Solar Terrestrial Activity Report

Last major update issued on July 9, 2012 at 06:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-24 (last update June 2, 2012)] [Cycle 24 progress NEW]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 2, 2012)]
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[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 1, 2012)]

[POES auroral activity level since October 2009 - updated July 2, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to minor storm on July 8. Solar wind speed at SOHO ranged between 395 and 541 km/s. The total field of the interplanetary magnetic field strengthened significantly after 08:30 UTC. Bz was mostly northwards until 22h UTC, then swung moderately southwards causing a active to minor storm conditions at the end of the day. The source of this disturbance is likely a CME, perhaps the one associated with the X1 flare on July 6.

Solar flux measured at 20h UTC on 2.8 GHz was 177.7 (increasing 43.8 over the last solar rotation). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.5). Three hour interval K indices: 22232225 (planetary), 23232323 (Boulder).

The background x-ray flux is at the class C3 level.

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

Region 11515 [S17W79] rotated partly out of view, however, the largest penumbra split into smaller penumbrae with none of the visible penumbra exceeding 2.5 degrees latitudinal extent. The region continued to produce lots of C and M flares and could produce another major event while at or just behind the southwest limb. Flares: C6.6 at 04:19, C5.9 at 05:34, M1.3 at 05:46, C6.8/1F at 06:25, M1.1/1F at 09:53, C6.9 at 10:30, C5.4 at 10:50, M1.4/1F at 12:10, C6.7 at 14:43, major M6.9/1N at 16:32 UTC.
Region 11518 [N09E13] decayed slowly and quietly.
Region 11519 [S16E23] was quiet and stable.
Region 11520 [S17E48] is a large and compact region with a huge main penumbra. There's a significant magnetic delta structure in the central part of this penumbra. A major flare is possible. Flares: C6.1 at 13:02, C8.8 at 17:43, C6.6 at 19:24 UTC

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1776 [S16E38] developed quickly and could produce minor M class flares.
S1777 [S12E45] was quiet and stable.
S1781 [S16E28] developed slowly with polarity intermixing. Flare: C9.2 at 18:03 UTC.
S1782 [S21E35] developed slowly and quietly.
S1783 [N15E37] was quiet and stable.
S1785 [S25E18] added a few tiny spots.
New region S1786 [S20W51] emerged to the west of AR S1780.
New region S1787 [S20E05] emerged with a tiny spot.

Coronal mass ejections (CMEs)

July 6: While the core CME associated with the X1 event in AR 11515 will not reach Earth, a flank impact is likely on July 9.
July 7-8: 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 coronal hole (CH522] in the northern hemisphere was in an Earth facing position on July 6-7. 

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 fair.

Forecast

The geomagnetic field is expected to be quiet to minor storm on July 9-10 due to CME and coronal hole effects. Quiet to active is likely on July 11.

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

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
11513	2012.06.25 2012.06.26	3			N17W89	0180	HSX				rotated out of view
11515	2012.06.26 2012.06.27	32	19	12	S17W76	0550	EKI	EAC			location: S17W79
11516	2012.06.27 2012.06.29				N20W79						plage location: N14W78
11517	2012.06.30 2012.07.01				N19W67
S1769	2012.07.01				N17W47						plage
11518	2012.07.03 2012.07.04	3	12	5	N10E12	0030	DSO	BXO			location: N09E13 area: 0010
11519	2012.07.04	1	6	2	S15E22	0080	HSX	CSO
S1774	2012.07.04				S26E25						plage
11520	2012.07.05 2012.07.06	23	62	26	S15E43	1070	FHC	EKC			beta-gamma-delta location: S17E48 area: 1600
S1776	2012.07.05		35	19	S16E38	0140		DAI
S1777	2012.07.05		2	1	S12E45	0100		HSX
S1778	2012.07.05				S28W52						plage
S1779	2012.07.05				N15W36						plage
S1780	2012.07.06				S21W46						plage
S1781	2012.07.07		10	5	S16E28	0040		DRO			beta-gamma
S1782	2012.07.07		9	4	S21E35	0030		CRO
S1783	2012.07.07		2		N13E37	0000		AXX
S1784	2012.07.07				N25W10						plage
S1785	2012.07.07		7	2	S25E18	0000		AXX
S1786	2012.07.08		1	1	S20W51	0000		AXX
S1787	2012.07.08		1		S20E05	0000		AXX
Total spot count:		62	165	77
Sunspot number:		112	285	177	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		97	201	113	(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	100	97	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) 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) Month average to date.
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.