Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 30, 2021 at 10:00 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 (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 quiet on December 29. The high latitude magnetometer at Andenes recorded quiet to unsettled levels. A low speed stream associated with CH1051 began to influence the field late in the day.

Solar flux density measured at 20h UT on 2.8 GHz was 111.4 - increasing 24.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 81.66). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.8). Three hour interval K indices: 12111212 (planetary), 13122222 (Boulder), 32112233 (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 8 active regions using 2K resolution (SN: 174) and in 5 active regions using 1K resolution (SN: 96) SDO/HMI images.

Region 12916 [S17W21] decayed slightly until late in the day when a negative polarity patch and several spots emerged to the east of the trailing spots.
Region 12917 [S27W61] decayed slowly and quietly.
Region 12918 [N19W41] decayed slowly and was mostly quiet.
Region 12919 [S12E13] was quiet and stable.
Region 12920 [S17W74] decayed slowly and quietly.
Region 12921 [N30W75] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC:
S7265 [S20W41] decayed slowly and quietly.
New region S7269 [N18E13] was observed with tiny spots in an old plage area.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
C4.6 04:28   12916 GOES16  

Coronal mass ejections (CMEs)

December 27-29: 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 recurrent trans equatorial coronal hole (CH1051) was Earth facing on December 25-26. A recurrent northern hemisphere coronal hole (CH1052) was in an Earth facing position on December 28-29.

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 to good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 30 due to effects from CH1051 and quiet on December 31. On January 1-2 quiet to active conditions are likely due to effects from CH1052.

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
12914 2021.12.18
2021.12.21
      S17W89           location: S18W80
12912 2021.12.18
2021.12.19
      S13W69          

location: S14W63

12915 2021.12.18
2021.12.21
      N16W72            
12916 2021.12.21
2021.12.21
14 36 19 S17W22 0420 EHI EAC

beta-gamma

location: S17W21

S7253 2021.12.21       N24W40            
12918 2021.12.21
2021.12.22
10 37 18 N19W40 0210 CRI DRI

location: N19W41

area: 0100

12917 2021.12.21
2021.12.22
1 3 2 S26W62 0010 AXX CRO

location: S27W61

12920 2021.12.22
2021.12.26
  1   S17W70 0002   AXX location: S17W74
S7258 2021.12.24       N19W58            
12919 2021.12.24
2021.12.25
1 5 2 S11E12 0020 HRX CRO area: 0030
12921 2021.12.26
2021.12.28
3 9 5 N29W78 0180 DSO ESO area: 0280

location: N30W75

S7263 2021.12.26       N24W02          
S7264 2021.12.26       S18W39            
S7265 2021.12.26   1   S20W41 0001   AXX  
S7266 2021.12.27       S09W35            
S7267 2021.12.27       S34W27            
S7268 2021.12.28       S06E02          
S7269 2021.12.29   2   N18E13 0003   AXX    
Total spot count: 29 94 46  
Sunspot number: 79 174 96  (total spot count + 10 * number of spotted regions)
Weighted SN: 50 113 65  (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): 87 96 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 (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
2021.12 103.0 (1)   65.2 (2A) / 69.7 (2B) / 77.8 (2C) (55.1 projected, +5.8) (6.6)
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.