Solar Terrestrial Activity Report

Last major update issued on June 8, 2012 at 04:50 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)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update May 3, 2012)]

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

Recent activity

The geomagnetic field was quiet to unsettled on June 7. Solar wind speed at SOHO ranged between 560 and 722 km/s under the influence of a high speed stream from CH520.

Solar flux measured at 20h UTC on 2.8 GHz was 128.2 (decreasing 8.2 over the last solar rotation). The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.0). Three hour interval K indices: 22222233 (planetary), 22132222 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).

Region 11493 [N15W36] was quiet and stable.
Region 11494 [S16W18] developed slowly with closely spaced opposite polarity spots to th south and southwest of the large penumbra. An M class flare is possible.
Region 11497 [S21W43] lost penumbral area in the largest penumbrae, however, some growth was observed in the southern parts of the region with some polarity intermixing occurring.
Region 11498 [N08E04] decayed slowly and quietly.
Region 11499 [N16E07] decayed losing quite a few small spots. AR 11496 was merged into this region. The region produced the only notable flare of the day, a C9.1/2N at 15:43 UTC.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1703 [N13W28] decayed slowly and quietly.
S1713 [N11E19] was quiet and stable.
S1714 [N27W62] developed slowly and quietly.
New region S1715 [S26E67] rotated into view at the southeast limb.

Coronal mass ejections (CMEs)

June 5: A filament eruption near AR 11493 and close to the central meridian was observed beginning at 19:30 UTC. A small CME was observed at 20:39 UTC in STEREO-A.
June 6: A partial halo CME associated with an M2 flare in AR 11494 was observed from 20:39 UTC in LASCO images. This CME could reach Earth late on June 9 or early on June 10.
June 7: 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 large recurrent trans equatorial coronal hole (CH520) was in an Earth facing position on June 1-4.

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 June 8 due to effects from CH520. The CME observed on June 6 could reach Earth late on June 9 or early on June 10 and cause unsettled to active conditions with a chance of minor storming.

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
11495	2012.05.27 2012.05.31				S15W74						plage
11494	2012.05.30 2012.05.31	5	18	8	S18W19	0120	DSO	DHO			beta-gamma area: 0310
11493	2012.05.30 2012.05.31	9	8	4	N15W33	0100	EAI	CSO			beta-gamma location: N15W36
11496	2012.05.30 2012.06.01	1			N16W24	0020	HAX				merged with AR 11499
11497	2012.05.30 2012.06.01	5	15	10	S21W44	0170	DAI	DAO
11498	2012.05.31 2012.06.01	4	6	1	N06W11	0050	CAO	CRO			location: N08W11 area: 0020
S1703	2012.06.01		15	9	N13W28	0030		CRI			SWPC thinks this is part of AR 11493
11499	2012.06.01 2012.06.03	14	37	16	N15W09	0020	CAI	CSO
11502	2012.06.02 2012.06.04				S17W02						plage
11500	2012.06.02 2012.06.04				N09W77						plage
11501	2012.06.04				N07W30						plage
S1709	2012.06.04				N13E11						plage
11503	2012.06.04 2012.06.05				N09W69						plage
S1713	2012.06.06		3		N11E19	0000		BXO
S1714	2012.06.06		4	2	N27W62	0010		CRO
S1715	2012.06.07		1	1	S26E67	0000		AXX
Total spot count:		38	107	51
Sunspot number:		98	197	131	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		68	141	85	(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):		59	69	72	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.