Solar Terrestrial Activity Report

Last major update issued on July 3, 2012 at 03:50 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 unsettled to minor storm on July 2. Solar wind speed at SOHO ranged between 566 and 735 km/s under the influence of a high speed stream from CH521.

Solar flux measured at 17h UTC on 2.8 GHz was 140.2 (increasing 1.5 over the last solar rotation, the measurement at 20h UTC was flare enhanced). The Potsdam WDC planetary A index was 30 (STAR Ap - based on the mean of three hour interval ap indices: 30.3). Three hour interval K indices: 45544443 (planetary), 45433333 (Boulder).

The background x-ray flux is at the class C1 level.

At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).

Region 11512 [S15W57] decayed slowly and quietly.
Region 11513 [N15W09] lost some of the polarity intermixing but remains capable of C and minor M class flaring. Flares: M1.1/1N at 00:35, C4.5/1F at 18:12, C6.5/1F at 23:39 UTC as well as several smaller C class events.
Region 11514 [S15W09] was quiet and stable.
Region 11515 [S17E04] developed further adding spots and penumbral area. The leading penumbra split into several penumbrae. There are two magnetic delta structures in penumbra in the southwestern part of the region. Further M class flaring is likely and there's a chance of an X class flare. Flares: C3.5 at 05:08 (associated with a weak type II radio sweep), major M5.6/2B at 10:52 (again associated with a weak type II radio sweep), M3.8/2B at 20:07, M2.0 at 23:56 UTC + several small C class events.
Region 11516 [N13E03] decayed slowly and quietly.
Region 11517 [N18E14] matured and was quiet.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1769 [N18E32] lost a few tiny spots.

Despite lots of flare activity on the visible disk, the most interesting events of the day occurred in clusters of sunspot regions located 1-3 days behind the east limb in both the southern an northern hemispheres. One of those events were associated with a full halo CME.

Coronal mass ejections (CMEs)

June 30 - July 2: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

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 large recurrent trans equatorial coronal hole (CH521) was in an Earth facing position on June 28 - July 1. 

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 good.

Forecast

The geomagnetic field is expected to be quiet to active on July 3 and quiet to unsettled on July 4-5 under the influence of a high speed stream from CH521.

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	2	2	1	S16W55	0120	CSO	CSO			location: N15W57
S1753	2012.06.25				S27W24						plage
11513	2012.06.25 2012.06.26	21	23	11	N16W09	0240	DAO	DSI			beta-gamma
11514	2012.06.26 2012.06.27	3	9	2	S14W13	0010	AXX	BXO			location: S15W09
11515	2012.06.26 2012.06.27	58	62	35	S17E04	0620	EAC	FKC			beta-gamma-delta area: 1150
S1758	2012.06.26				N14W54						plage
11516	2012.06.27 2012.06.29	5	8	3	N14E03	0010	CRO	CRO
S1762	2012.06.27				N03W27						plage
S1765	2012.06.29				S28W15						plage
11517	2012.06.30 2012.07.01	16	29	14	N19E14	0130	DAO	DAO			area: 0200
S1767	2012.06.30				N18W03
S1768	2012.06.30				N15W44						plage
S1769	2012.07.01		3	1	N18E32	0000		AXX
S1770	2012.07.01				N03E05						plage
S1771	2012.07.01				S15W43						plage
Total spot count:		105	136	67
Sunspot number:		165	206	137	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		128	164	95	(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):		99	72	75	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.