Solar Terrestrial Activity Report

Last major update issued on February 20, 2011 at 06:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
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[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
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[POES auroral activity level charts since October 2009]
Annotated geomagnetic activity charts - Carrington rotation 2104 [Nov-Dec.2010]- 2105 [Dec-Jan.2011] NEW

The geomagnetic field was quiet on February 19. Solar wind speed ranged between 390 and 577 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 109.4 (increasing 25.1 over the last solar rotation). The planetary A index  was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.1). Three hour interval K indices: 22211111 (planetary), 22312111 (Boulder).

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

At midnight UTC the visible solar disk had 5 spotted regions.

Region 11158 decayed slowly and has become less complex. There's still a chance of an M class flare. The region will be rotating over the southwest limb today. Flares: C1.3 at 01:37, C1.8 at 02:25, C1.9 at 07:44, C1.5 at 15:29, C1.9 at 16:30, C6.1 at 16:43, C1.9 at 21:13 UTC.
Region 11160 (SWPC duplicate number is 11161) developed slowly adding several spots. While there is polarity intermixing, no magnetic delta structures are visible. Flare: C3.4 at 03:03 UTC.
Region 11162 became much simpler magnetically resulting in a quick decrease in flare activity and intensity. Flares: C2.6 at 07:05, C8.5 at 08:04, C1.1 at 12:24, C1.0 at 14:53 UTC.

Spotted regions not numbered by NOAA/SWPC:
[S876] The region reemerged with a single tiny spot on February 19. Location at midnight: S17W33
[S878] This region emerged in the northeast quadrant on February 13 and has since then seen small spots coming and going. Location at midnight: N21W32

February 17-19: No obviously Earth directed CME 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 Earth facing positions.

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 be quiet on February 20-22.

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			SWPC	STAR	Current	Previous
11158	2011.02.11 2011.02.10	10	24	S19W78	0280	DKC	ESI			beta-gamma
S875	2011.02.10			N20W64						plage
S876	2011.02.11		1	S17W33	0000		AXX
11160	2011.02.12	19	42	N11W15	0250	EKC	FAI			beta-gamma SWPC: 11161
S878	2011.02.13		6	N21W32	0000		AXX
S880	2011.02.14			N07W67						plage
11162	2011.02.18 2011.02.17	20	28	N18W19	0150	DAI	DSI
S883	2011.02.18			S20W37						plage
Total spot count:		49	101
Sunspot number:		79	151

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.