Solar Terrestrial Activity Report

Last major update issued on January 6, 2011 at 04:20 UTC. Minor update posted at 20:45 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, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update January 2, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update January 2, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports from January 2003 (last update January 1, 2011)]

[POES auroral activity level charts since October 2009]
[Annotated geomagnetic activity chart - Carrington rotation 2104 - NEW]

The geomagnetic field was very quiet on January 5. Solar wind speed ranged between 344 and 438 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 87.7 (up 0.9 over the last solar rotation). The planetary A index  was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.5). Three hour interval K indices: 00011000 (planetary), 00021211 (Boulder).

The background x-ray flux is at the class A8 level.

At midnight UTC the visible solar disk had 4 spotted regions.

Region 11140 displayed no significant changes and was quiet.
Region 11142 decayed slowly and still has quite a few small spots.

Spotted regions not numbered by NOAA/SWPC:
[S858] This region emerged in the northwest quadrant on January 5. Location at midnight: N19W33
[S859] A new region emerged in the southeast quadrant on January 5. Location at midnight: S23E46

Minor update added at 20:45 UTC: A high speed stream from CH431 is in progress. Solar wind density reached very high levels at ACE and peaked around 20h UTC. The interplanetary magnetic field has swung strongly southwards. Minor and even major geomagnetic storming is possible for the remainder of the day and early on January 7. The disturbance appears to be much stronger than anticipated.

January 3-5: No obviously Earth directed CMEs were observed in LASCO or STEREO images.

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

A coronal hole (CH431) in the northern hemisphere was in an Earth facing position on January 3-4. A recurrent trans equatorial coronal hole (CH432) was Earth facing on January 4-5. A recurrent coronal hole (CH433) in the northern hemisphere will likely rotate into an Earth facing position on January 9-11.

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

The geomagnetic field is expected to be quiet on January 6. Although mostly quiet conditions are likely on January 7, weak effects from CH431 are possible. CH432 could cause quiet to active conditions on January 8-9. Mostly quiet conditions are likely on January 10-11.

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 (Recent map)

Compare to the previous day's image

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	Spot count		Location at midnight	Area	Classification		SDO (NASA) / AIA 4500 image		Comment
		SWPC	STAR			SWPC	STAR	Current	Previous
11139	2010.12.27			S30W49						plage
11141	2011.01.01	3		N34W76	0020	BXO				spotless
11140	2010.12.31	3	4	N34E01	0190	CSO	CSO
11142	2011.01.01	14	13	S13W18	0040	CAO	BXI
S858	2011.01.05		2	N19W33	0000		BXO
S859	2011.01.05		2	S23E46	0010		BXO
Total spot count:		20	21
Sunspot number:		50	61

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 international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the 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.