Solar Terrestrial Activity Report

Last major update issued on March 5, 2012 at 07:20 UTC. Minor update posted at 17:30 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 February 27, 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 minor storm on March 4. Solar wind speed at SOHO ranged between 342 and 386 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 120.1 (increasing 17.9 over the last solar rotation). The planetary A index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 13.6). Three hour interval K indices: 53331232 (planetary), 43322232 (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 11423 [N16W60] was quiet and stable.
Region 11427 [N15W43] decayed slowly and was mostly quiet. Flare: C2.7 at 17:31 UTC
Region 11428 [S17E36] developed further and has at least C class flare potential. The region has a small magnetic delta structure in a trailing penumbra.
Region 11429 [N17E56] developed and is a compact and complex region capable of producing major (proton) flares. The huge penumbra has an unusually large and strong magnetic delta structure. Flares: C1.4 at 01:45, C2.8 at 03:33, C1.3 at 06:51, M2.0/1N long duration event peaking at 10:52 UTC. The latter event was associated with a wide CME and a minor increase in proton flux levels. The region produced a major X1.1 long duration event peaking at 04:09 on March 5.
New region 11430 [N19E38] emerged quickly in the northeast quadrant and could produce C flares.

Spotted regions not reported by NOAA/SWPC:
[S1498] reemerged on March 4. Location at midnight: N32W33
[S1504] emerged in the northeast quadrant on March 1. Location at midnight: N10W23
[S1511] emerged fairly quickly in the southwest quadrant on March 4. Location at midnight: S28W22

Minor update added at 17:30 UTC: Region 11429 appears to be preparing for another major flare. The magnetic delta structure shows no signs of weakening, on the contrary, umbrae near the inversion line are bigger and more numerous. See this image:

Region 11428 is developing as well and could produce a minor M class flare:

The latest high resolution CHARMAP

Coronal mass ejections (CMEs)

March 2-3: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
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 early on March 5.

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 poor. Propagation on long distance northeast-southwest paths is good.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 5. Sometime on March 6 or early on March 7 could see the arrival of the CME observed on March 4 and could cause unsettled to minor storm conditions. The March 5 CME could arrive late on March 6 or on March 7 and cause unsettled to major storm conditions.

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	1	1	N17W61	0070	HSX	HSX			area: 0130 location: N16W60
11424	2012.02.24				N07W52						plage
S1494	2012.02.24				N15W47						plage
11426	2012.02.26				N11W87						plage
S1496	2012.02.27				N10W39						plage
S1498	2012.02.28		6	4	N32W33	0010		BXO
S1500	2012.02.29				N10E12						plage
11427	2012.02.29 2012.03.01	2	4	2	N15W45	0010	BXO	BXO			location: N15W43
S1503	2012.03.01				N12W19						plage
S1504	2012.03.01		2		N10W23	0000		BXO
S1505	2012.03.02				S27E25						plage
11428	2012.03.02 2012.03.03	6	21	11	S17E37	0070	DSO	DAI			beta-gamma-delta area: 0220
11429	2012.03.02 2012.03.03	8	32	15	N18E55	0700	DKC	DKC			beta-gamma-delta area: 1200
S1508	2012.03.02				S18W44						plage
S1509	2012.03.03				S10W00						plage
11430	2012.03.04	3	11	5	N19E40	0020	CRO	DAI			beta-gamma location: N19E38 area: 0100
S1511	2012.03.04		11	6	S28W22	0040		CAI
Total spot count:		20	88	44
Sunspot number:		70	168	114	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		43	118	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):		42	59	63	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.