Solar Terrestrial Activity Report

Last major update issued on August 26, 2014 at 04:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update August 1, 2014)] [Cycle 24 progress (last update August 13, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update August 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update August 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 very quiet on August 25. Solar wind speed at SOHO ranged between 276 and 307 km/s.

Solar flux at 20h UTC on 2.8 GHz was 135 (decreasing 6.6 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 131.3. The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.1). Three hour interval K indices: 00011101 (planetary), 00002321 (Boulder).

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

At the time of counting spots (see image time), spots were observed in 8 active regions using 2K resolution (SN: 173) and 7 active regions using 1K resolution (SN: 113) SDO images on the visible solar disk.

Region 12146 [N08W43] developed slowly and is a compact and complex region capable of producing a major flare.
Region 12147 [S10W34] was quiet and stable.
Region 12148 [N07W28] decayed slowly and quietly.
Region 12149 [N10E19] developed in the leading spot section while there was little change in the central and trailing spot section. The region has polarity intermixing and could produce a minor M class flare.
Region 12150 [S13E35] was quiet and stable.
Region 12151 [S07E60] was mostly quiet and unchanged.

Spotted regions not numbered (or interpreted differently) by SWPC:
New region S3763 [N13W07] emerged early in the day as a bipolar region, then decayed slowly and had only a single penumbra spot left by the end of the day.
New region S3764 [N03E39] was observed with penumbra spots.

C2+ Flares (GOES):

Coronal mass ejections (CMEs)

August 23: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
August 24: A wide CME was observed after the M5 event in AR 12151. While the core of the CME wasn't Earth directed, there is a slight chance of a solar wind shock on August 27.
August 25: A full halo CME was observed after the M2 flare in AR 12146. The CME will likely reach Earth on August 28.

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 (CH632) will likely rotate into an Earth facing position on August 27-28.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet on August 26-27. On August 28 a CME will likely arrive and could cause unsettled to minor storm conditions that day and on August 29. A high speed stream from CH632 could arrive on August 30 and cause quiet to active conditions.

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
12143	2014.08.13 2014.08.14	2			S03W92	0010	AXX				rotated out of view
12141	2014.08.13 2014.08.14	1			N17W88	0010	AXX				rotated out of view
12146	2014.08.16	11	22	12	N09W46	0290	DKI	DKC			beta-delta location: N08W43 area: 0480
12147	2014.08.17		2	1	S08W38	0007		BXO			location: S10W34
S3746	2014.08.18				N20W49						plage
S3747	2014.08.18				N13W53						plage
12148	2014.08.19 2014.08.20	11	18	6	N07W26	0060	CAO	CRO
12149	2014.08.21	14	36	18	N10E21	0190	EAI	EKI			beta-gamma location: N10E19 area: 0340
12150	2014.08.22	1	5	2	S14E34	0110	CSO	CAO			area: 0200
12151	2014.08.22 2014.08.23	2	7	3	S08E47	0140	CSO	CAO			area: 0210
S3759	2014.08.23				N13W47						plage
S3760	2014.08.23				S16W29						plage
S3761	2014.08.23				S42W31						plage
S3762	2014.08.24				N18W46						plage
S3763	2014.08.25		1	1	N13E07	0004		AXX
S3764	2014.08.25		2		N03E39	0005		AXX
Total spot count:		42	93	43
Sunspot number:		112	173	113	(total spot count + 10 * number of spotted regions)
Weighted SN:		72	126	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):		67	61	62	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.