Solar Terrestrial Activity Report

Last major update issued on March 7, 2012 at 05:25 UTC. Minor update posted at 15:50 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 6. Solar wind speed at SOHO ranged between 336 and 386 km/s. A brief and sudden increase in solar wind density was observed at SOHO at 13:24 UTC as well as a minor abrupt increase in solar wind speed. On March 7 near 03:30 UTC a significant solar wind shock was observed at ACE. Since then the interplanetary magnetic field has been strongly southwards. It is currently uncertain if this shock was related to the CME observed on March 4 or the one on March 5. Major geomagnetic storming is likely over the next hours.

Solar flux measured at 20h UTC on 2.8 GHz was 138.1 (increasing 40.9 over the last solar rotation). The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.4). Three hour interval K indices: 32302223 (planetary), 32413322 (Boulder).

The background x-ray flux is at the class C1 level.

At midnight UTC the visible solar disk had 8 spotted active regions (in 2K resolution SDO images).

Region 11424 [N08W73] was quiet and stable.
Region 11428 [S17E08] had most spots merge into two penumbrae during the first half of the day, then small intermediate spots began to emerge late in the day. The region has a small magnetic delta structure near the northern edge of the trailing penumbra. A minor M class flare is possible.
Region 11429 [N17E28] extended longitudinally and has a very strong magnetic delta structure across most of the central part of the huge penumbra. Further X class flares are likely over the next days. Flares: M1.3 at 00:28, M1.2 at 01:44, C2.4 at 02:33, C9.2 at 03:28, M1.0/1N at 04:05, C2.9 at 05:28, C5.3 at 07:43, M1.0 at 07:55, C2.8 at 11:17, M2.1/1N at 12:41, M1.3 at 21:11, M1.0 at 22:53 UTC. On March 7 the region has produced 2 X flares: X5.4/3B (associated with a fast, wide CME) at 00:24 and X1.3 at 01:14 (associated with a fast, but still significantly slower CME than the one observed less than an hour before) UTC. The latter X flare occurred in the western part of the magnetic delta structure while the X5 event was near the center of the inversion line. A radiation storm was associated with these events and is currently in progress.
Region 11430 [N20E13] developed further and still has weak polarity intermixing in the central spot section.
Region 11431 [S27W49] decayed slowly and quietly.

Spotted regions not reported by NOAA/SWPC:
[S1498] reemerged on March 6. Location at midnight: N32W60
[S1500] reemerged on March 6. Location at midnight: N10W13
[S1512] emerged in the southeast quadrant on March 5. Location at midnight: S18E35

Minor update added at 15:50 UTC: The CME observed on March 5 arrived near 13h UTC (estimated time based on available data) and caused an increase to severe geomagnetic storm levels. The planetary A index for the 12-15h UTC interval was 111 (Kp 7; note that this is based on the traditional estimates of geomagnetic activity. SWPC introduced another estimate using a different set of observing magnetometers earlier this year. The new set typically has lower Kp than the magnetometers normally used. In this case Kp 6 for the same time interval). Ap was 94 for the 06-09h UTC interval and 80 for the next 3-hour interval.

Region 11429 has been mostly quiet after the 2 X flares. The region is still very complex and could produce further X class flares. The radiation storm is intensifying with the above 10 MeV proton flux currently above 1700 pfu. The peak could be significantly higher when the huge CME observed today reaches Earth tomorrow.

Only 4 active regions had spots at 14:45 UTC, see the most recent high resolution CHARMAP.

Coronal mass ejections (CMEs)

March 4: The long duration M2 event in region 11429 was associated with a full halo CME which could reach Earth on March 6 or early on March 7.
March 5: Another full halo CME was observed after the X1 event. The CME could reach Earth on March 7.
March 6: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
March 7: The X flares in region 11429 produced fall halo CMEs that could reach Earth sometime on March 8 and cause active to very severe geomagnetic storming.

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 recurrent, elongated coronal hole (CH506) in the southern hemisphere was in an Earth facing position on March 3-4.

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

Forecast

The geomagnetic field is expected to be unsettled to major storm due to CME effects on March 7. Active to severe storm is possibly on March 8-9 due to the CMEs observed early on March 7.

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
11423	2012.02.22 2012.02.23	1			N18W90	0030	HSX				rotated out of view
11424	2012.02.24		1		N08W73	0000		AXX
S1498	2012.02.28		2		N32W60	0010		CRO
S1500	2012.02.29		1		N10W13	0000		AXX
11427	2012.02.29 2012.03.01				N15W73						plage
S1503	2012.03.01				N12W45						plage
S1504	2012.03.01				N10W49						plage
S1505	2012.03.02				S27W01						plage
11428	2012.03.02 2012.03.03	17	27	13	S16E09	0250	DAI	DSI			beta-gamma-delta area: 0450
11429	2012.03.02 2012.03.03	25	47	22	N17E29	1120	DKC	EKC			beta-gamma-delta area: 1700 reversed polarities
S1509	2012.03.03				S10W13						plage
11430	2012.03.04	11	27	17	N19E13	0110	DAO	DAI			beta-gamma
11431	2012.03.04 2012.03.05	5	5	4	S28W48	0030	DRO	BXO
S1512	2012.03.05		3	1	S18E35	0000		AXX
Total spot count:		59	113	57
Sunspot number:		109	193	107	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		87	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):		65	68	59	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.