Solar Terrestrial Activity Report

Last major update issued on January 22, 2012 at 06:35 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 20, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2117 [November-December 2011] - 2118 [December 2011 - January 2012] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet on January 21. Solar wind speed ranged between 287 and 319 km/s. A weak solar wind shock was observed near 04h UTC at ACE. Taking into account the low solar wind speed this event may be related to the CME observed on January 16. A strong solar wind shock was observed at ACE near 05:15 UTC on January 22, likely the arrival of the CME observed on January 19. Initially the interplanetary magnetic field has been very strongly northwards.

Solar flux measured at 20h UTC on 2.8 GHz was 141.6 (decreasing 2.7 over the last solar rotation). The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.1). Three hour interval K indices: 12122122 (planetary), 22132222 (Boulder).

The background x-ray flux is at the class B6 level.

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

Region 11401 [N17W13] lost penumbral area and gained spots in the trailing spot section while the leading penumbra split into two. If the current separation between the leading and trailing spot section increases the region could be split. M class flares are possible.
Region 11402 [N30W08] remains capable of producing further M class flares. The large penumbra has taken on a symmetrical shape.
Region 11405 [N13E03] decayed slowly and quietly.
Region 11407 [N18W26] matured and was quiet. The region is close to getting an EAI classification.
New region 11408 [N08E70] rotated into view at the northeast limb on January 20 and was numbered by SWPC one day later.
New region 11409 [N17E52] emerged in the northeast quadrant on January 20 and got an SWPC number the next day.

Coronal mass ejections (CMEs)

January 20-21: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
January 19: A full halo CME was observed after the M3.2 LDE in region 11402.

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 (CH495) in the southern hemisphere was in an Earth facing position on January 20. A large recurrent coronal hole (CH496) in the southern hemisphere could rotate into an Earth facing position on January 24-26. A new coronal hole (CH497) will likely become Earth facing on January 22.

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

Forecast

The geomagnetic field is expected to be quiet to major storm on January 22 due to CME effects. Should the IMF swing fully southwards at the current level of the total field, severe storming will be possible. If the IMF stays northwards there will only be a minor geomagnetic disturbance. Quiet to unsettled is likely on January 23-26.

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
11396	2012.01.09 2012.01.12			N25W86						plage
S1424	2012.01.11			S16W57						plage
11397	2012.01.12 2012.01.13			S20W82						plage
11399	2012.01.13 2012.01.14			S23W25						plage
11401	2012.01.14	19	47	N17W12	0350	EKI	FSI			beta-gamma
11402	2012.01.14	7	16	N29W11	0360	DKO	CHO			beta-gamma location: N30W08 area: 0500
11403	2012.01.14 2012.01.15			S19W52						plage
11405	2012.01.15 2012.01.16	4	8	N13E01	0030	CSO	CRO			location: N13E03
S1436	2012.01.16			N16W01						plage
S1437	2012.01.16			N17W57						plage
11407	2012.01.18	10	18	N17W28	0070	DRO	DAI			location: N18W26
11409	2012.01.20 2012.01.21	1	4	N16E50	0000	AXX	BXO			location: N17E52
11408	2012.01.20 2012.01.21	1	2	N06E68	0120	HAX	HAX
Total spot count:		42	95
Sunspot number:		102	155	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		75	123	(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):		61	70	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.