Solar Terrestrial Activity Report

Last major update issued on July 16, 2012 at 06:15 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 minor to very severe storm on July 15. Solar wind speed at SOHO ranged between 445 and 662 km/s under the influence of strong CME effects. After 06h Earth was embedded in a magnetic cloud with a very strong and persistent southwards Bz.

Solar flux measured at 20h UTC on 2.8 GHz was 140.5 (increasing 22.5 over the last solar rotation). The Potsdam WDC planetary A index was 92 (STAR Ap - based on the mean of three hour interval ap indices: 92.0). Three hour interval K indices: 56765686 (planetary), 45675543 (Boulder).

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

At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).

Region 11519 [S16W70] developed further and was the most active region on the visible disk producing several C flares.
Region 11520 [S17W46] decayed further and lost the magnetic delta structure and polarity intermixing. Only a single C flare was recorded.
Region 11521 [S21W63] decayed losing spots and penumbral area, only a single C flare was recorded.
Region 11522 [N12W63] developed slowly and quietly.
Region 11523 [S28W12] developed slowly and quietly.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1776 [S16W54] decayed slowly and quietly.
S1777 [S12W49] decayed slowly and quietly.
S1790 [N12W01] reemerged with a siingle tiny spot.
New region S1798 [S15E77] rotated into view with a single spot.
New region S1799 [S15W21] emerged with a few tiny spots.

Coronal mass ejections (CMEs)

July 13-15: 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 coronal hole (CH523) in the northern hemisphere rotated across the central meridian on July 14, the coronal hole may be too far to the north to cause geomagnetic effects. A coronal hole (CH524) in the southern hemisphere will likely rotate into an Earth facing position on July 18. 

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

Forecast

The geomagnetic field is expected to be unsettled to severe storm on July 16 and quiet to unsettled on July 17-18. There's a chance of weak effects from CH523 on July 17-18.

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
11518	2012.07.03 2012.07.04				N09W81
11519	2012.07.04	12	10	4	S17W68	0090	DAO	CSO
11520	2012.07.05 2012.07.06	35	33	20	S17W48	0960	FKC	DKC			location: S17W46 area: 0800 SWPC count, location, classification and area probably includes ARs S1776 and S1777
S1776	2012.07.05		11	6	S16W54	0020		CRI
S1777	2012.07.05		2	1	S12W49	0010		HRX
11521	2012.07.07 2012.07.09	17	13	10	S21W60	0300	EKI	ESO
11522	2012.07.07 2012.07.12	9	10	6	N13W62	0040	DAO	DAO			area: 0090
S1790	2012.07.10		1		N12W01	0000		AXX
S1791	2012.07.10				N12W24						plage
S1792	2012.07.10				N26W55						plage
11523	2012.07.11 2012.07.12	11	12	6	S28W08	0050	DAO	DSI
S1795	2012.07.13				N21E18						plage
S1796	2012.07.13				S28W42						plage
S1797	2012.07.14				N09E33						plage
S1798	2012.07.15		1	1	S15E77	0050		HSX
S1799	2012.07.15		3	2	S15W21	0000		BXO
Total spot count:		84	96	55
Sunspot number:		134	196	145	(total spot count + 10 * number of spotted regions)
Weighted penumbral SN:		119	137	96	(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):		80	69	80	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.