The next update is scheduled for the afternoon of December 27. Then the plan is to produce 2 updates a day (one update for each day during Christmas as there is a lot of data to process with the currently active Sun) and be up to date on December 29.
The geomagnetic field was quiet on December 23. The high latitude magnetometer at Andenes recorded quiet to active levels.
Solar flux density measured at 20h UT on 2.8 GHz was 129.8 - increasing 37.5 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 81.09). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.6). Three hour interval K indices: 20010011 (planetary), 11111221 (Boulder), 40000031 (Andenes).
The background x-ray flux is at the class B8 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 271) and in 10 active regions using 1K resolution (SN: 165) SDO/HMI images.
Region 12907 [S20W65] developed further and
could produce M class events. Many small C flares were recorded during the
day.
C1 flares: C1.4 @ 00:58, C1.1 @ 02:23, C1.7 @ 03:30, C1.4 @ 14:01, C1.1 @
15:01, C1.0 @ 16:19, C1.2 @ 17:41, C1.1 @ 18:49, C1.2 @ 22:03, C1.3 @ 23:35 UT.
Region 12909 [S20W38] decayed slowly and quietly.
Region 12911 [N21W22] was quiet and stable.
Region 12912 [S11E14] decayed slowly and quietly.
Region 12915 [N17E12] developed slowly and quietly.
Region 12916 [S17E54] was mostly quiet and stable. There is a chance of M
class flaring. C1 flares: C1.4 @ 12:46 UT.
Region 12917 [S27E19] developed and produced a C7 flare early on
December 24. The region has weak polarity intermixing. C1 flares: C1.4
@ 13:22 UT.
Region 12918 [N20E40] displayed no major changes. C1 flares: C1.3 @ 20:46 UT.
Spotted regions not observed (or interpreted
differently) by SWPC:
S7239 [S18W52] decayed slowly and quietly. SWPC
includes these spots in AR 12908.
S7256 [S19E09] was quiet and stable.
New region S7257 [S26W01] was observed with tiny spots in an
old plage area.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
| C2.0 | 07:32 | S23W57 | 12907 | GOES16 | |
| C2.1 | 08:11 | S21W58 | 12907 | GOES16 | |
| C2.6 | 09:30 | S20W57 | 12907 | GOES16 |
December 21-23: 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]
An extension (CH1050) of the northern polar coronal hole will rotate across the central meridian on December 24.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on December 24-26.
| 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 | ||||||||||
| 12907 | 2021.12.12 2021.12.13 |
17 | 35 | 18 | S22W65 | 0300 | EKI | EKI |
 |
 |
beta-gamma location: S20W65 area: 0450 |
| 12908 | 2021.12.14 2021.12.15 |
10 | S20W52 | 0100 | CAI |
 |
SWPC data includes AR S7239 spotless |
||||
| 12909 | 2021.12.14 2021.12.15 |
2 | 11 | 4 | S21W39 | 0050 | HAX | CRO |
 |
 |
location: S20W38 area: 0030 |
| S7239 | 2021.12.15 | 17 | 8 | S18W52 | 0050 | CRI |
 |
 |
|||
| 12911 | 2021.12.16 2021.12.16 |
1 | 11 | 1 | N20W25 | 0010 | AXX | BXO |
 |
 |
area: 0015 location: N21W22 |
| 12913 | 2021.12.17 2021.12.20 |
S28W08 | |||||||||
| 12914 | 2021.12.18 2021.12.21 |
S17W04 | |||||||||
| 12912 | 2021.12.18 2021.12.19 |
1 | 7 | 3 | S12E13 | 0010 | HRX | CRO |
 |
 |
area: 0030 |
| S7246 | 2021.12.18 | N15W58 | |||||||||
| 12915 | 2021.12.18 2021.12.21 |
2 | 11 | 4 | N17E10 | 0030 | CRO | DRO |
 |
 |
area: 0040 |
| S7248 | 2021.12.18 | S10W39 | |||||||||
| S7250 | 2021.12.20 | S21W22 | |||||||||
| 12916 | 2021.12.21 2021.12.21 |
7 | 16 | 6 | S16E55 | 0190 | DSO | EHO |
 |
 |
area: 0500 location: S17E54 |
| S7252 | 2021.12.21 | N19E21 |
 |
||||||||
| S7253 | 2021.12.21 | N24E38 | |||||||||
| 12918 | 2021.12.21 2021.12.22 |
6 | 23 | 9 | N20E40 | 0080 | DAO | DSI |
 |
 |
area: 0200 |
| 12917 | 2021.12.21 2021.12.22 |
7 | 21 | 10 | S27E18 | 0030 | CRO | DAI |
 |
 |
beta-gamma area: 0130 |
| S7256 | 2021.12.22 | 6 | 2 | S19E09 | 0010 | BXO |
 |
 |
|||
| S7257 | 2021.12.23 | 3 | S26W01 | 0004 | AXX |
 |
|||||
| Total spot count: | 53 | 161 | 65 | ||||||||
| Sunspot number: | 143 | 271 | 165 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 92 | 203 | 107 | (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): | 157 | 149 | 132 | ||||||||
| 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 | 97.8 (1) | 45.0 (2A) / 60.6 (2B) / 65.4 (2C) | (55.1 projected, +5.8) | (6.8) | |
| 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.
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.
