Solar Terrestrial Activity Report

Last major update issued on July 21, 2014 at 07:50 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update July 1, 2014)] [Cycle 24 progress (last update July 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update July 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update July 1, 2014)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 5, 2014)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated July 18, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was very quiet on July 20. Solar wind speed at SOHO ranged between 275 and 321 km/s.

Solar flux at 20h UTC on 2.8 GHz was 87.1 (decreasing 5.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 134.3. The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.3). Three hour interval K indices: 10001101 (planetary), 00111211 (Boulder).

The background x-ray flux is at the class B2 level.

At the time of counting spots (see image time), spots were observed in 7 active regions using 2K resolution (SN: 94) and 6 active regions using 1K resolution (SN: 75) SDO images on the visible solar disk.

Region 12118 [N07W55] decayed slowly and quietly.
Region 12119 [S22W12] developed slowly and was quiet.
New region 12120 [N17W31] emerged on July 18 and was numbered by SWPC 2 days later as the region decayed.

Spotted regions not numbered (or interpreted differently) by SWPC:
New region S3654 [N09E49] was observed with penumbra spots.
New region S3655 [S19E07] was observed with a penumbra spot.
New region S3656 [S07W19] emerged with a penumbra spot.
New region S3657 [N11W51] emerged with a penumbra spot.

C2+ Flares (GOES):

Coronal mass ejections (CMEs)

July 18-20: 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 recurrent southern hemisphere coronal hole (CH627) could rotate into an Earth facing position on July 20-21.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is fair to good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on July 21-23. On July 24-25 there's a chance of a few unsettled intervals should a stream from CH627 reach 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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.

Active solar regions

(Click on image for 2K resolution) Compare to the previous day's image. 0.5K image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue 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	Magnetic (SDO)				SWPC	STAR	Current	Previous
			2K	1K
S3644	2014.07.15				S16W28						plage
12118	2014.07.17 2014.07.18	2	1	1	N07W56	0010	AXX	AXX			area: 0004
S3647	2014.07.17				N16W40						plage
S3648	2014.07.17				N11W48						plage
12119	2014.07.18	7	16	10	S22W13	0040	DAO	DAO			area: 0130
12120	2014.07.18 2014.07.20	2	2	1	N17W30	0010	AXX	AXX
S3653	2014.07.19				N25W44						plage
S3654	2014.07.20		2		N09E49	0005		AXX
S3655	2014.07.20		1	1	S19E07	0003		AXX
S3656	2014.07.20		1	1	S07W19	0003		AXX
S3657	2014.07.20		1	1	N11W51	0004		AXX
Total spot count:		11	24	15
Sunspot number:		41	94	75	(total spot count + 10 * number of spotted regions)
Weighted SN:		16	29	20	(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):		25	33	41	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

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 WDC-SILSO international sunspot number is typically 30-50% lower. 2B) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international GFZ Potsdam WDC ap indices.

This report has been prepared by Jan Alvestad. It is based on the 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.