Solar Terrestrial Activity Report

Last major update issued on July 5, 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 July 2, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update July 2, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update July 2, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 2, 2011)]

[POES auroral activity level charts since October 2009 - updated July 4, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2109 [April-May 2011] - 2110 [May-June 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to active on July 4. Solar wind speed ranged between 346 and 452 km/s. A high speed stream from CH462 was observed beginning at ACE near 15h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 85.0 (decreasing 11.4 over the last solar rotation). The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.4). Three hour interval K indices: 12212344 (planetary), 22212223 (Boulder).

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

At midnight UTC the visible solar disk had 5 spotted regions.

Region 11242 decayed again and had only a single small spot by the end of the day. The region is rotating over the northwest limb.
Region 11243 decayed slowly and quietly.
Region 11244 decayed losing spots, magnetic complexity and penumbral area.

Spotted regions not numbered by NOAA/SWPC:
[S1095] emerged in the northeastern quadrant on July 2. Location at midnight: N15E04
[S1096] rotated into view at the northeast limb on July 4. Location at midnight: S19E67

Coronal mass ejections (CMEs)

July 2 and 4: No obviously earth directed CMEs were observed.
July 3: A small CME was observed in STEREO and LASCO imagery after a B9 event in region 11244 early in the day.

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 trans equatorial coronal hole (CH462) was Earth facing on July 1-2. A coronal hole (CH463) in the northern hemisphere will rotate into an Earth facing position on July 5-6.

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 to good.

Forecast

The geomagnetic field is expected to be quiet to active on July 5 due to effects from CH462 becoming quiet on July 6-7. A high speed stream from CH463 could reach Earth late on July 8 and cause some unsettled and active intervals until July 10.

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
11242	2011.06.26 2011.06.28	2	1	N18W82	0005	BXO	AXX			location: N17W83
11243	2011.06.27 2011.06.28	5	11	N17W19	0040	CSO	CSO			location: N16W21 area: 0080
11244	2011.06.27 2011.07.01	7	8	N16W53	0120	DAO	CAO			area: 0050
S1088	2011.06.27			S25W58						plage
S1090	2011.06.29			N15E10						plage
S1091	2011.06.29			S23W48						plage
S1092	2011.06.30			S20W29						plage
S1093	2011.07.01			S05W37						plage
S1095	2011.07.02		3	N15E04	0000		BXO
S1096	2011.07.03		1	S19E67	0000		AXX
Total spot count:		14	24
Sunspot number:		44	74

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.