Solar Terrestrial Activity Report

Last major update issued on July 5, 2012 at 05:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-24 (last update June 2, 2012)] [Cycle 24 progress NEW]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 1, 2012)]

[POES auroral activity level since October 2009 - updated July 2, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on July 4. Solar wind speed at SOHO ranged between 449 and 585 km/s under the decreasing influence of a high speed stream from CH521.

Solar flux measured at 17h UTC on 2.8 GHz was 149.2 (increasing 21.0 over the last solar rotation, the measurement at 20h UTC was flare enhanced). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.6). Three hour interval K indices: 33332113 (planetary), 33332312 (Boulder).

The background x-ray flux is at the class C5 level.

At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).

Region 11512 [S15W84] added trailing spots and was quiet.
Region 11513 [N15W37] decayed slowly and remains capable of producing C and M class flares. Flare: M1.8/2N at 16:39 UTC. This event was associated with a very weak type II radio sweep and a small CME. The CME was observed off the east limb in STEREO-A and west limb in STEREO-B and could reach Earth on July 7. The CME was not easily observed in LASCO imagery.
Region 11514 [S16W36] decayed slowly and quietly.
Region 11515 [S18W25] displayed impressive development in the central spot section. Several magnetic delta structures are evident as negative polarity spots are trapped inside positive polarity flux. This has caused a significant increase in the background x-ray level. There's a high probability of major M or X class flares. Flares: C5.1/1F at 01:45, C6.1 at 04:10, M2.3 at 04:37, C6.7 at 09:06, major M5.3/2B at 09:55, C5.8 at 11:17, C5.6 at 14:13, M1.3/1F at 14:40, C8.2 at 14:49, C6.4 at 15:50, C6.9 at 16:12, C9.5 at 21:27, M4.6 at 22:09, C7.4 at 22:45, M1.2 at 23:55 UTC.
Region 11516 [N12W53] decayed slowly and quetly.
Region 11517 [N19W13] decayed slowly and quietly.
New region 11518 [N09E68] rotated into view on July 3 and was numbered by SWPC the next day.
New region 11519 [S15E76] rotated into view with a single spot.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1767 [N20W24] was quiet and stable.
S1769 [N16E03] was quiet and stable.
New region S1774 [S25E73] rotated into view with two small spots.

Coronal mass ejections (CMEs)

July 2-3: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
July 4: A weak CME observed after an M1 flare in AR 11513 could reach Earth on July 7.

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 coronal hole (CH522] in the northern hemisphere could rotate into an Earth facing position on July 6. 

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

Forecast

The geomagnetic field is expected to be quiet to unsettled on July 5-7 with a chance of active intervals on July 7 if the CME observed on July 4 reaches Earth.

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
			2K	1K
11512	2012.06.24 2012.06.25	1	3	1	S15W84	0080	HSX	CSO
S1753	2012.06.25				S27W50						plage
11513	2012.06.25 2012.06.26	13	15	9	N17W36	0160	CSO	DHO			beta-gamma area: 0290 location: N15W37
11514	2012.06.26 2012.06.27		3	1	S14W41	0000		AXX			location: S16W36
11515	2012.06.26 2012.06.27	45	105	59	S17W23	0640	FKC	FKC			beta-gamma-delta area: 1400 location: S18W25
11516	2012.06.27 2012.06.29		4	1	N14W25	0000		BXO
S1762	2012.06.27				N03W53						plage
S1765	2012.06.29				S28W41						plage
11517	2012.06.30 2012.07.01	7	14	6	N19W13	0070	DSO	CAO			area: 0170
S1767	2012.06.30		2		N20W24	0000		AXX
S1769	2012.07.01		7	3	N16E03	0000		AXX
S1770	2012.07.01				N03W22						plage
11518	2012.07.03 2012.07.04	2	6	3	N09E65	0010	AXX	CAO			area: 0030 location: N09E68
S1773	2012.07.03				N23W38						plage
11519	2012.07.04	1	1	1	S14E76	0030	HSX	HSX			area: 0080
S1774	2012.07.04		2		S25E73	0000		BXO
Total spot count:		69	162	84
Sunspot number:		129	272	174	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		99	177	124	(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):		77	95	96	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) for STAR SDO 2K, k = 0.55 for STAR SDO 1K

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 quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.