Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 28, 2021 at 10:45 UT (for December 26)

The update for December 27 is scheduled for the evening of December 28.

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 (December 1, 2021)
Solar cycle Solar cycles 23-25 (December 1, 2021) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (December 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 (December 1, 2021) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (December 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 December 26. The high latitude magnetometer at Andenes recorded quiet to unsettled levels.

Solar flux density measured at 20h UT on 2.8 GHz was 125.4 - increasing 35.6 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 81.41). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.3). Three hour interval K indices: 10010011 (planetary), 01111221 (Boulder), 10000032 (Andenes).

The background x-ray flux was at the class C1 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 271) and in 11 active regions using 1K resolution (SN: 189) SDO/HMI images.

Region 12912 [S14W24] was quiet and stable.
Region 12915 [N16W29] decayed slowly and quietly.
Region 12916 [S17E18] decayed slightly and was mostly quiet. An M class flare is possible.
Region 12917 [S30W18] decayed slowly and was mostly quiet.
Region 12918 [N18E01] has many spots and M class flaring is possible. C1 flares: C1.8 @ 00:21 UT.
Region 12919 [S12E53] was quiet and stable.
New region 12920 [S18W30] emerged on December 22 and was numbered by SWPC 4 days later as the region developed fairly quickly. C1 flares: C1.4 @ 18:59 UT.

Spotted regions not observed (or interpreted differently) by SWPC:
S7258 [N19W18] reemerged with a few spots.
New region S7261 [N29W33] emerged before noon with tiny spots.
New region S7263 [N22E35] was observed with tiny spots in an old plage area.
New region S7264 [S18W00] emerged with tiny spots.
New region S7265 [S21E01] emerged with tiny spots.

AR S7239 behind the southwest limb produced a C1.8 flare at 01:35, a C1.0 flare at 18:32 UT and a C1.1 flare peaking at 00:02 UT on December 27.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
C2.6 00:36 behind SW limb S7239 GOES16  
C2.0 04:42   12918 GOES16  
C3.2 20:12   S7239 GOES16  

Coronal mass ejections (CMEs)

December 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]

An extension (CH1050) of the northern polar coronal hole rotated across the central meridian on December 24. A recurrent trans equatorial coronal hole (CH1051) was Earth facing on December 26. A recurrent northern hemisphere coronal hole (CH1052) could rotate into an Earth facing position on December 28.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 27-28 due to effects from CH1050 and quiet on December 29.

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
12909 2021.12.14
2021.12.15
      S21W81           location: S20W77
12911 2021.12.16
2021.12.16
      N20W67          

location: N21W63

12913 2021.12.17
2021.12.20
      S25W51            
12914 2021.12.18
2021.12.21
      S17W47         location: S18W41
12912 2021.12.18
2021.12.19
1 3 1 S13W27 0010 AXX AXX

 

12915 2021.12.18
2021.12.21
  3 1 N16W30 0005   AXX  
12916 2021.12.21
2021.12.21
17 44 23 S18E14 0430 EKC EHC

beta-gamma

area: 0600

location: S17E18

S7253 2021.12.21       N24W01            
12918 2021.12.21
2021.12.22
17 47 27 N19W03 0260 DKI DAI  
12917 2021.12.21
2021.12.22
  4 1 S28W20 0005   BXO

location: S30W18

12920 2021.12.22
2021.12.26
9 22 14 S17W31 0030 CRO DRI area: 0100
S7257 2021.12.23       S26W37            
S7258 2021.12.24   10 5 N19W18 0025   BXO    
12919 2021.12.24
2021.12.25
1 4 2 S11E45 0020 HRX HRX location: S12E53

area: 0030

S7261 2021.12.26   6 3 N29W33 0015   BXO    
S7262 2021.12.26       N32W32          
S7263 2021.12.26   2   N22E35 0002   BXO    
S7264 2021.12.26   4 1 S18W00 0008   BXO    
S7265 2021.12.26   2 1 S21E01 0008   HRX    
Total spot count: 45 151 79  
Sunspot number: 95 271 189  (total spot count + 10 * number of spotted regions)
Weighted SN: 71 175 103  (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): 105 149 151  

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 (SC24 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
2020.06 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 25.9 (+1.0) 6.50
2021.06 79.4 81.8 25.3 (26.9 projected, +1.0) 5.52
2021.07 81.0 83.6 34.4 (29.9 projected, +3.0) 5.51
2021.08 77.7 79.7 22.4 (34.6 projected, +4.7) 6.19
2021.09 87.0 88.2 51.5 (40.3 projected, +5.7) 6.33
2021.10 88.9 88.3 38.1 (44.7 projected, +4.4) 7.38
2021.11 86.2 84.4 35.1 (49.3 projected, +4.6) 9.83
2021.12 101.3 (1)   56.5 (2A) / 67.3 (2B) / 73.8 (2C) (55.1 projected, +5.8) (6.5)
2022.01       (58.7 projected, +3.6)  
2022.02       (63.5 projected, +4.8)  
2022.03       (68.9 projected, +5.4)  
2022.04       (74.0 projected, +5.1)  
2022.05       (80.4 projected, +6.4)  

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.