Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 27, 2021 at 14:20 UT.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data since 2003.01 (October 3, 2021)
Solar cycle Solar cycles 23-25 (October 1, 2021) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (October 1, 2021) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (June 1, 2020) POES auroral activity level October 2009 - December 2012]
  Comparison of cycles 21-25 (October 1, 2021) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (October 1, 2021) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (August 22, 2021) Cycle 25 spots (final update December 25, 2019)
  Solar cycles 24-25 transition using 365d smoothing Research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing

Recent activity

The geomagnetic field was quiet on October 26. The high latitude magnetometer at Andenes recorded quiet to active conditions.

Solar flux density measured at 20h UT on 2.8 GHz was 109.3 - increasing 7.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 80.39). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0). Three hour interval K indices: 12110002 (planetary), 21012212 (Boulder), 22000004 (Andenes).

The background x-ray flux is at the class B6 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 215) and in 7 active regions using 1K resolution (SN: 136) SDO/HMI images.

Region 12886 [S18W40] was quiet and stable.
Region 12887 [S23E14] was quiet and stable.
Region 12888 [S13E40] was quiet and stable.
Region 12889 [S23E45] developed slowly and quietly.
Region 12890 [S18W23] decayed slowly and quietly.
New region 12891 [N18E80] rotated into view producing many C flares and 2 minor M class events. C1 flares: C1.9 @ 00:19 UT (wrongly attributed to AR 12887 by SWPC), C1.9 @ 05:25, C1.3 @ 07:13. C1.8 @ 14:40, C1.1 @ 19:45 UT.

Spotted regions not observed (or interpreted differently) by SWPC:
S7142 [S27E18] developed a magnetic delta structure in the southernmost spot section. C and minor M class flares are possible.
New region S7155 [N33E08] emerged with tiny spots.
New region S7156 [N13E11] emerged with a tiny spot.
New region S7157 [S23E29] emerged with tiny spots.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
C9.3 01:04 S18E90 12891 GOES16  
C3.5 01:50   12891 GOES16 wrongly attributed to AR 12889 by SWPC
M1.3 02:47 S18E90 12891 GOES16  
C2.0 03:24   12891 GOES16 wrongly attributed to AR 12889 by SWPC
C2.3 04:33   12891 GOES16 wrongly attributed to AR 12889 by SWPC
C7.8 06:04   12891 GOES16 wrongly attributed to AR 12887 by SWPC. There was a simultaneous event in AR S7142, but smaller than the one in AR 12891
C5.0 09:52   12891 GOES16  
C4.8 11:25   12891 GOES16  
C2.0 11:49   12891 GOES16  
C3.1 13:38   12891 GOES16  
M1.0 15:57 S18E87 12891 GOES16  
C2.1 23:10   12891 GOES16  

Coronal mass ejections (CMEs)

October 24-26: 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]

No obvious coronal holes are currently in or near Earth facing positions.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet on October 27-30.

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). 4K 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 officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. 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. SWPC data considered to be not sufficiently precise (location, area, classification) are red colored.

Active region SWPC date numbered
STAR detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlays
Comment
SWPC/
USAF
Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12886 2021.10.17
2021.10.18
1 3 1 S20W41 0100 HSX CSO

location: S18W40

S7136 2021.10.19       N23W26            
S7139 2021.10.20       S31W50            
12887 2021.10.21
2021.10.22
20 25 14 S26E15 0370 DHI CAO

location: S23E14

area: 0220

SWPC data includes AR S7142

S7142 2021.10.21   47 31 S27E18 0270   DAC beta-gamma-delta
S7143 2021.10.22       S13W10            
S7144 2021.10.22       N14W08            
S7145 2021.10.23       S24W15            
12888 2021.10.23
2021.10.24
1 3 1 S13E39 0010 AXX HRX location: S13E40
12889 2021.10.24
2021.10.25
4 18 11 S23E43 0020 BXO DRI location: S23E45

area: 0060

S7148 2021.10.24       N21E09            
S7149 2021.10.24       N01E04            
12890 2021.10.25
2021.10.25
5 11 7 S18W23 0040 CRO DRI area: 0060
S7151 2021.10.25       N14E10          
S7152 2021.10.25       S34W10          
S7153 2021.10.25       S21W56          
12891 2021.10.26
2021.10.26
4 4 3 N20E78 0280 DSO CAO   location: N18E80

area: 0140

S7155 2021.10.26   2   N33E08 0003   BXO    
S7156 2021.10.26   1   N13E11 0002   AXX    
S7157 2021.10.26   1   S23E27 0001   AXX    
Total spot count: 35 115 68  
Sunspot number: 95 215 138  (total spot count + 10 * number of spotted regions)
Weighted SN: 58 144 97  (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): 105 118 110  

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number (4) Average ap
(3)
Measured 1 AU
2014.02 170.3
(cycle peak)
166.3 146.1 (cycle peak) 110.5 10.70
2014.04 143.9 144.8 112.5 116.4 (solar max) 7.88
2017.09 91.3 92.3 43.6 18.2 (-1.3) 18.22
(cycle peak)
2019.11 70.2 68.7 0.5 2.0 (-0.6)
(Solar minimum using 365d smoothing:
November 17, 2019)
4.19
2019.12 70.8 68.6 1.6 1.8 (-0.2)
(ISN 13 months smoothed
solar minimum)
3.22
2020.04 69.5 70.0 5.4 3.6 (+0.6) 5.32
2020.05 69.0 70.6 0.2 5.6 (+2.0) 3.80
2020.06 69.5 71.7 5.8 7.9 (+2.3) 3.75
2020.07 69.5 71.8 6.3 9.0 (+1.1) 4.28
2020.08 71.6 73.4 7.6 9.5 (+0.5) 5.68
2020.09 70.7 71.4 0.7 10.5 (+1.0) 8.59
2020.10 74.6 74.2 14.6 11.9 (+1.4) 6.13
2020.11 89.9 88.0 34.5 13.6 (+1.7) 4.77
2020.12 86.9 84.2 23.1 15.3 (+1.7) 4.72
2021.01 76.0 73.6 10.4 17.3 (+2.0) 4.39
2021.02 74.3 72.4 8.3 19.1 (+1.8) 9.50
2021.03 76.0 75.2 17.3 21.8 (+2.7) 10.17
2021.04 75.9 76.4 24.5 (26.0 projected, +4.2) 8.40
2021.05 75.3 77.1 21.2 (28.7 projected, +2.7) 6.50
2021.06 79.4 81.8 25.3 (31.9 projected, +3.2) 5.52
2021.07 81.0 83.6 34.4 (36.5 projected, +4.6) 5.51
2021.08 77.7 79.7 22.4 (41.1 projected, +4.6) 6.19
2021.09 87.0 88.2 51.5 (46.8 projected, +5.7) 6.33
2021.10 85.2 (1)   22.8 (2A) / 27.2 (2B) / 40.0 (2C) (51.2 projected, +4.4) (7.6)
2021.11       (55.8 projected, +4.6)  
2021.12       (61.7 projected, +5.9)  
2022.01       (65.3 projected, +3.6)  
2022.02       (70.0 projected, +4.7)  
2022.03       (75.4 projected, +5.4)  

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz and any corrections applied to that measurement.
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) Source: SIDC-SILSO.

Solar cycles 24-25

Smoothed SF and sunspot numbers

 

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.