Solar Terrestrial Activity Report

Last major update issued on March 12, 2012 at 05:40 UTC. Minor update posted at 09:00 UTC

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

[POES auroral activity level since October 2009 - updated March 5, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2118 [December 2011 - January 2012] - 2119 [January-February 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on March 11. Solar wind speed at SOHO ranged between 358 and 472 km/s. The CME observed on March 9 arrived later than expected and was observed reaching SOHO at 12:50 UTC with a minor abrupt increase in solar wind speed and density. The associated disturbance was much weaker than anticipated.

Solar flux measured at 20h UTC on 2.8 GHz was 131.2 (increasing 22.8 over the last solar rotation). The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.9). Three hour interval K indices: 22122333 (planetary), 22132322 (Boulder).

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

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

Region 11428 [S15W59] decayed quickly and lost all trailing spots.
Region 11429 [N18W37] decayed significantly losing small spots and some penumbral area. The leading opposite polarity penumbrae drifted apart again. There's still a magnetic delta structure in the central spot region, however, none of the umbrae are large and overall there is significantly less magnetic complexity compared to a few days ago. There's still a chance of another major flare.
Region 11430 [N21W55] decayed quickly and lost all trailing spots.
Region 11432 [N15E40] added a few spots and was mostly quiet.
New region 11433 [N12E64] rotated into view at the northeast limb on March 10 with SWPC numbering it a day later.
New region 11434 [S22E57] emerged near the southeast limb on March 10 and got an SWPC number the next day.

Spotted regions not reported by NOAA/SWPC:
[S1505] reemerged on March 9. Location at midnight: S26W70
[S1517] emerged in the southeast quadrant on March 9. Location at midnight: S25W07
[S1524] emerged in the southeast quadrant on March 11. Location at midnight: S25E45

Minor update added at 09:00 UTC: A strong solar wind shock was observed at ACE near 08:40 UTC. The interplanetary magnetic field is initially strongly southwards and this is likely to cause at least major geomagnetic storming, perhaps severe storming. The shock is associated with the CME observed on March 10.

Coronal mass ejections (CMEs)

March 9: The M6 event in region 11429 produced a full halo CME. This CME reached Earth on March 11
March 10: The M8 event in region 11429 was associated with an inpressive halo CME which is likely to reach Earth on March 12.
March 11: 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 large recurrent trans equatorial coronal hole (CH507) will rotate in an Earth facing position on March 13-14.

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 very poor. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to major storm on March 12-13 due to CME effects, severe storm intervals are possible. On March 14-15 quiet to unsettled conditions are likely. A high speed stream from CH507 could cause unsettled to minor storm conditions on March 16-17.

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
S1505	2012.03.02		1		S26W70	0000		AXX
11428	2012.03.02 2012.03.03	3	4	3	S15W60	0030	CAO	HRX
11429	2012.03.02 2012.03.03	22	41	20	N18W38	0840	EKC	EHC			beta-gamma-delta reversed polarities
11430	2012.03.04	6	4	3	N20W54	0100	CAO	HAX			area: 0050
S1512	2012.03.05				S23W17						plage
S1514	2012.03.07				N12W15						plage
11432	2012.03.08 2012.03.09	5	12	8	N16E40	0050	CAO	DRI
S1516	2012.03.08				N27W32						plage
S1517	2012.03.09		1		S25W07	0000		AXX
S1520	2012.03.09				N27W04						plage
S1521	2012.03.09				S32W55						plage
11434	2012.03.10 2012.03.11	4	9	4	S22E58	0090	DSO	DSO
11433	2012.03.10 2012.03.11	3	3	3	N12E63	0150	DSO	CSO			area: 0090
S1524	2012.03.11		3	2	S25E45	0010		BXO
Total spot count:		43	78	43
Sunspot number:		103	168	113	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		78	109	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):		62	59	62	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 preliminary daily SWPC ap indices. Values in red are based on the official NGDC 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.