Solar Terrestrial Activity Report

Last major update issued on March 3, 2012 at 05:05 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 unsettled on March 2. Solar wind speed ranged between 359 and 461 km/s under the influence of a high speed stream from CH503. Early on March 3 another high speed stream (from CH505) has become the dominant solar wind source.

Solar flux measured at 20h UTC on 2.8 GHz was 108.2 (increasing 1.2 over the last solar rotation). The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.4). Three hour interval K indices: 33313122 (planetary), 33313222 (Boulder).

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

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

Region 11423 [N16W34] was quiet and stable.
Region 11427 [N15W15] lost some spots, however, opposite polarity spots are currently observed within the small penumbra. C flares are possible.

Spotted regions not reported by NOAA/SWPC:
[S1504] emerged in the northeast quadrant on March 1. Location at midnight: N12E03
[S1505] emerged in the southeast quadrant on March 2. Location at midnight: S27E51
[S1506] emerged in the southeast quadrant on March 2. Location at midnight: S17E67
[S1507] rotated partly into view at the northeast limb on March 2 revealing a huge penumbra with a latitudinal extent in excess of 5 degrees. The region could produce further M class flares, even an X flare is possible. Flare: M3.3 at 17:46 UTC. The flare was associated with a CME off the east limb.
[S1508] emerged in the southwest quadrant on March 2. Location at midnight: S18W18

Coronal mass ejections (CMEs)

February 29-March 2: 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 coronal hole (CH505) in the southern hemisphere was in an Earth facing position on Feb.29-March 1. A recurrent, elongated coronal hole (CH506) in the southern hemisphere will likely rotate into 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 active on March 3 due to effects from CH505, becoming quiet to unsettled on March 4 and quiet on March 5. On March 6-8 a high speed stream from CH506 could cause quiet to unsettled conditions with occasional active intervals.

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	3	2	N17W36	0080	HSX	CSO			area: 0150 location: N16W34
11425	2012.02.23 2012.02.26				N22W47						plage
11424	2012.02.24				N07W26						plage
S1494	2012.02.24				N15W21						plage
S1495	2012.02.25				S20W51						plage
11426	2012.02.26				N11W59						plage
S1496	2012.02.27				N10W13						plage
S1497	2012.02.27				N07W35						plage
S1498	2012.02.28				N33W08						plage
S1500	2012.02.29				N10E38						plage
11427	2012.02.29 2012.03.01	3	6	3	N15W16	0020	CRO	DAO			beta-delta area: 0050
S1502	2012.02.29				S27W42						plage
S1503	2012.03.01				N12E07						plage
S1504	2012.03.01		2	1	N12E03	0010		AXX
S1505	2012.03.02		3		S27E51	0000		BXO
S1506	2012.03.02		1		S17E67	0000		AXX
S1507	2012.03.02		2	2	N17E85	1050		HHX
S1508	2012.03.02		5	2	S18W18	0010		BXO
Total spot count:		4	22	10
Sunspot number:		24	92	60	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		12	42	30	(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):		14	32	33	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.