Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 8, 2020 at 06:25 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, 2020)
Solar cycle Solar cycles 23-25 (December 1, 2020) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (December 1, 2020) 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, 2020) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (December 1, 2020) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (July 6, 2020) Cycle 25 spots (final update December 25, 2019)
  Solar cycles 24-25 using 365d smoothing (*) Recent research
    Current research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing

Recent activity

The geomagnetic field was very quiet on December 7. The high latitude magnetometer at Andenes recorded inactive conditions.

Solar flux at 20h UT on 2.8 GHz was 89.5 - increasing 2.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU: Minimum of 69.13 on November 17, 2019. Current: 72.86). The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.4). Three hour interval K indices: 00110100 (planetary), 10111110 (Boulder), 00000000 (Andenes).

The background x-ray flux is at the class B1 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 2 active regions using 2K resolution (SN: 42) and in 2 active regions using 1K resolution (SN: 25) SDO/HMI images.

Region 12790 [S22W14] produced a long duration C7.4 event which was associated with an asymmetric full halo CME in LASCO C3 imagery. The initial estimate is that the CME could reach Earth on December 10.
Region 12791 [S16E16] decayed slowly and quietly.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
C7.4 16:32 S25W04 12790 GOES16 asymmetric full halo CME

Coronal mass ejections (CMEs)

December 5-6: No obviously Earth directed CMEs were observed in available LASCO imagery.
December 7: An asymmetric full halo CME was observed after a C7.4 in AR 12790 at 16:32 UT. The CME could reach Earth on December 10 and cause unsettled to minor storm conditions.

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 (CH981) rotated across the central meridian on December 5-7.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is good (with the exception of polar paths which are still affected by slightly enhanced proton levels). Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on December 8 becoming quiet to unsettled on December 9-11 due to effects from CH981. Unsettled to minor storm conditions are possible on December 10-11 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
12787 2020.11.26
2020.11.27
      N30W74          

location: N33W59

12789 2020.11.28
2020.11.29
      S25W69           location: S26W55
12790 2020.11.30
2020.12.01
1 13 3 S22W15 0050 HSX CSO

area: 0120

S6641 2020.12.01       S18W46            
S6642 2020.12.02       S41W28            
S6643 2020.12.03       S13W25            
12791 2020.12.03
2020.12.05
2 9 2 S15E15 0010 AXX BXO

 

S6646 2020.12.04       N19W22            
Total spot count: 3 22 5  
Sunspot number: 23 42 25  (total spot count + 10 * number of spotted regions)
Weighted SN: 8 27 10  (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): 25 23 20 k * (sunspot number)
As of May 7, 2016: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.80 for MSN 1K (MSN=Magnetic Sunspot Number)

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)
2019.06 68.1 70.3 1.2 3.7 (-0.2) 4.26
2019.07 67.1 69.3 0.9 3.5 (-0.2) 5.36
2019.08 67.0 68.7 0.5 3.4 (-0.1) 6.79
2019.09 67.9 68.7 1.1 3.1 (-0.3) 9.81
2019.10 67.4 67.0 0.4 2.6 (-0.5) 7.53
2019.11 70.2 68.7 0.5 2.0 (-0.6)
(November 17, 2019 is
the solar minimum using 365d
smoothing for 1 AU solar flux,
NOAA SN and both
of STAR 1K and 2K SN)
4.19
2019.12 70.8 68.6 1.6 1.8 (-0.2)
(ISN 13 months smoothed
solar minimum)
3.22
2020.01 72.2 69.9 6.4 2.2 (+0.4) 4.39
2020.02 71.0 69.3 0.4 2.8 (+0.6) 6.16
2020.03 70.2 69.5 1.5 3.0 (+0.2) 5.63
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 (8.1 projected, +2.5) 3.75
2020.07 69.5 71.8 6.3 (9.9 projected, +1.8) 4.28
2020.08 71.6 73.4 7.6 (12.3 projected, +2.4) 5.68
2020.09 70.7 71.4 0.7 (16.2 projected, +3.9) 8.59
2020.10 74.6 74.2 14.4 (19.5 projected, +3.3) 6.13
2020.11 89.9 88.0 34.0 (22.3 projected, +2.8) 5.0
2020.12 (98.3) (1)    8.2 (2A) / 36.4 (2B) / 33.4 (2C) (26.3 projected, +4.0) (2.3)
2021.01       (30.6 projected, +4.3)  
2021.02       (34.3 projected, +3.7)  
2021.03       (39.3 projected, +5.0)  
2021.04       (45.2 projected, +5.9)  
2021.05       (49.6 projected, +4.4)  

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
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 transition

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.