Solar Terrestrial Activity Report

Last major update issued on June 5, 2012 at 05:05 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 minor storm on June 4. Solar wind speed at SOHO ranged between 324 and 664 km/s. A high speed stream from cH520 became the dominant solar wind source after 04h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 128.2 (increasing 5.4 over the last solar rotation). The Potsdam WDC planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 18.9). Three hour interval K indices: 23354334 (planetary), 23354323 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight UTC the visible solar disk had 14 spotted active regions (in 2K resolution SDO images).

Region 11493 [N14E06] lost the trailing penumbra to AR S1703 with new trailing spot emerging closer to the leading penumbra.
Region 11494 [S18E20] added several small spots in both polarities to the west and south of the single penumbra. Minor polarity intermixing is currently observed.
Region 11495 [S15W33] decayed slowly and quietly.
Region 11496 [N14E19] was mostly quiet and stable.
Region 11497 [S23W05] was quiet and stable.
Region 11498 [N06E29] was quiet and stable.
Region 11499 [N13E33] added many tiny spots and was quiet.
New region 11500 [S09W32] emerged on June 2 and was numbered by SWPC 2 days later.
New region 11501 [N03E15] emerged with a few small spots.
New region 11502 [S19E41] emerged on June 2 and was assigned a number by SWPC 2 days later.

Spotted active regions not numbered by NOAA/SWPC:
S1703 [N11E12] developed slowly and was quiet.
New region S1709 [N13E49] emerged with a single spot.
New region S1710 [N10W23] emerged near CH520 with a few spots.
New region S1711 [S19W61] emerged with two small spots.

Coronal mass ejections (CMEs)

June 2-4: 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 to good.

Forecast

The geomagnetic field is expected to be quiet to active on June 5-6 with a chance of minor storm intervals due to effects from CH520. Quiet to unsettled is likely on June 7-8.

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				S14W58						plage location: S13W62
11495	2012.05.27 2012.05.31	4	5	2	S15W32	0010	AXX	BXO
S1693	2012.05.28				S20W44						plage
S1694	2012.05.28				N09W59						plage
11494	2012.05.30 2012.05.31	2	16	7	S16E18	0120	CSO	CSO			area: 0210 location: S18E20
11493	2012.05.30 2012.05.31	10	8	5	N13E08	0180	ESI	DSO			location: N14E06
11496	2012.05.30 2012.06.01	8	9	4	N17E17	0050	CSO	CSO			location: N14E19
11497	2012.05.30 2012.06.01	19	26	15	S21W06	0150	DAO	DAI			area: 0320 location: S23W05
11498	2012.05.31 2012.06.01	2	10	6	N09E29	0020	HSX	CRI			location: N06E29
S1702	2012.05.31				S27W45						plage
S1703	2012.06.01		20	11	N11E12	0100		DSO			SWPC thinks this is part of AR 11493
11499	2012.06.01 2012.06.03	2	31	11	N15E34	0040	CRO	CRI			location: N13E33
11502	2012.06.02 2012.06.04	2	2	2	S17E41	0010	BXO	AXX			No polarity analysis by SWPC?
11500	2012.06.02 2012.06.04	4	5	3	N09W34	0030	DRO	CRO
S1708	2012.06.03				N25W23						plage
11501	2012.06.04	2	3	1	N07E15	0000	AXX	BXO
S1709	2012.06.04		1		N13E49	0000		AXX
S1710	2012.06.04		4	3	N10W23	0010		CRO
S1711	2012.06.04		2		S19W61	0000		AXX
Total spot count:		55	142	70
Sunspot number:		155	282	190	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		86	179	107	(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):		93	99	105	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.