Solar Terrestrial Activity Report

Last major update issued on May 29, 2014 at 03:45 UTC.

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

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated April 17, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was very quiet on May 28. Solar wind speed at SOHO ranged between 302 and 348 km/s.

Solar flux at 20h UTC on 2.8 GHz was 99.4 (decreasing 26.3 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 143.6. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.5). Three hour interval K indices: 11011111 (planetary), 22011312 (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 in 2K resolution (SN: 100) and 6 active regions in 1K resolution (SN: 75) SDO images on the visible solar disk.

Region 12071 [S09W48] decayed slowly and quietly.
Region 12073 [S13W25] decayed slowly and quietly.
Region 12075 [S09E12] decayed slowly and quietly.
New region 12076 [S19W14] emerged on May 27 and was numbered the next day by SWPC.

Spotted regions not numbered (or interpreted differently) by SWPC:
New region S3477 [N14E27] emerged with a penumbra spot.
New region S3478 [N19W58] emerged with a penumbra spot.
New region S3479 [N01W50] emerged with penumbra spots.

C2+ Flares (SDO/EVE):

Coronal mass ejections (CMEs)

May 26-28: 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 (CH619) in the northern hemisphere was in an Earth facing position on May 25-26.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet on May 29-31.

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
12069	2014.05.17 2014.05.18	1			S17W83	0010	AXX				see AR S3470 location: S19W80
12071	2014.05.19	1	5	2	S09W47	0010	AXX	CRO
12073	2014.05.20 2014.05.21	11	14	6	S13W29	0020	CRI	DRI			location: S13W25
12075	2014.05.23	2	1	1	S09E10	0060	HSX	HSX			location: S09E12 area: 0080
S3466	2014.05.24				N12W54						plage
S3467	2014.05.24				S20W05						plage
S3470	2014.05.26				S17W82						plage
S3471	2014.05.26				N16W29						plage
S3472	2014.05.27				S17W29						plage
12076	2014.05.27 2014.05.28	7	6	4	S19W14	0050	DAO	DRO
S3474	2014.05.27				N08E13						plage
S3475	2014.05.27				S09W58						plage
S3477	2014.05.28		1	1	N14E27	0005		BXO
S3478	2014.05.28		1		N19W58	0001		AXX
S3479	2014.05.28		2	1	N01W58	0003		AXX
Total spot count:		22	30	15
Sunspot number:		72	100	75	(total spot count + 10 * number of spotted regions)
Weighted SN:		35	44	29	(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):		43	35	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.