Solar Terrestrial Activity Report

Activity chart

Last major update issued on November 2, 2021 at 18:05 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 to active on November 1. The high latitude magnetometer at Andenes recorded quiet to active levels. Solar wind speed and temperature increased slowly after 16h UT at DSCOVR and another disturbance started. The source of the disturbance is uncertain, solar wind parameters suggest a coronal hole source.

Solar flux density measured at 20h UT on 2.8 GHz was 97.7 - increasing 16.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 80.74). The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.1). Three hour interval K indices: 23121133 (planetary), 23221233 (Boulder), 43211233 (Andenes).

The background x-ray flux was at the class B4 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 8 active regions using 2K resolution (SN: 125) and in 7 active regions using 1K resolution (SN: 96) SDO/HMI images.

Region 12887 [S25W64] was quiet and stable. Note that SWPC includes AR S7142 in this region.
Region 12888 [S13W37] was quiet and stable.
Region 12891 [N16E02] decayed slightly and could produce M class flares. The region was the source of a bright M1.7 long duration event peaking at 03:00 UT on November 2. This flare was associated with a full halo CME.
Region 12892 [N27W41] decayed slowly and quietly.
Region 12893 [N15E59] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC:
S7142 [S30W57] decayed slowly but was still capable of producing C and M flares. Two of the flares were associated with at least partial halo CMEs, however, given the location of the region, the CME from AR 12891 could easily catch up with those two before they reach Earth. C1 flares: C1.3 @ 18:01 UT
S7165 [S22W13] decayed slowly and quietly.
New region S7167 [N28W09] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
M1.5/1F 01:45 S29W45 S7142 GOES16 partial halo CME, weak type II and moderate type IV radio sweeps
C2.1 20:44 N16E11 12891 GOES16  
C4.0 21:33 S29W62 S7142 GOES16 partial halo CME
C4.5 23:40   S7142 GOES16  

Coronal mass ejections (CMEs)

October 30-31: No obviously Earth directed CMEs were observed in available LASCO imagery.
November 1: Partial halo CMEs were observed after flares in AR S7142 peaking at 01:45 and 21:33 UT. The CMEs could reach Earth on November 4.
November 2: A fast full halo CME was observed after the M1.7 LDE in AR 12891 at 03:00 UT. The flare occurred while the region was crossing the central meridian and the CME is aimed almost directly at Earth. Active to severe storm conditions are possible on November 4.

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

Forecast

The geomagnetic field is expected to be quiet to unsettled on November 2-3 and quiet to severe storm on November 4-5 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
12887 2021.10.21
2021.10.22
5 1 1 S27W64 0160 CSO HSX

location: S25W64

area: 0100

SWPC data includes AR S7142

S7142 2021.10.21   4 2 S30W57 0010   BXO  
12888 2021.10.23
2021.10.24
  2 1 S12W43 0005   AXX location: S13W37
12889 2021.10.24
2021.10.25
      S24W35         location: S27W32
12891 2021.10.26
2021.10.26
17 33 19 N16E03 0230 DAI DAI beta-gamma-delta
S7157 2021.10.26       S23W51            
S7159 2021.10.28       N24W03            
12892 2021.10.29
2021.10.30
  2 1 N26W43 0004   AXX  
S7162 2021.10.29       S19W24            
S7163 2021.10.29       S04W47            
12893 2021.10.30
2021.10.31
1 1 1 N15E57 0180 HSX HSX  
S7165 2021.10.30   1   S22W13 0001   AXX  
S7166 2021.10.31       N23W34          
S7167 2021.11.01   1 1 N28W09 0003   AXX    
Total spot count: 23 45 26  
Sunspot number: 53 125 96  (total spot count + 10 * number of spotted regions)
Weighted SN: 38 60 41  (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): 58 69 77  

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
2020.05 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 24.9 (+3.1) 8.40
2021.05 75.3 77.1 21.2 (26.6 projected, +1.7) 6.50
2021.06 79.4 81.8 25.3 (29.8 projected, +3.2) 5.52
2021.07 81.0 83.6 34.4 (34.4 projected, +4.6) 5.51
2021.08 77.7 79.7 22.4 (39.1 projected, +4.7) 6.19
2021.09 87.0 88.2 51.5 (44.8 projected, +5.7) 6.33
2021.10 88.9 88.3 38.1 (49.1 projected, +4.3) 7.3
2021.11 97.7 (1)   1.8 (2A) / 53 (2B) / 47.1 (2C) (53.7 projected, +4.6) (8.1)
2021.12       (59.6 projected, +5.9)  
2022.01       (63.2 projected, +3.6)  
2022.02       (67.9 projected, +4.7)  
2022.03       (73.4 projected, +5.5)  
2022.04       (78.5 projected, +5.1)  

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.