Solar Terrestrial Activity Report

Last major update issued on March 1, 2015 at 04:35 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, 2015)] [Cycle 24 progress (last update February 1, 2015) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2015)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 1, 2015)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 1, 2015)]

[Noon SDO sunspot count 1K Reference: 4K (large file) (updated daily)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated February 21, 2015]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet to unsettled on February 28. Solar wind speed at SOHO ranged between 308 and 461 km/s, gradually increasing as a co-rotating interaction region associated with an extension of the southern polar coronal hole became geoeffective.

Solar flux at 20h UTC on 2.8 GHz was 123.4 (decreasing 18.3 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 139.5. The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.9). Three hour interval K indices: 12222333 (planetary), 01323433 (Boulder).

The background x-ray flux is at the class B7 level.

At the time of counting spots (see image time), spots were observed in 6 active regions using 2K resolution (SN: 154) and 4 active regions using 1K resolution (SN: 92) SDO images on the visible solar disk.

Region 12290 [N20W67] lost the trailing spots. New positive polarity flux emerged just north of the leading polarity spots causing the region to become unstable. A magnetic delta structure could easily form if development continues due to the close proximity of the opposite polarity fields.
Region 12292 [S09W15] developed as new flux emerged.
Region 12293 [N06E17] gained spots, however, the magnetic delta disappeared.
Region 12294 [S14W28] decayed quickly after producing a few C flares.

Spotted regions not numbered (or interpreted differently) by SWPC:
New region S4248 [S37E31] emerged at a high latitude with a penumbra spot.
New region S4249 [S16W08] emerged with a penumbra spot.

C2+ flares (GOES):

Coronal mass ejections (CMEs)

February 26-27: No obviously Earth directed CMEs were observed in LASCO imagery.
February 28: No LASCO imagery. Two interesting events which may have produced CMEs with Earth directed components were observed. The first was the C5 flare in AR 12294, the second a filament eruption in the northwest quadrant close to the central meridian. The latter event began at approximately 13:55 UTC.

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]

An extension of the southern polar coronal hole rotated across the central meridian on February 26-27 and could be associated with a co-rotating interaction region. A recurrent trans equatorial coronal hole (CH657) will likely rotate into an Earth facing position on March 3-4.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on March 1-2 due to effects from a co-rotating interaction region and quiet to unsettled on March 3-4.

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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% 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	Magnetic (SDO)				SWPC	STAR	Current	Previous
			2K	1K
12289	2015.02.17 2015.02.18				S10W65
12290	2015.02.18	3	6	4	N22W63	0040	CAO	DAO			area: 0090 location: N20W67
S4239	2015.02.21				S21W43
12291	2015.02.21 2015.02.22				N13W86
12292	2015.02.22 2015.02.23	1	16	6	S09W16	0010	AXX	CAO			area: 0050
12293	2015.02.23 2015.02.26	16	52	30	N06E15	0080	DAC	DAC	images/AR_12293_20150228_2345.png		area: 0180
S4244	2015.02.26				S22E26
12294	2015.02.26 2015.02.27	10	18	12	S14W28	0090	DAI	DRI
S4246	2015.02.27				N17E21
S4248	2015.02.28		1		S37E31	0003		AXX
S4249	2015.02.28		1		S16W08	0003		AXX
Total spot count:		30	94	52
Sunspot number:		70	154	92	(total spot count + 10 * number of spotted regions)
Weighted SN:		42	112	70	(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):		35	54	51	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

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 WDC-SILSO 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 GFZ Potsdam WDC ap indices.

This report has been prepared by Jan Alvestad. It is based on the 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.