Solar Terrestrial Activity Report

Last major update issued on August 6, 2012 at 05:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-24 (last update August 6, 2012)] [Cycle 24 progress (last update August 2, 2012) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update August 6, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update August 6, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update August 5, 2012)]

[POES auroral activity level since October 2009 - updated August 5, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on August 5. Solar wind speed at SOHO ranged between 293 and 373 km/s. A sudden and small increase in solar wind speed and density were observed near 02h UTC on August 6 at SOHO, probably the arrival of a weak CME transient.

Solar flux measured at 20h UTC on 2.8 GHz was 134.0 (decreasing 39.8 over the last solar rotation). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.9). Three hour interval K indices: 11111113 (planetary), 11122322 (Boulder).

The background x-ray flux is at the class B6 level.

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

Region 11532 [S19W66] decayed further with only a few small spots remaining outside of the single penumbra.
Region 11534 [N18W57] lost the trailing spots while new smal leader spots emerged.
Region 11535 [N18W16] was quiet and stable.
Region 11537 [N12E10] was quiet and stable.
Region 11538 [S23E06] has minor polarity intermixing and could produce C flares.
Region 11539 [S22E21] was quiet and stable.
Region 11540 [S27E32] developed with many small spots emerging. The region has polarity intermixing and could produce C and maybe minor M class flares.
Region 11541 [S15E37] gained several tiny spots and was quiet.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1842 [N18W03] was quiet and stable.
New region S1843 [N14E36] emerged with two tiny spots in an old plage area.
New region S1844 [N30E22] emerged with a small spot.
New region S1845 [N23W08] emerged near AR 11535.

An interesting region at the southeast limb has become quite active early on August 6. So far a C9 and an M1 flare have been recorded. Another interesting region is about to rotate into view at the northeast limb.

Coronal mass ejections (CMEs)

August 3, 5: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
August 4: A full halo CME was associated with a large filament eruption in the southeeast quadrant, the CME could influence Earth on August 7-9.

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 small trans equatorial coronal hole (CH536) will rotate into an Earth facing position on August 8.

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 unsettled on August 6. The CME from the August 4 eruption could reach Earth during the latter half of August 7 or early on August 8 and cause unsettled to minor storm conditions. Effects from CH526 are possible on August 11-12.

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
11530	2012.07.23 2012.07.24	1			S18W90	0120	HSX				rotated out of view
11532	2012.07.25 2012.07.26	1	5	3	S19W66	0210	HSX	CKO			area: 0260
11534	2012.07.27 2012.07.28		2		N23W54	0000		AXX			location: N18W57
11535	2012.07.29 2012.07.30	6	16	7	N18W15	0090	CSO	CSO			area: 0200
11536	2012.07.30				S25W52						part of AR 11532
11537	2012.07.31	1	1	1	N13E09	0040	HSX	HSX			area: 0090
11538	2012.07.31	8	21	10	S22E02	0140	DSO	DSO			beta-gamma area: 0310
S1835	2012.07.31				N12W29						plage
11539	2012.08.01 2012.08.02	1	7	3	S23E18	0010	HRX	CRO
S1837	2012.08.01				N27W20						plage
11541	2012.08.02 2012.08.03	1	10	1	S16E38	0000	AXX	BXO
11540	2012.08.02 2012.08.03	8	29	12	S27E32	0110	DSO	CAI			area: 0130
S1840	2012.08.02				N09W11						plage
S1842	2012.08.03		3	1	N18W03	0000		BXO
S1843	2012.08.05		2	1	N14E36	0000		AXX
S1844	2012.08.05		1	1	N30E22	0000		AXX
S1845	2012.08.05		1	1	N23W08	0000		AXX
Total spot count:		27	98	41
Sunspot number:		107	218	151	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		60	121	74	(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):		64	76	83	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) 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.