Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 17, 2021 at 07:35 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 to unsettled on December 16 due to effects from CH1048. The high latitude magnetometer at Andenes recorded quiet to unsettled levels.

Solar flux density measured at 20h UT on 2.8 GHz was 117.9 - increasing 38.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 80.27). The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.9). Three hour interval K indices: 23321122 (planetary), 12331221 (Boulder), 33322333 (Andenes).

The background x-ray flux is at the class B9 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 251) and in 8 active regions using 1K resolution (SN: 165) SDO/HMI images.

Region 12905 [S11W10] decayed slowly and quietly.
Region 12906 [S29W02] was quiet and stable.
Region 12907 [S21E27] was much less active than during the previous days and appears to have peaked in its development. C1 flares: C1.5 @ 05:21 UT.
Region 12908 [S21E42] developed further and was quiet.
Region 12909 [S21E54] developed slowly and produced several C flares. C1 flares: C1.4 @ 03:34, C1.3 @ 03:54 UT.
New region 12910 [N14W13] emerged on December 11 and was numbered by SWPC 5 days later.
New region 12911 [N19E68] emerged with spots before noon and developed fairly quickly. Opposite polarity spots were closely separated near the center of the region and an M1.2 flare was recorded at 00:50 UT on December 17. The region is unstable and further development is likely. C1 flares: C1.4 @ 13:32 UT

Spotted regions not observed (or interpreted differently) by SWPC:
S7239 [S17E41] developed further and was quiet. SWPC has been unable to separate this region from AR 12908.
New region S7241 [N24W79] emerged near the northwest limb and developed quickly.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
C2.0/2F 13:41 N14E63 12911 GOES16 simultaneous flare in AR 12906
C3.3 15:27   12909 GOES16  
C2.3 20:09 N19E76 12911 GOES16  
C2.9 20:44   12911 GOES16  
C3.0 23:39 S23E61 12909 GOES16  

Coronal mass ejections (CMEs)

December 14-16: 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 trans equatorial coronal hole (CH1049) will rotate across the central meridian on December 17-19.

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 on December 17-19. Quiet to active conditions are expected for December 20-22 due to effects from CH1049.

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
S7227 2021.12.08       S17W49            
12910 2021.12.11
2021.12.16
6 15 6 N13W16 0020 CRO DRI area: 0060
12905 2021.12.11
2021.12.12
1 4   S12W11 0010 AXX BXO  
12907 2021.12.12
2021.12.13
23 40 28 S20E26 0180 DAI EAI beta-gamma

area: 0300

S7233 2021.12.12       S19W03            
S7234 2021.12.12       N32W51            
12906 2021.12.13
2021.12.13
9 23 9 S29W04 0060 CSO CSI location: S29W02
S7236 2021.12.13       N29W04            
12908 2021.12.14
2021.12.15
10 35 16 S20E43 0210 DAO DAI area: 0300
12909 2021.12.14
2021.12.15
5 14 8 S21E58 0150 DAO DAO area: 0220
S7239 2021.12.15   14 9 S17E41 0080   DSO  
12911 2021.12.16 3 12 7 N19E70 0020 CRO DRI   area: 0070

was AR S7240

S7241 2021.12.16   4 2 N24W79 0040   CRO    
Total spot count: 57 161 85  
Sunspot number: 127 251 165  (total spot count + 10 * number of spotted regions)
Weighted SN: 83 195 85  (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): 140 138 132  

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) 9.9
2021.12 85.2 (1)   16.4 (2A) / 31.7 (2B) / 39.7 (2C) (55.1 projected, +5.8) (6.1)
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.