Solar Terrestrial Activity Report

Last major update issued on February 14, 2013 at 05:00 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update February 1, 2013)] [Cycle 24 progress (last update February 2, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 3, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated February 3, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to active on February 13. Solar wind speed at SOHO ranged between 308 and 381 km/s under the influence of a weak to moderate disturbance.

Solar flux measured at 20h UTC on 2.8 GHz was 100.3 (decreasing 22.4 over the last solar rotation). The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.4). Three hour interval K indices: 33111134 (planetary), 22111234 (Boulder).

The background x-ray flux was at the class B1 level.

At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).

Region 11670 [N18W55] was mostly quiet and stable.
Region 11671 [N15E34] gained a few penumbra spots.
Region 11672 [S17E13] decayed slowly and quietly.

Spotted regions not numbered by SWPC:
S2213 [N15W28] was quiet and stable.
S2226 [S07W28] was quiet and stable.
S2228 [S07E25] decayed slowly and quietly.
New region S2230 [N18W43] emerged with a penumbra spot.
New region S2231 [S33E02] emerged with a penumbra spot.
New region S2232 [N28W10] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

February 11-13: 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 small coronal hole (CH554) in the southern hemisphere rotated across the central meridian on February 12.

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 fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on February 14 and quiet on February 15. On February 16 there is a chance of a few unsettled intervals due to effects from CH554.

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 2K resolution) Compare to the previous day's image. 0.5k image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue 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
11669	2013.02.04 2013.02.05				N07W59						plage
11670	2013.02.05 2013.02.07	5	12	6	N17W55	0110	DSO	DSI
S2213	2013.02.08		2		N15W28	0004		AXX
S2216	2013.02.09				S18E10						plage
11672	2013.02.10 2013.02.11		1	1	S18E12	0005		AXX
11671	2013.02.10 2013.02.11	1	6	2	N14E31	0100	HSX	HSX			location: N15E34 area: 0160
S2219	2013.02.10				S32W56						plage
S2222	2013.02.11				N30E35						plage
S2225	2013.02.11				N31W53						plage
S2226	2013.02.11		1		S07W28	0002		AXX
S2227	2013.02.12				N14E25						plage
S2228	2013.02.12		2	1	S07E25	0007		AXX
S2229	2013.02.12				S02W35						plage
S2230	2013.02.13		1		N18W43	0003		AXX
S2231	2013.02.13		1		S33E02	0002		AXX
S2232	2013.02.13		1		N15W43	0003		AXX
Total spot count:		6	27	10
Sunspot number:		26	117	50	(total spot count + 10 * number of spotted regions)
Weighted SN:		16	37	20	(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):		16	41	28	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 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) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive 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.