Solar Terrestrial Activity Report

Last major update issued on March 1, 2012 at 04:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update February 2, 2012)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 5, 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 February 29. Solar wind speed ranged between 376 and 488 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 102.0 (decreasing 16.0 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.4). Three hour interval K indices: 32200011 (planetary), 23201211 (Boulder).

The background x-ray flux is at the class B2 level.

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

Region 11423 [N17W08] was quiet and stable.
Region 11425 [N22W21 decayed slowly and quietly.
Region 11426 [N11W34] decayed slowly and was quiet.

Spotted regions not reported by NOAA/SWPC:
[S1489] reemerged on February 29. Location at midnight: S15W59
[S1496] emerged in the northeast quadrant on February 27, developed slowly on Feb.28, then decayed on Feb.29. Location at midnight: N10E13
[S1500] emerged in the northeast quadrant on February 29. Location at midnight: N10E64
[S1501] emerged in the northeast quadrant on February 29. Location at midnight: N17E13
[S1502] emerged in the southwest quadrant on February 29. Location at midnight: S18W18

Coronal mass ejections (CMEs)

February 27-29: 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 recurrent coronal hole (CH503) in the northern hemisphere was in an Earth facing position on February 26-27. A coronal hole (CH505) in the southern hemisphere will rotate into an Earth facing position on Feb.29-March 1.

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

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 1-2 due to effects from CH503 and quiet to unsettled on March 3-4 as CH505 becomes geoeffective.

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
S1489	2012.02.22		2	1	S15W59			BXO
S1490	2012.02.22				S20W41						plage
11423	2012.02.22 2012.02.23	1	4	1	N17W09	0120	HSX	CSO			area: 0200
11425	2012.02.23 2012.02.26		1		N22W21	0000		AXX
11424	2012.02.24				N07W00						plage
S1494	2012.02.24				N15E05						plage
S1495	2012.02.25				S20W25						plage
11426	2012.02.26	1	2	2	N11W31	0010	AXX	AXX			location: N11W34
S1496	2012.02.27		3		N10E13	0000		BXO
S1497	2012.02.27				N07W09	0000		AXX			plage
S1498	2012.02.28				N33E18						plage
S1499	2012.02.28				S18W38						plage
S1500	2012.02.29		1		N10E64	0000		AXX
S1501	2012.02.29		5	2	N17E13	0010		BXO
S1502	2012.02.29		2	1	S18W18	0000		AXX
Total spot count:		2	20	7
Sunspot number:		22	100	57	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		7	25	12	(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):		13	45		k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1, 2011) for STAR SDO 2K

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.