The geomagnetic field was inactive on December 4. The high latitude magnetometer at Andenes recorded inactive conditions.
Solar flux at 20h UT on 2.8 GHz was 95.8 - increasing 5.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU: Minimum of 69.13 on November 17, 2019. Current: 72.68). The Potsdam WDC planetary A index was 0 (STAR Ap - based on the mean of three hour interval ap indices: 0.0). Three hour interval K indices: 00000000 (planetary), 00001110 (Boulder), 00000000 (Andenes).
The background x-ray flux is at the class B3 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 6 active regions using 2K resolution (SN: 97) and in 3active regions using 1K resolution (SN: 41) SDO/HMI images.
Region 12786 [S16W69] decayed slowly and
quietly.
Region 12787 [N33W20] was quiet and stable.
Region 12789 [S26W16] was quiet and stable.
Region 12790 [S22E24] decayed slowly. A long
duration C1.6 event peaked at 00:36 UT on December 5. This event was
associated with a filament eruption to the north of the region. LASCO
imagery covering the hours after this event is not available as this is
written. There is a chance a CME was produced.
Spotted regions not observed (or interpreted
differently) by SWPC:
S6644 [S16E57] developed adding quite a few
spots. Further development is likely.
New region S6646 [N19E17] emerged with tiny spots.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
December 2-4: No obviously Earth directed CMEs were observed in available LASCO imagery.
[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 small recurrent trans equatorial coronal (CH981) could rotate across the central meridian on December 5.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on December 5-8 becoming quiet to unsettled on December 9 due to effects from CH981.
| 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.
(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 | ||||||||||
| 12785 | 2020.11.22 2020.11.22 |
1 | S23W88 | 0120 | HSX |
 |
rotated out of view |
||||
| 12786 | 2020.11.22 2020.11.23 |
3 | 8 | 3 | S17W71 | 0460 | HKX | CKO |
 |
 |
|
| 12787 | 2020.11.26 2020.11.27 |
5 | N30W32 | 0005 | BXO |
 |
 |
location: N33W20 |
|||
| 12789 | 2020.11.28 2020.11.29 |
2 | S25W27 | 0002 | BXO |
 |
 |
location: S26W16 | |||
| 12790 | 2020.11.30 2020.12.01 |
4 | 9 | 3 | S23E24 | 0100 | CAO | CAO |
 |
 |
area: 0140 |
| S6640 | 2020.11.30 | N09W44 | |||||||||
| S6641 | 2020.12.01 | S18W07 | |||||||||
| S6642 | 2020.12.02 | S41E11 | |||||||||
| S6643 | 2020.12.03 | S13E14 |
 |
||||||||
| S6644 | 2020.12.03 | 11 | 5 | S16E57 | 0025 | BXI |
 |
 |
|||
| S6646 | 2020.12.04 | 2 | N19E17 | 0004 | BXO |
 |
|||||
| Total spot count: | 8 | 37 | 11 | ||||||||
| Sunspot number: | 38 | 97 | 41 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 28 | 52 | 26 | (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): | 42 | 53 | 33 | 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) |
|||||||
| 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 | (101.9) (1) | 5.3 (2A) / 41.3 (2B) / 34.9 (2C) | (26.3 projected, +4.0) | (1.4) | |
| 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.
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.
