The geomagnetic field was quiet to active on August 27 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 89.5 - increasing 13.6 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 77.95). The Potsdam WDC planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 18.5). Three hour interval K indices: 31244334 (planetary), 313***** (Boulder), 30135656 (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: 149) and in 5 active regions using 1K resolution (SN: 98) SDO/HMI images.
Region 12859 [N18W06] decayed slowly and was
mostly quiet.
Region 12860 [S27E02] developed quickly in the northern spot section,
and a magnetic delta has formed in the trailing part of that area. A major
flare is possible. Apart from the long duration C7 event in the evening, the
region produced the following C flares: C1.0 at 13:12, C1.7 at 20:21, C1,2
at 23:28 and C1.2 at 23:59 UT.
Region 12861 [N16E38] decayed slowly and quietly.
New region 12862 [S28W66] emerged on August 26 and was numbered the
next day by SWPC. The region produced a C1.2 flare at 12:58, a C1.0 flare at
13:22 and a C1.1 at 15:14 UT.
Spotted regions not observed (or interpreted
differently) by SWPC:
S7050 [N22E19] decayed slowly and quietly.
S7052 [S18E38] developed slowly and quietly.
Minor update added at 06:20 UT on August 28:
AR 12860 produced an M4.7 flare peaking at 06:11 UT. It is not yet known if there was a CME associated with the event.
Minor update added at 06:20 UT on August 28:
A fast EIT wave was observed in SDO/AIA imagery during the long duration M4.7 flare. As the flare occurred near the central meridian there's a high likelihood a fast CME is headed towards Earth and we could see an impact on August 30.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
| C7.3/1F | 21:09 | S27E04 | 12860 | GOES16 | LDE |
August 25 and 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 fair.
The geomagnetic field is expected to be quiet to minor storm on August 28-30 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 | S25W31 | |||||||||
| S7041 | 2021.08.20 | N28W52 | |||||||||
| 12859 | 2021.08.20 2021.08.21 |
6 | 18 | 8 | N17W07 | 0050 | CSO | CAO |
 |
 |
location: N18W06 area: 0070 |
| S7044 | 2021.08.23 | N31W27 | |||||||||
| 12860 | 2021.08.24 2021.08.24 |
22 | 53 | 31 | S28E03 | 0330 | EKI | EAC |
 |
 |
location: S27E02 area: 0550 beta-gamma-delta |
| S7048 | 2021.08.24 | N23W07 | |||||||||
| 12861 | 2021.08.25 2021.08.26 |
1 | 3 | 1 | N15E38 | 0010 | AXX | BXO |
 |
 |
|
| S7050 | 2021.08.26 | 2 | N22E19 | 0003 | AXX |
 |
 |
||||
| 12862 | 2021.08.26 2021.08.27 |
4 | 7 | 4 | S28W67 | 0050 | BXO | DRO |
 |
 |
|
| S7052 | 2021.08.26 | 6 | 4 | S18E38 | 0012 | BXO |
 |
 |
|||
| Total spot count: | 33 | 89 | 48 | ||||||||
| Sunspot number: | 73 | 149 | 98 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 48 | 113 | 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): | 80 | 82 | 78 | ||||||||
| 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 | 76.2 (1) | 16.0 (2A) / 18.4 (2B) / 24.3 (2C) | (42.5 projected, +4.7) | (5.8) | |
| 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.
