Solar Terrestrial Activity Report

Last major update issued on March 8, 2012 at 05:10 UTC. Minor update posted at 13:50 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 unsettled to severe storm on March 7. Solar wind speed at SOHO ranged between 344 and 578 km/s. Two CMEs arrived during the day. The full halo CME observed on March 4 caused a solar wind shock at SOHO at 03:27 UTC. The interplanetary magnetic field swung strongly southwards and caused minor to major geomagnetic storm conditions until the arrival of the next CME. The full halo CME observed on March 5 arrived at SOHO at 12:01 UTC. This CME intensified geomagnetic storming to severe storm levels.

Solar flux measured at 20h UTC on 2.8 GHz was 135.7 (increasing 36.5 over the last solar rotation). The planetary A index was 64 (STAR Ap - based on the mean of three hour interval ap indices: 63.9). Three hour interval K indices: 35667744 (planetary), 35666533 (Boulder).

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

At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).

Region 11428 [S17W04] lost a few spots and still has slight polarity intermixing. A minor M class flare is possible. The region finally produced a flare early on March 8 (C7.2 at 02:53 UTC)
Region 11429 [N17E16] extended longitudinally with a northeastern penumbra splitting off from the huge penumbra. That penumbra is currently nearly 10 degrees wide and contains multiple magnetic delta structures. Further X class flares are possible. Flares: X5.4/3B at 00:24 and X1.3 at 01:14 (wrongly attributed to region 11430 by SWPC) UTC. Both X class events were associated with huge, wide and fast full halo CMEs. Mass ejection continued for many hours after the initial eruption. The SDO/EVE image below displays the intensity of the X1.3 flare. Notice that the circular area nearly fully overlaps the weakening emissions from the X5.4 flare.

Region 11430 [N20W00] developed in the leading spot section. There is still weak polarity intermixing.
Region 11431 [S27W62] decayed slowly and quietly.

Spotted regions not reported by NOAA/SWPC:
[S1512] emerged in the southeast quadrant on March 5. Location at midnight: S17E23
[S1513] emerged in the southeast quadrant on March 7. Location at midnight: S22E46
[S1514] emerged in the northeast quadrant on March 7. Location at midnight: N12E37

Minor update added at 11:05 UTC: The expected CME reached ACE near 10:40 UTC and should impact Earth within minutes. Initially the interplanetary magnetic field is very strong and mostly northwards.

Minor update added at 13:50 UTC: The geomagnetic field has so far been at minor storm levels. The total IMF field has weakened considerably since the previous update with few and mostly weak southernly excursions. Otherwise region 11429 is decaying with the main penumbra fragmenting further.

Coronal mass ejections (CMEs)

March 5: Another full halo CME was observed after the X1 event. The CME reached 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 full halo CMEs that could reach Earth before noon 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.

Forecast

The geomagnetic field is expected to be unsettled to very severe storm on March 8 and unsettled to severe storm on March 9 due to CME effects. Quiet to unsettled is likely on March 10 (assuming there are no further flares in region 11429).

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
S1500	2012.02.29				N10W26						plage
11427	2012.02.29 2012.03.01				N15W87						plage
S1503	2012.03.01				N12W58						plage
S1505	2012.03.02				S27W14						plage
11428	2012.03.02 2012.03.03	16	22	14	S17W05	0300	DKO	DKO			beta-gamma area: 0400
11429	2012.03.02 2012.03.03	28	54	22	N17E15	1270	DKC	EKC			beta-gamma-delta area: 1700 reversed polarities
S1509	2012.03.03				S10W26						plage
11430	2012.03.04	16	23	13	N21W00	0200	DAI	DKI			beta-gamma
11431	2012.03.04 2012.03.05	2	3	2	S24W64	0030	DSO	CRO			location: S27W62 area: 0010
S1512	2012.03.05		2	1	S17E23	0000		AXX
S1513	2012.03.07		1	1	S22E46	0000		AXX
S1514	2012.03.07		3	2	N12E37	0000		BXO
Total spot count:		62	108	55
Sunspot number:		102	178	125	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		92	141	88	(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):		61	62	69	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.