Solar Terrestrial Activity Report

Last major update issued on October 6, 2013 at 05:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update October 1, 2013)] [Cycle 24 progress (last update October 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update October 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update October 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update September 5, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated September 24, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was inactive on October 5. Solar wind speed at SOHO ranged between 320 and 387 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 105.9 (increasing 10.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 112.3. The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.0). Three hour interval K indices: 00000000 (planetary), 00001210 (Boulder).

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

At the time of counting spots (see image time) spots were observed in 5 active regions in 2K resolution (SN: 89) and 5 active regions in 1K resolution (SN: 63) SDO images on the visible solar disk.

Region 11855 [S12W55] decayed quickly and quietly.
Region 11856 [N08E30] was quiet and stable.
Region 11857 [S07E29] was quiet and stable.
Region 11859 [S15W22] decayed slowly and quietly.

Spotted regions not numbered by SWPC:
S2733 [S24E08] developed slowly and quietly.

Coronal mass ejections (CMEs)

October 3-5: 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 coronal hole (CH589) in the northern hemisphere will rotate into an Earth facing position on October 5-7.

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

Forecast

The geomagnetic field is expected to be quiet on October 6-7. Effects from CH589 could cause a few unsettled intervals on October 8-9 and unsettled to active conditions on October 10.

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 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	STAR SDO				SWPC	STAR	Current	Previous
			2K	1K
S2718	2013.09.26				S20W55						plage
11854	2013.09.27 2013.09.28				N05W39						plage location: N07W31
11855	2013.09.28 2013.09.30	9	8	5	S13W53	0070	DAO	CRO			location: S12W55
11857	2013.10.01 2013.10.02	1	5	1	S08E28	0110	HSX	CSO			area: 0200 location: S07E29
11856	2013.10.01 2013.10.02	5	18	4	N08E31	0070	CAO	CSO
11858	2013.10.02 2013.10.03	2			N12W95	0060	DAO				rotated out of view
S2729	2013.10.02				S12W03						plage
S2730	2013.10.02				N11W21						plage
11859	2013.10.02 2013.10.04	2	3	1	S15W23	0010	AXX	AXX
S2732	2013.10.03				S25E37						plage
S2733	2013.10.03		5	2	S24E08	0018		CRO
S2734	2013.10.04				N24E06						plage
Total spot count:		19	39	13
Sunspot number:		69	89	63	(total spot count + 10 * number of spotted regions)
Weighted SN:		39	55	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):		41	31	35	k * (sunspot number). k = 0.6 for SWPC, k = 0.35 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) 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 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.