Solar Terrestrial Activity Report

Last major update issued on June 6, 2012 at 05:15 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 unsettled to active on June 5. Solar wind speed at SOHO ranged between 603 and 840 km/s under the influence of a high speed stream from CH520.

Solar flux measured at 20h UTC on 2.8 GHz was 138.7 (increasing 11.4 over the last solar rotation). The Potsdam WDC planetary A index was 22 (STAR Ap - based on the mean of three hour interval ap indices: 21.6). Three hour interval K indices: 34434344 (planetary), 34324333 (Boulder).

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

At midnight UTC the visible solar disk had 15 spotted active regions (in 2K resolution SDO images).

Region 11492 [S13W70] reemerged with two small spots.
Region 11493 [N13W08] developed polarity intermixing and remained quiet.
Region 11494 [S19E07] developed further with a new penumbra forming to the south of the large penumbra. This new penumbra contains both polarity spots and there is a chance of a minor M class flare.
Region 11495 [S15W44] decayed slowly and quietly.
Region 11496 [N13E06] decayed slowly and could merge into AR 11499.
Region 11497 [S22W18] matured with umbrae merging inside the two major penumbrae.
Region 11498 [N05E16] developed slowly and could become an interesting region with the poorly defined inversion line in a mostly east-west direction.
Region 11499 [N13E19] developed further adding many tiny spots. The region is the most active on the disk despite no mature penumbra on any spots. There's polarity intermixing and a chance of an M class flare.
Region 11500 [N08W47] decayed slowly and quietly
Region 11502 [S19E27] decayed slowly and quietly.
New region 11503 [N10W37] emerged on June 4 and was numbered by SWPC one day later.

Spotted active regions not numbered by NOAA/SWPC:
S1703 [N11W03] was quiet and stable
S1709 [N13E37] was quiet and stable.
S1711 [S18W75] developed slowly and quietly.
New region S1712 [N01W60] emerged near the equator with a single spot.

Coronal mass ejections (CMEs)

June 3-4: No obviously Earth directed CMEs were observed in LASCO or STEREO imagery.
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.

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 good.

Forecast

The geomagnetic field is expected to be quiet to active on June 6 and quiet to unsettled on June 7-8 due to effects from CH520. There's a slight chance of weak effects from the CME observed on June 5 late on June 8 or early on June 9.

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
11492	2012.05.24 2012.05.25	1	2	1	S18W73	0010	AXX	AXX			location: S13W70 note that SWPC data is for AR S1711 as they lost track of AR 11492
11495	2012.05.27 2012.05.31		3	1	S15W46	0000		AXX			location: S15W44
S1693	2012.05.28				S20W57						plage
11494	2012.05.30 2012.05.31	9	21	10	S17E06	0160	CSO	DHI			beta-gamma-delta area: 0320 location: S19E07
11493	2012.05.30 2012.05.31	12	7	6	N12W05	0170	EAI	DSO			beta-gamma location: N13W08
11496	2012.05.30 2012.06.01	2	9	3	N17E06	0030	CSO	CSO			location: N13E06
11497	2012.05.30 2012.06.01	8	19	9	S21W18	0170	DAO	DAO			area: 0360
11498	2012.05.31 2012.06.01	8	15	10	N07E16	0070	DAO	DRI			location: N05E16
S1702	2012.05.31				S27W58						plage
S1703	2012.06.01		16	7	N11W03	0100		DSI			SWPC thinks this is part of AR 11493
11499	2012.06.01 2012.06.03	10	53	19	N15E18	0030	ERO	CRI			location: N13E19
11502	2012.06.02 2012.06.04	1	1	1	S17E27	0000	AXX	AXX
11500	2012.06.02 2012.06.04	1	3	1	N09W49	0020	HSX	HRX
S1708	2012.06.03				N25W36						plage
11501	2012.06.04				N07W00						plage
S1709	2012.06.04		1		N13E37	0000		AXX
11503	2012.06.04 2012.06.05	2	6	4	N11W38	0010	BXO	CRO
S1711	2012.06.04		4	2	S18W75	0030		CRO
S1712	2012.06.05		1	1	N01W70	0000		AXX
Total spot count:		54	161	75
Sunspot number:		154	311	215	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		87	206	120	(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):		92	109	118	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.