
12157	2014.09.03 2014.09.04	12	16	8	S13E68	0200	DAI	EKC			beta-gamma-delta area: 0600 location: S12E73
12156	2014.09.03 2014.09.04	2	3	3	N15E56	0010	BXO	CRO
12158	2014.09.04	2	4	3	N16E83	0100	HAX	CKO			area: 0380 location: N15E80
S3796	2014.09.04		2	1	N08E13	0008		BXO
Total spot count:		56	99	49
Sunspot number:		136	219	139	(total spot count + 10 * number of spotted regions)
Weighted SN:		94	140	90	(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):		62	65	79	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

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 WDC-SILSO 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 GFZ 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.