The geomagnetic field was quiet to minor storm on August 28 due to effects associated with the August 23 full halo CME. The high latitude magnetometer at Andenes recorded quiet to major storm conditions.
Solar flux density measured at 20h UT on 2.8 GHz was 89.9 - increasing 15.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 78.00). The Potsdam WDC planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.3). Three hour interval K indices: 53331220 (planetary), 53432321 (Boulder), 65432531 (Andenes).
The background x-ray flux is at the class B2 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 4 active regions using 2K resolution (SN: 122) and in 4 active regions using 1K resolution (SN: 85) SDO/HMI images.
Region 12859 [N18W19] decayed slowly and quietly.
Region 12860 [S27W11] was very active during the first half of the
day producing M and C flares. There are at least 2 magnetic delta structures
in the northern trailing penumbra and further M class events are possible. The following C1 flares
were recorded: C1.7 at 12:50, C1.3 at 13:40, C1.6 at 14:16 and C1.4 at 16:43 UT.
Spotted regions not observed (or interpreted
differently) by SWPC:
S7052 [S18E24] was quiet and stable.
New region S7053 [S27W68] emerged to the east of AR 12862.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
| C7.0 | 05:05 | S31E07 | 12860 | GOES16 | weak type II radio sweep |
| M4.7/1N | 06:11 | S28W01 | 12860 | GOES16 | LDE, partial halo CME weak type II and IV radio sweeps |
| M1.1 | 06:52 | 12860 | Learmonth | ||
| C4.2 | 08:46 | S26W01 | 12860 | GOES16 | |
| C4.6 | 10:17 | S29W02 | 12860 | San Vito | |
| C2.7 | 11:55 | S27W04 | 12860 | GOES16 |
August 28: A faint partial halo CME was observed in LASCO imagery
following the M4.7 flare in AR 12860. The CME could reach Earth on August
31.
August 27: No obviously Earth directed CMEs
were observed in available LASCO imagery.
August 26: A faint full halo CME was observed after a C3 flare in AR
12859 and
an associated erupting filament. The CME will likely reach Earth on August 29.
[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]
No obvious coronal holes are currently in or near Earth facing positions.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to minor storm on August 29-31 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.
(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 | ||||||||||
| S7040 | 2021.08.18 | S25W44 | |||||||||
| 12859 | 2021.08.20 2021.08.21 |
7 | 11 | 4 | N18W18 | 0040 | CAO | CRO |
 |
 |
|
| S7044 | 2021.08.23 | N31W40 | |||||||||
| 12860 | 2021.08.24 2021.08.24 |
27 | 65 | 36 | S29W10 | 0340 | EKI | EKC |
 |
 |
location: S27W11 area: 0600 beta-gamma-delta |
| S7048 | 2021.08.24 | N23W20 | |||||||||
| 12861 | 2021.08.25 2021.08.26 |
1 | N16E28 | 0010 | AXX |
 |
spotless | ||||
| S7050 | 2021.08.26 | N22E06 |
 |
||||||||
| 12862 | 2021.08.26 2021.08.27 |
2 | S28W81 | 0010 | BXO |
 |
spotless | ||||
| S7052 | 2021.08.26 | 2 | 2 | S18E24 | 0008 | CRO |
 |
 |
|||
| S7053 | 2021.08.28 | 4 | 3 | S27W68 | 0015 | BXO |
 |
||||
| Total spot count: | 37 | 82 | 45 | ||||||||
| Sunspot number: | 77 | 122 | 85 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 52 | 98 | 61 | (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): | 85 | 67 | 68 | ||||||||
| 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) |
| 2019.11 | 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 |
| 2020.02 | 71.0 | 69.3 | 0.4 | 2.7 (+0.5) | 6.16 |
| 2020.03 | 70.2 | 69.5 | 1.5 | 3.0 (+0.3) | 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 | 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 | (19.8 projected, +2.5) | 9.50 |
| 2021.03 | 76.0 | 75.2 | 17.3 | (23.2 projected, +3.4) | 10.17 |
| 2021.04 | 75.9 | 76.4 | 24.5 | (27.3 projected, +4.1) | 8.40 |
| 2021.05 | 75.3 | 77.1 | 21.2 | (30.0 projected, +2.7) | 6.50 |
| 2021.06 | 79.4 | 81.8 | 25.3 | (33.2 projected, +3.2) | 5.52 |
| 2021.07 | 81.0 | 83.6 | 34.4 | (37.8 projected, +4.6) | 5.51 |
| 2021.08 | 76.7 (1) | 18.5 (2A) / 20.5 (2B) / 26.3 (2C) | (42.5 projected, +4.7) | (6.0) | |
| 2021.09 | (48.2 projected, +5.7) | ||||
| 2021.10 | (52.6 projected, +4.4) | ||||
| 2021.11 | (57.2 projected, +4.6) | ||||
| 2021.12 | (63.0 projected, +5.8) | ||||
| 2022.01 | (66.6 projected, +3.6) | ||||
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.
