The geomagnetic field was quiet on August 24. The high latitude magnetometer at Andenes recorded quiet to unsettled conditions. Solar wind speed and density increased slowly after noon due to CH1026, however, the field didn't become unsettled until early on August 25.
Solar flux density measured at 20h UT on 2.8 GHz was 80.9 - increasing 2.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 77.81). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.4). Three hour interval K indices: 10111122 (planetary), 10122322 (Boulder), 00111132 (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 6 active regions using 2K resolution (SN: 98) and in 3 active region using 1K resolution (SN: 48) SDO/HMI images.
Region 12859 [N18E33] decayed slowly. The region has weak polarity intermixing.
The region produced a C1.5 flare at 14:49 UT. A B8.8 flare peaking at 12:16
triggered a filament eruption, which was associated with an EIT wave and a
CME.
New region 12860 [S28E42] emerged with many spots. C flares are
possible.
Spotted regions not observed (or interpreted
differently) by SWPC:
S7040 [S25E08] reemerged with tiny spots.
S7041 [N28E13] reemerged with a tiny spot.
New region S7047 [N33W47] emerged with a tiny spot.
New region S7048 [N23E32] emerged to the north
of AR 12859 with a tiny spot.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
August 22: No obviously Earth directed CMEs
were observed in available LASCO imagery.
August 23: A slow moving faint full halo CME was observed in LASCO C3
imagery after 07h UT. The CME was associated with a filament eruption in the
northern hemisphere close to the central meridian.
August 24: A slow moving CME was observed mainly over the east limb
following a filament eruption just after noon. Some material was observed
off the west limb as well, however, it is uncertain if this was associated
with the same event.
[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 extension (CH1026) of the northern polar coronal hole rotated across the central meridian on August 20-21. A small northern hemisphere coronal hole (CH1027) was Earth facing on August 23.
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 fair.
The geomagnetic field is expected to be quiet to active on August 25 due to effects from CH1026. A disturbance related to CH1027 could start on August 26, however, this may be preceded by the arrival of the August 23 CME. Quiet to active conditions are likely on August 26-27, with a chance of minor storm intervals. There is a slight chance the August 24 CME could have an Earth directed component, if so that disturbance could arrive late on August 27 or on August 28.
| 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 | ||||||||||
| 12858 | 2021.08.17 2021.08.18 |
N13W84 |
location N13W79 |
||||||||
| S7040 | 2021.08.18 | 3 | S25E08 | 0006 | AXX |
 |
|||||
| S7041 | 2021.08.20 | 1 | N28W13 | 0001 | AXX |
 |
|||||
| 12859 | 2021.08.20 2021.08.21 |
4 | 14 | 7 | N19E32 | 0150 | HSX | CSO |
 |
 |
area: 0090 location: N18E34 |
| S7044 | 2021.08.23 | N31E12 |
 |
||||||||
| 12860 | 2021.08.24 2021.08.24 |
5 | 18 | 10 | S28E41 | 0110 | BXO | DRI |
 |
||
| S7047 | 2021.08.24 | 1 | N33W47 | 0001 | AXX |
 |
|||||
| S7048 | 2021.08.24 | 1 | 1 | N23E32 | 0002 | AXX |
 |
||||
| Total spot count: | 9 | 38 | 18 | ||||||||
| Sunspot number: | 29 | 98 | 48 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 14 | 46 | 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): | 32 | 54 | 38 | ||||||||
| 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 | 74.8 (1) | 11.2 (2A) / 14.5 (2B) / 20.6 (2C) | (42.5 projected, +4.7) | (5.2) | |
| 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.
