Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 19, 2015 at 05:40 UT. Updates may be incomplete until October 25.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data from 2003.01 (October 1, 2015)
Solar cycle Solar cycles 23-24 (October 1, 2015) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (October 1, 2015) Noon SDO sunspot count 1K Reference: 4K (large file) (*)
  Solar cycles 1-24 (July 17, 2015) POES auroral activity level October 2009 - December 2012
  Comparison of cycles 21, 22, 23 and 24 (October 1, 2015) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (October 1, 2015) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs solar cycles (October 13, 2015)  

Recent activity

The geomagnetic field was quiet to minor storm on October 18. Solar wind speed at SOHO ranged between 335 and 358 km/s. A disturbance that began early in the day was likely associated with the southeasternmost part of CH695, a section which was Earth facing on October 14.

Solar flux at 20h UTC on 2.8 GHz was 119.5 (increasing 16.1 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 102.6. The Potsdam WDC planetary A index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 16.6). Three hour interval K indices: 33353322 (planetary), 33454322 (Boulder).

The background x-ray flux is at the class B4 level.

At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 196) and 9 active regions using 1K resolution (SN: 136) SDO images on the visible solar disk.

Region 12431 [S18W28] decayed slowly and quietly.
Region 12434 [S10E07] was mostly quiet. There is a weak magnetic delta in a penumbra just north of the largest penumbra.
Region 12435 [S14E46] was quiet and stable.
Region 12436 [N09E59] developed with new flux emerging in the central and trailing spot sections. An M class flare is possible.
New region 12437 [S20E72] rotated quietly into view. This region was very active on October 16-17 but must have lost some of its complexity before rotating into view.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4826 [S13E26] was quiet and stable.
New region S4831 [N09E07] emerged with a tiny spot.
New region S4832 [N11E21] was observed with tiny spots.
New region S4833 [N18E50] was observed with a tiny spot.
New region S4834 [N09W03] emerged with  tiny spot.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
           

Flare activity (SDO/EVE/ESP XRS-B proxy)

Coronal mass ejections (CMEs)

October 16-18: No obviously Earth directed CMEs were observed in available LASCO 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 northern hemisphere coronal hole (CH696) was in an Earth facing position on October 17-18.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over 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 to unsettled on October 19. Quiet to active is possible on October 20-21 due to effects from CH696.

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: 0-30% 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 overlays
Comment
SWPC Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12430 2015.10.07
2015.10.08
      S17W76            
12432 2015.10.09
2015.10.11
      S21W52          
S4808 2015.10.09       S10W57            
12431 2015.10.10 2 4 2 S19W30 0010 CAO CRO

location: S18W28

area: 0020

S4811 2015.10.10       N15W49            
12434 2015.10.13 11 45 17 S10E06 0220 DAI DSI beta-gamma-delta

area: 0330

S4819 2015.10.15       S12W08            
S4820 2015.10.15       S10W35            
12435 2015.10.16 1 3 1 S15E45 0030 HAX HAX  
12436 2015.10.16
2015.10.17
16 29 17 N09E58 0210 EAI EAC beta-gamma

area: 0380

S4824 2015.10.16       N03W17            
S4825 2015.10.16       N03W58            
S4826 2015.10.17   1 1 S13E25 0010   AXX  
S4827 2015.10.17       N22E10          
S4828 2015.10.17       S18W02          
S4829 2015.10.17       N12W24          
12437 2015.10.18 1 7 4 S19E74 0060 HAX CAO   location: S20E72

area: 0130

S4831 2015.10.18   1 1 N09E07 0003   AXX    
S4832 2015.10.18   4 2 N11E21 0006   BXO    
S4833 2015.10.18   1   N18E50 0001   AXX    
S4834 2015.10.18   1 1 N09W03 0003   AXX    
Total spot count: 31 96 46  
Sunspot number: 81 196 136  (total spot count + 10 * number of spotted regions)
Weighted SN: 56 119 69  (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): 89 108 116 k * (sunspot number)
As of July 1, 2015: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.85 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO) (4)
Smoothed sunspot number (4) Average ap
(3)
Measured 1 AU
2014.02 170.3
(cycle peak)
166.3 146.1 (cycle peak) 110.5 (+1.2) 10.70
2014.04 143.9 144.8 112.5 116.4 (+2.1) (solar max) 7.88
2014.08 124.7 127.9 106.9 108.3 (-4.3) 7.71
2014.09 146.6 148.1 130.0 101.9 (-6.4) 9.78
2014.10 153.4 152.9 90.0 97.3 (-4.6) 8.96
2014.11 154.8 151.4 103.6 94.7 (-2.6) 9.33
2014.12 158.7 153.8 112.9 92.2 (-2.5) 11.24
2015.01 141.9 137.3 93.0 89.3 (-2.9) 9.46
2015.02 129.1 126.0 66.7 86.1 (-3.2) 9.92
2015.03 125.9 124.6 54.5 82.2 (-3.9) 16.14
2015.04 128.8 129.7 75.3 (78.7 projected, -3.5) 10.73
2015.05 120.0 122.6 88.8 (75.9 projected, -2.8) 8.29
2015.06 122.3 126.1 66.5 (72.2 projected, -3.7) 13.15
2015.07 107.0 110.8 66.4 (68.5 projected, -3.7) 8.83
2015.08 105.4 108.0 64.6 (67.3 projected, -1.2) 14.58
2015.09 101.7 102.7 78.1 (67.6 projected, +0.3) 15.78
2015.10 (95.6)   25.7 (2A) / 44.3 (2B) / 78.7 (2C) (66.7 projected, -0.9) (18.6)

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).
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.
4) Updated to new data set from WDC-SILSO on July 1, 2015

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 Universal Time. Comments and suggestions are always welcome.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.