Solar Terrestrial Activity Report

Last major update issued on January 29, 2012 at 07:00 UTC.

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

[POES auroral activity level since October 2009 - updated January 27, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2117 [November-December 2011] - 2118 [December 2011 - January 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet on January 28. Solar wind speed ranged between 377 and 481 km/s, weakly under the influence of a high speed stream from CH496.

Solar flux measured at 20h UTC on 2.8 GHz was 114.5 (decreasing 15.5 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0). Three hour interval K indices: 11100022 (planetary), 21112212 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight UTC the visible solar disk had 6 spotted regions (in 2K resolution SDO images).

Region 11408 [N08W23] was quiet and stable.
Region 11410 [N19E49] added trailing spots and was quiet.
New region 11411 [S25E08] emerged in the southeast quadrant on January 26 and was noticed by SWPC two days later. The region decayed slowly on January 28.

Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1446] rotated into view at the southeast limb on January 24. Location at midnight: S21E24
[S1451] emerged in the northeast quadrant on January 27. Location at midnight: N08E46
[S1452] emerged in the southwest quadrant on January 28. Location at midnight: S14W27

Coronal mass ejections (CMEs)

January 26, 28: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
January 27: The X1 limb event in region 11402 was associated with a very fast and wide asymmetric full halo CME (in LASCO imagery). Due to the location of the event it is unclear if the extension to a full halo event is caused by backsided or frontsided material. If frontsided there's a chance of a flank CME impact on January 29 or 30.

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 trans equatorial coronal hole (CH498) will likely rotate into an Earth facing position on January 31.

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

Forecast

The geomagnetic field is expected to be initially quiet on January 29. If the CME observed on January 27 reaches Earth, some active and minor storm intervals will be possible late in the day and on January 30. Quiet conditions are likely on January 31.

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
11405	2012.01.15 2012.01.16			N13W88						plage
11409	2012.01.20 2012.01.21			N18W42						plage
11408	2012.01.20 2012.01.21	2	5	N08W25	0060	HAX	CAO			area: 0130 location: N08W23
S1441	2012.01.22			S13W08						plage
S1442	2012.01.22			N12W59						plage
S1446	2012.01.24		10	S21E24	0000		BXO
S1448	2012.01.25			S17W32
11410	2012.01.26	1	7	N16E38	0150	HSX	CHO			area: 0290 location: N19E49
11411	2012.01.26 2012.01.28	1	5	S26E09	0000	AXX	AXX
S1450	2012.01.26			S20W22						plage
S1451	2012.01.27		4	N08E46	0000		BXO
S1452	2012.01.28		2	S14W27	0010		CRO
Total spot count:		4	33
Sunspot number:		34	93	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		14	51	(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):		20	42	k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1, 2011) for STAR SDO

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.