Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 29, 2013 at 04:20 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 October 9, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated October 10, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was very quiet on October 28. Solar wind speed at SOHO ranged between 270 and 320 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 159.9 (increasing 53.1 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 117.0. The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.4). Three hour interval K indices: 00100000 (planetary), 12101211 (Boulder).

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

At the time of counting spots (see image time) spots were observed in 8 active regions in 2K resolution (SN: 209) and 8 active regions in 1K resolution (SN: 145) SDO images on the visible solar disk.

Region 11875  [N06W81] was very active during the day. The region has a magnetic delta structure in the southern part of the large penumbra. A major proton flare is possible while the region transits the west limb. C5+ flares: major X1.0/2N at 02:03 (associated with a partial halo CME), major M5.1/2B at 04:41, C5.2 at 09:22, M2.8/1N at 14:05, long duration M1.9 event pekaing at 15:54 (unreported by SWPC), M1.5 at 20:57 UTC.
Region 11877 [S12W57] decayed slowly but could still produce occasional flares.
C5+ flares: M1.4/2N at 11:53 UTC
Region 11879 [S12W42] decayed slowly and quietly.
Region 11882 [S10E21] still has a magnetic delta structure and could produce a major flare.
C5+ flares: M2.7/1N at 15:01, M4.4 at 15:15 UTC. A full halo CME was associated with the M flares.
Region 11883 [N02E45] was quiet and stable (this is actually a southern hemisphere region).
Region 11884 [S15E54] developed slowly and could produce a major flare.

Spotted regions not numbered by SWPC:
New region S2784 [S17E08] decayed slowly and quietly.
New region S2787 [N13E06] emerged with a few spots.

Coronal mass ejections (CMEs)

October 26: An asymmetric halo CME was observed after the M1.8 LDE near 11h. Due to many other CMEs it is difficult to determine if this one was full or partial halo. The CME could reach Earth on October 29.
October 27: The CMEs originating in AR 11875 does not appear to be Earth directed.
October 28: A partial halo CME was observed in LASCO imagery after the X1 flare early in the day. The CME could reach Earth on October 30 or 31. A full halo CME was observed after an M4.4 event in AR 11882 and could reach Earth on October 30 or 31.

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 small coronal hole near the center of the disk will be in an Earth facing position on October 29.

Coronal hole map

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 due to enhanced proton levels. Propagation on long distance northeast-southwest paths is fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on October 29 becoming quiet to minor storm on October 30-31 due to CME effects.

Coronal holes (1) Coronal mass ejection (2) M and X class flares (3)
     

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
11875 2013.10.16
2013.10.17
15 13 7 N06W78 0770 EKC EKC beta-delta

area: 0950

11877 2013.10.18 13 13 6 S12W56 0230 DAI CHO  
11879 2013.10.21 6 15 4 S12W41 0070 DAO CAO

 

11881 2013.10.22
2013.10.24
3     S22W20 0010 BXO     spotless
S2776 2013.10.22       N08W44           plage
S2777 2013.10.22       N35W47           plage
11882 2013.10.23
2013.10.24
24 36 24 S08E21 0330 DKC DKC beta-gamma-delta

area: 0500

location: S10E21

S2780 2013.10.24       S10W06           plage
S2781 2013.10.25       N26E09           plage
11883 2013.10.26 3 4 3 N04E45 0040 CSO HRX location: N02E45
11884 2013.10.26 10 34 13 S14E53 0130 DAO EKC beta-gamma

area: 0520

location: S15E54

11885 2013.10.26 1     S17E49 0170 HSX       part of AR 11884
S2784 2013.10.27   8 5 S17E08 0027   CRO  
S2786 2013.10.27       N07W08         plage
S2787 2013.10.28   6 3 N13E06 0016   AXX    
Total spot count: 75 129 65  
Sunspot number: 155 209 145  (total spot count + 10 * number of spotted regions)
Weighted SN: 120 180 116  (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): 93 73 80 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

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2011.11 153.5 (cycle peak) 96.7 (cycle peak) 61.1 (+1.2) 5.55
2012.02 106.5 32.9 66.9 (+1.4)
likely cycle 24 max
8.81
2012.06 119.6 64.5 58.9 (-2.8) 10.08
2012.07 133.9 66.5 57.8 (-1.1) 13.90
2012.08 115.4 63.0 58.2 (+0.4) 7.96
2012.09 122.9 61.4 58.1 (-0.1) 8.07
2012.10 123.3 53.3 58.6 (+0.5) 9.97
2012.11 121.3 61.8 59.7 (+1.1) 7.08
2012.12 108.6 40.8 59.6 (-0.1) 3.44
2013.01 127.1 62.9 58.7 (-0.9) 4.69
2013.02 104.3 38.0 58.4 (-0.3) 6.11
2013.03 111.3 57.9 57.5 (-0.9) 10.56
2013.04 124.8 72.4 (56.2 projected, -1.3) 5.40
2013.05 131.4 78.7 (55.8 projected, -0.4) 9.73
2013.06 110.1 52.5 (56.0 projected, +0.2) 12.60
2013.07 115.5 57.0 (56.1 projected, +0.1) 9.47
2013.08 114.6 66.0 (55.9 projected, -0.2) 8.27
2013.09 102.6 36.9 (55.4 projected, -0.5) 5.23
2013.10  130.6 (1) 113.3 (2A) / 125.4 (2B) / 73.6 (2C) (53.9 projected, -1.5) (7.67)

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.