Solar Terrestrial Activity Report

Last major update issued on July 6, 2012 at 07:30 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 active on July 5. Solar wind speed at SOHO ranged between 445 and 653 km/s. Solar wind density increased slowly early in the day (the high speed stream from CH521 ended late on July 4), then dropped to very low levels at 06:00 UTC coinciding with a significant increase in solar wind speed (a possible reverse shock). After 10h and until 16:30 UTC density again generally increased slowly, then dropped significantly before suddenly increasing near 19h UTC and reached its highest level of the day just before 20h UTC. These sudden changes in density were reflected in GOES magnetometer measurements and an unsettled to active geomagnetic field. The source of these disturbances were likely recent activity in AR 11515 as there were no indications of a high speed coronal hole stream.

Solar flux measured at 17h UTC on 2.8 GHz was 150.8 (increasing 26.6 over the last solar rotation, the measurement at 20h UTC was flare enhanced. Adjusted to 1 AU and removing all flare enhanced measurements, this is the highest solar flux in 2012). The Potsdam WDC planetary A index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 14.3). Three hour interval K indices: 22144323 (planetary), 22134333 (Boulder).

The background x-ray flux is at the class C2 level.

At midnight UTC the visible solar disk had 14 spotted active regions (in 2K resolution SDO images).

Region 11513 [N15W51] decayed losing most of the small spots and simpified magnetically. The single penumbra was mostly unchanged.
Region 11514 [S18W49] decayed further and could soon become spotless.
Region 11515 [S17W38] lost a few spots and what was a major magnetic delta decreased in size and importance. There are currently small magnetic delta structures in all large penumbrae. M class flares are highly likely and there's a chance of an X class flare. Flares: M1.2 at 00:38, M3.7 at 01:10, M1.2 at 01:31, C9.9 at 01:41, C8.1 at 02:05, C7.9 at 02:26, M3.3 at 02:42, M1.1 at 03:31, M7.8 at 03:36, M3.0 at 03:42, M1.1 at 04:45, C8.5 at 05:05, M1.2 at 06:53, M1.6 at 07:45, C8.0 at 09:30, M2.3 at 10:48, C9.2 at 10:56, M8.7 at 11:44, M1.4 at 13:20, C9.5 at 13:55, C8.4 at 14:46, C6.1 at 15:59 ... UTC. In addition 2 M and several C flares were recorded later in the day. The flare list is according to SDO/SAM/EVE 1 minute measurements.
Region 11517 [N19W26] added a few spots but lost mature penumbra.
Region 11518 [N09E53] was quiet and stable.
Region 11519 [S16E62] was quiet and stable.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1767 [N20W38] developed slowly and quietly.
S1769 [N16W13] quietly added a few spots.
S1774 [S26E64] lost a spot and was quiet.
New region S1775 [S19E84] rotated partly into view revealing large spots and a compact structure. M class flaring is possible.
New region S1776 [S16E75] rotated into view with a single small spot.
New region S1777 [S13E87] rotated partly into view with a single spot.
New region S1778 [S28W13] emerged with a single small spot.
New region S1779 [N15E03] emerged with a tiny spot.

Coronal mass ejections (CMEs)

July 3 and 5: 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 6-7. 

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.

Forecast

The geomagnetic field is expected to be quiet to active on July 6-8 with a chance of occasional minor storm intervals due to the recent CMEs from ARs 11515 and 11513.

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
11513	2012.06.25 2012.06.26	5	3	2	N15W52	0240	CSO	CHO			area: 0280
11514	2012.06.26 2012.06.27		1		S14W54	0000		AXX			location: S18W49
11515	2012.06.26 2012.06.27	56	91	44	S17W36	0670	EKC	FKC			beta-gamma-delta area: 1300 location: S17W38
11516	2012.06.27 2012.06.29				N14W39						plage
S1765	2012.06.29				S28W54						plage
11517	2012.06.30 2012.07.01	5	17	7	N18W27	0010	BXO	DRO			area: 0040
S1767	2012.06.30		9	2	N20W38	0010		BXO
S1769	2012.07.01		10	3	N16W13	0000		AXX
S1770	2012.07.01				N03W35						plage
11518	2012.07.03 2012.07.04	5	7	3	N09E52	0010	BXO	CAO			area: 0040
S1773	2012.07.03				N23W51						plage
11519	2012.07.04	1	1	1	S15E63	0120	HSX	HSX
S1774	2012.07.04		1		S26E64	0000		AXX
S1775	2012.07.05		4	2	S19E84	0500		DKC
S1776	2012.07.05		1		S16E75	0000		AXX
S1777	2012.07.05		1	1	S13E87	0090		HSX
S1778	2012.07.05		1	1	S28W13	0000		AXX
S1779	2012.07.05		1		N15E03	0000		AXX
Total spot count:		72	148	66
Sunspot number:		122	288	166	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		92	196	114	(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):		73	101	91	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.