Solar Terrestrial Activity Report

Last major update issued on June 26, 2011 at 04:35 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 24, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2109 [April-May 2011] - 2110 [May-June 2011]
[Solar polar fields vs solar cycles - updated June 11, 2011]

Recent activity

The geomagnetic field was quiet on June 25. Solar wind speed ranged between 526 and 618 km/s under the influence of a high speed stream from CH457. A transition to a high speed stream from CH459 was observed at ACE near 23h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 93.6 (decreasing 17.2 over the last solar rotation). The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.0). Three hour interval K indices: 22211222 (planetary), 22221222 (Boulder).

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

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

Region 11236 decayed and lost all spots outside of the large penumbra. The region will rotate over the northwest limb today.
Region 11240 decayed and could soon become spotless.
Region 11241 was quiet and lost leading polarity spots.

Spotted regions not numbered by NOAA/SWPC:
[S1084] emerged in the northwest quadrant on June 25. Location at midnight: N16W08

Coronal mass ejections (CMEs)

June 23-25: 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

A coronal hole (CH459) in the northern hemisphere was Earth facing on June 23. A recurrent coronal hole (CH460) in the northern hemisphere will likely rotate into an Earth facing position on June 27-28.

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 26 with a chance of active intervals due to effects from CH459. Quiet to unsettled is likely on June 27 becoming quiet on June 28-29.

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
11236	2011.06.13 2011.06.14	1	1	N15W74	0090	HSX	HHX			area: 0250 location: N16W78
11237	2011.06.16 2011.06.17			S18W43						plage
11239	2011.06.17 2011.06.20	1		N15W56	0000	AXX				plage
S1073	2011.06.19			S05W35						plage
11240	2011.06.20	2	6	S20W26	0005	AXX	BXO			location: S21W25
S1076	2011.06.21			S09W16						plage
11241	2011.06.22 2011.06.24	3	15	N18W19	0010	BXO	CRO
S1079	2011.06.23			N08E24						plage
S1080	2011.06.23			S24W47						plage
S1082	2011.06.23			N23W34						plage
S1083	2011.06.24			N25E13						plage
S1084	2011.06.25		1	N16W08	0000		AXX
Total spot count:		7	23
Sunspot number:		47	63

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.