Solar Terrestrial Activity Report

Activity chart

Last major update issued on November 1, 2021 at 17:30 UT (update for October 29)

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 very quiet on October 29. The high latitude magnetometer at Andenes recorded quiet to unsettled conditions.

Solar flux density measured at 20h UT on 2.8 GHz was 108.4 - increasing 21.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 80.59). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.6). Three hour interval K indices: 00000111 (planetary), 01100212 (Boulder), 00000013 (Andenes).

The background x-ray flux was at the class B3 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 200) and in 8 active regions using 1K resolution (SN: 124) SDO/HMI images.

Region 12886 [S18W80] was quiet and stable as it rotated to the southwest limb.
Region 12887 [S24W24] decayed slowly and quietly.
Region 12888 [S13E08] was quiet and stable.
Region 12889 [S24E07] decayed slowly and quietly.
Region 12891 [N17E42] regained a magnetic delta, and is still a compact region capable of producing M class flares. C1 flares: C1.5 @ 11:26 UT.

Spotted regions not observed (or interpreted differently) by SWPC:
S7142 [S28W20] decayed further and was considerably less active than on the previous day.
C1 flares: C1.1 @ 07:45 UT.
S7160 [N18W41] was quiet and stable.
New region S7161 [N27W02] emerged with several spots.
New region S7162 [S19E15] emerged with a tiny spot.
New region S7163 [S04W08] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
M1.5/1N 02:42 N16E54 12891 GOES16  
C4.8/1F 05:58 N17E53 12891 GOES16  
C2.5 13:30 S29W18 S7142 GOES16  

Coronal mass ejections (CMEs)

October 27, 29: No obviously Earth directed CMEs were observed in available LASCO imagery.
October 28: A large and fast asymmetric CME was observed after the X1 flare in AR S7142.

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]

An extension (CH1039) of the northern pole coronal hole will rotate across the central meridian on October 31.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet to severe 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: 0-30% 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 1 1 S19W81 0100 HSX HSX

 

12887 2021.10.21
2021.10.22
22 9 3 S26W21 0250 DHI CSO

location: S24W24

area: 0130

SWPC data includes AR S7142

S7142 2021.10.21   28 13 S28W20 0110   DRI beta-gamma
S7143 2021.10.22       S13W49            
S7144 2021.10.22       N14W47            
S7145 2021.10.23       S24W54            
12888 2021.10.23
2021.10.24
  4 1 S12W01 0006   BXO location: S13E08
12889 2021.10.24
2021.10.25
3 11 2 S23E03 0010 BXO BXO location: S24E07
S7148 2021.10.24       N21W30            
S7149 2021.10.24       N01W35            
12890 2021.10.25
2021.10.25
      S18W64          
S7151 2021.10.25       N14W29            
S7152 2021.10.25       S34W49            
12891 2021.10.26
2021.10.26
16 31 17 N17E41 0350 DKI DKC beta-gamma-delta
S7155 2021.10.26       N33W31            
S7156 2021.10.26       N13W28            
S7157 2021.10.26       S23W12            
S7158 2021.10.27       N37W30            
S7159 2021.10.28       N24E36          
S7160 2021.10.28   4 2 N19W41 0006   BXO  
S7161 2021.10.29   10 5 N27W02 0050   DRI    
S7162 2021.10.29   1   S19E15 0001   AXX    
S7163 2021.10.29   1   S04W08 0001   AXX    
Total spot count: 42 100 44  
Sunspot number: 82 200 124  (total spot count + 10 * number of spotted regions)
Weighted SN: 67 126 70  (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): 90 110 99  

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 87.8 (1)   33.9 (2A) / 36.3 (2B) / 42.5 (2C) (51.2 projected, +4.4) (7.0)
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.