Solar Terrestrial Activity Report

Last major update issued on March 23, 2012 at 05:35 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 21, 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 active on March 22. Solar wind speed at SOHO ranged between 345 and 442 km/s. A minor disturbance was observed arriving at ACE near 18h UTC and caused unsettled to active conditions for the remainder of the day and early on March 23.

Solar flux measured at 20h UTC on 2.8 GHz was 102.4 (decreasing 6.5 over the last solar rotation). The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.6). Three hour interval K indices: 12110134 (planetary), 11001233 (Boulder).

The background x-ray flux is undetermined (the main data source for x-ray flux, GOES-15, is unavailable. SWPC is using GOES-13 to monitor x-ray flux).

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

Region 11433 [N09W82] decayed slowly and quietly.
Region 11438 [S14E44] was quiet and stable.
Region 11440 [S26W38] decayed and currently has a magnetically simple structure.
New region 11441 [S28W56] emerged in the southwest quadrant on March 19 and was numbered by SWPC 3 days later.
New region 11442 [N12E52] emerged in the northeast quadrant on March 21 and got an SWPC number one day later.
New region 11443 [N16E65] rotated into view at the northeast limb on March 21 and was assigned a number by SWPC the following day.

Spotted regions not reported by NOAA/SWPC:
[S1543] emerged in the northeast quadrant on March 22. Location at midnight: N20E52
[S1544] emerged in the northeast quadrant on March 22. Location at midnight: N23E14

An active region is early on March 23 rotating into view at the southeast limb (S23E86) with several spots. The region could produce C flares.

Coronal mass ejections (CMEs)

March 20-22: 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 (CH508) in the southern hemisphere was in an Earth facing position on March 20. CH508 decayed and had closed on March 22 due to new corona from AR 11440. A very elongated recurrent trans equatorial coronal hole (CH509) will rotate into an Earth facing position on March 23-26.

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 poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 23-24 and quiet on March 25. A high speed stream from CH509 could cause quiet to active conditions on March 26-29.

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
11433	2012.03.10 2012.03.11	1	1	1	N09W81	0010	AXX	AXX
11436	2012.03.15 2012.03.16				S14W20						plage
11437	2012.03.16 2012.03.17				S34W55						plage
S1533	2012.03.18				N23W03						plage
S1534	2012.03.18				N13W13						plage
11438	2012.03.19 2012.03.20	2	5	3	S15E43	0060	HSX	HSX
11440	2012.03.19 2012.03.21	8	8	4	S25W38	0030	DRO	CRO
11441	2012.03.19 2012.03.22	1	4	2	S27W57	0010	AXX	BXO
S1539	2012.03.20				N05W01						plage
11442	2012.03.21 2012.03.22	1	3	1	N13E49	0010	AXX	BXO			location: N12E52
11443	2012.03.21 2012.03.22	1	1	1	N16E65	0010	AXX	HRX
S1542	2012.03.21				S17W45						plage
S1543	2012.03.22		4	3	N20E52	0020		CRO
S1544	2012.03.22		7	5	N23E14	0020		CRO
Total spot count:		14	33	20
Sunspot number:		74	113	100	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		22	50	37	(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):		44	40	55	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 quicklook Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.