Solar Terrestrial Activity Report

Last major update issued on June 13, 2011 at 03:55 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update June 1, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update June 1, 2011)]

[POES auroral activity level charts since October 2009 - updated June 11, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2109 [April-May 2011] - 2110 [May-June 2011] NEW
[Solar polar fields vs solar cycles - updated June 11, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on June 12. Solar wind speed ranged between 440 and 487 km/s under the influence of a high speed stream from CH454.

Solar flux measured at 20h UTC on 2.8 GHz was 84.6 (decreasing 7.6 over the last solar rotation). The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.0). Three hour interval K indices: 11123332 (planetary), 12234321 (Boulder).

The background x-ray flux is at the class B1 level.

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

Region 11234 decayed slowly and quietly.
Region 11235 was quiet and stable.

Spotted regions not numbered by NOAA/SWPC:
[S1060] emerged in the northeast quadrant on June 11. Location at midnight: N18E09
[S1061] emerged in the southeast quadrant on June 12. Location at midnight: S02E15

Coronal mass ejections (CMEs)

June 10-12: No obviously earth directed CMEs were observed.

Coronal holes

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

An elongated coronal hole (CH455) in the southern hemisphere was Earth facing on June 10-11.

The above coronal hole map is based on a new method where coronal holes are detected automatically. The method may need some fine tuning, however, 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 the new method, the extent and intensity of both holes 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. Propagation on long distance northeast-southwest paths is fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 13-15 with a chance of a few active intervals on June 13-14 due to effects from CH455.

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 SDO			SWPC	STAR	Current	Previous
11232	2011.05.31 2011.06.01			N08W73						plage
S1047	2011.06.04			S26W52						plage
S1048	2011.06.06			N22W49						plage
S1049	2011.06.06			S17W58						plage
S1052	2011.06.07			N11W07						plage
11234	2011.06.08 2011.06.09	6	11	S15E18	0010	BXO	BXO			location: S17E18
S1055	2011.06.09			S35W44						plage
11235	2011.06.10 2011.06.11		5	N14E13	0010		BXO
S1057	2011.06.10			S23E07						plage
S1058	2011.06.10			N16W57						plage
S1059	2011.06.11			N37W27						plage
S1060	2011.06.11		1	N18E09	0000		AXX
S1061	2011.06.12		2	S02E15	0000		AXX
Total spot count:		6	19
Sunspot number:		16	59

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.