Solar Terrestrial Activity Report

Last major update issued on March 7, 2011 at 05:05 UTC. Minor update posted at 20:10 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, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update March 2, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update March 2, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update March 1, 2011)]

[POES auroral activity level charts since October 2009 - updated March 4, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2105 [Dec-Jan.2011] - 2106 [Jan.-Feb.2011] NEW

The geomagnetic field was quiet to unsettled on March 6.

Solar flux measured at 20h UTC on 2.8 GHz was 142.5 (increasing 60.2 over the last solar rotation and a new high for cycle 24). The planetary A index  was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.9). Three hour interval K indices: 11003122 (planetary), 01003222 (Boulder).

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

At midnight UTC the visible solar disk had 7 spotted regions.

Region 11164 developed further during the first half of the day with new flux emerging in the central parts of the region, then began to decay. What used to be the largest penumbra lost more than half of its area as several spots split off. The central penumbra is large, highly asymmetrical and has a magnetic delta structure. A major flare is still possible. Flares: C1.8 at 01:33, C1.8 at 04:15, C1.7 at 04:44, C4.6 at 05:32, C2.8 at 07:07, C2.4 at 07:33, C3.1 at 10:01, C4.7 at 16:19, C6.9 at 16:30, C2.3 at 19:37 UTC.
Region 11165 did not change significantly and was quiet. Observe that NOAA/SWPC has included S891 in this region.
Region 11166 decayed slowly and has only minor polarity intermixing.  Flares: C5.1 at 12:09, C3.9 at 15:27 UTC
Region 11167 was quiet and stable.
New region 11169 rotated into view at the northeast limb on March 5 and was numbered the next day by NOAA/SWPC. The region developed slowly on March 6. Flare: C6.0 at 13:50 UTC

Spotted regions not numbered by NOAA/SWPC:
[S891] This region emerged in the southwest quadrant on March 3 and developed slowly the first days. Rapid development was observed on March 6 with many new spots emerging and at least 2 magnetic delta structures forming. M class flares are possible in this compact region.  Location at midnight: S17W69. Flares: C2.1 at 02:08, C3.7 at 03:45, C1.6 at 08:33, C2.6 at 09:04, C7.5 at 10:40, C1.4 at 21:57, C2.2 at 23:35 UTC.
[S896] Spots emerged in the northeast quadrant, just north of region 11166, on March 6. Location at midnight: N16E22.

Minor update added at 20:10 UTC on March 7: A total of 5 minor M class flares had been observed until 19:30 UTC, 3 from region 11164, 1 from S891 and the only event of real interest, a long duration M1.9 event in region 11166 peaking at 14:30 UTC. This event was associated with type II and IV radio sweeps and an Earth directed CME. The CME could reach Earth late on March 9 or on March 10. Otherwise region S891 has continued its amazing growth with most spots now inside a single very elongated penumbra. This region has the potential to produce a major proton event, possibly even an X class event. Two new spotted regions are visible. The latest coronal hole and active region map.

The largest flare of the day is in progress as this is written and seems to be peaking near the class M4 level. Solar flux at 17h UTC was 151.9.

March 4-6: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

No significant coronal holes are currently in or near an Earth facing position.

The darkest areas on the solar disk are likely coronal holes.

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 poor.

The geomagnetic field is expected to be quiet to unsettled on March 7 due to effects from the CME observed on March 3, with a chance of some active intervals. On March 8-9 quiet conditions are likely.

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 polarity overlay		Comment
		SWPC	STAR SDO			SWPC	STAR	Current	Previous
11163	2011.02.24			N17W65						location: N16W51
11164	2011.02.25	25	52	N24W46	0640	EKC	EKC			beta-gamma-delta
11165	2011.02.26 2011.02.25	21	13	S20W68	0200	EAO	CRI			location: S23W63 area: 0030 SWPC has included S891 in this region
11166	2011.03.02	16	28	N11E27	0360	EKC	EHC			beta-gamma location: N09E27
11167	2011.03.02 2011.03.03	2	8	N09W09	0020	BXO	BXO			location: N14W06
S891	2011.03.03		45	S17W69	0300		EAC			beta-gamma-delta
S893	2011.03.03			N20W17						plage
11169	2011.03.05 2011.03.06	4	13	N21E56	0030	BXO	CRI			formerly region S894 location: N19E58
S895	2011.03.05			N07W01						plage
S896	2011.03.06		5	N16E27	0020		CRO
Total spot count:		68	164
Sunspot number:		118	234

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.