The geomagnetic field was at quiet to unsettled levels on August 21. The high latitude magnetometer at Andenes recorded quiet to major storm levels. The above 10 MeV proton flux was at background levels at the end of the day.
Solar flux density measured at 20h UT on 2.8 GHz was 239.0 - increasing 64.2 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 170.76. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 170.76 on February 21, 2024). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.4). Three hour interval K indices: 31212211 (planetary), 12222422 (Boulder), 61224433 (Andenes).
The background x-ray flux is at the class C2 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 18 active regions using 2K resolution (SN: 402) and in 16 active regions using 1K resolution (SN: 265) SDO/HMI images.
AR 13788 [S08W73] was quiet and stable.
AR 13789 [N25W68] decayed slowly and quietly.
AR 13790 [S11W08] developed slowly and could produce a major flare.
AR 13792 [S17E08] was quiet and stable.
AR 13793 [N21W05] decayed slowly and was mostly quiet.
AR 13794 [N17W25] gained a few spots and was mostly quiet.
AR 13796 [S02E27] developed slowly and produced a major flare late in
the day.
AR 13797 [S04W55] decayed slowly and quietly.
AR 13798 [N06E48] was quiet and stable.
New AR 13799 [S10E62] rotated into view on August 20 and was numbered
by SWPC the next day. M flares are possible.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S10033 [S10E39] was quiet and stable.
S10038 [S28E43] developed slowly and was mostly quiet.
S10039 [N28E02] was quiet and stable.
New region S10041 [N27W12] emerged with tiny spots.
New region S10042 [N07E79] rotated into view with a few spots.
New region S10043 [N38E17] was observed with tiny spots in an
old plage area.
New region S10044 [N02E10] emerged with a tiny spot.
New region S10045 [N04E33] was observed with
tiny spots in an old plage area.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C4.6 | 00:25 | 13796 | |||
| C4.0 | 00:43 | 13789 | |||
| C5.3 | 01:01 | 13784 | |||
| C5.1 | 01:46 | 13789 | |||
| C5.8 | 02:08 | 13784 | |||
| C4.6 | 02:42 | northeast limb | S10042 | ||
| C3.3 | 03:39 | 13784 | |||
| C3.9 | 03:54 | 13790 | |||
| C4.5 | 04:15 | 13796 | |||
| C8.7 | 05:42 | 13796 | |||
| M1.1 | 06:02 | S02E41 | 13796 | ||
| C4.1 | 07:02 | 13784 | |||
| C4.1 | 07:11 | 13790 | |||
| C3.1 | 08:59 | 13784 | |||
| C4.7 | 09:51 | 13784 | |||
| C3.3 | 11:40 | 13790 | |||
| C3.3 | 12:02 | 13790 | |||
| C3.4 | 12:37 | 13793 | |||
| C3.8 | 14:24 | S10E72 | 13799 | ||
| C3.1 | 14:42 | S10038 | |||
| C3.2 | 15:26 | 13796 | |||
| C4.1 | 16:05 | 13784 | |||
| C8.8 | 16:32 | 13784 | LDE | ||
| C7.0 | 17:11 | 13794 | |||
| C4.8 | 18:53 | 13789 | |||
| C4.2 | 19:26 | 13799 | |||
| C3.7 | 20:28 | 13794 | |||
| C5.3 | 21:47 | 13796 | |||
| M5.1 | 22:08 | 13796 |
August 19-21: No obviously Earth directed CMEs were observed. Multiple farsided CMEs were observed on August 20.
[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 positive polarity northern hemisphere coronal hole (CH1236) was in an Earth facing position on August 18-19. Another positive polarity northern hemisphere coronal hole (CH1237) rotated across the central meridian on August 20.
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 at quiet to active levels on August 22 due to effects from CH1236 and on August 23 due to effects from CH1237. Quiet to unsettled is likely on August 24-25.
| Coronal holes (1) | Coronal mass ejections (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 colored red.
| 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 | ||||||||||
| 13785 | 2024.08.09 2024.08.11 |
2 | S12W89 | 0010 | BXO |
 |
rotated out of view |
||||
| 13788 | 2024.08.10 2024.08.11 |
1 | 1 | 1 | S08W75 | 0040 | HSX | HSX |
 |
 |
location: S08W73 area: 0090 |
| 13789 | 2024.08.10 2024.08.14 |
4 | 3 | 3 | N27W68 | 0060 | CAO | CRO |
 |
 |
location: N25W68 area: 0020 |
| 13791 | 2024.08.14 2024.08.16 |
S18W22 | location: S18W19 | ||||||||
| 13790 | 2024.08.15 2024.08.15 |
18 | 56 | 28 | S11W08 | 0500 | DKC | EKC |
 |
 |
beta-gamma-delta area: 0980 |
| S10022 | 2024.08.15 | S07W43 | |||||||||
| 13792 | 2024.08.16 2024.08.16 |
1 | 17 | 6 | S18E07 | 0400 | CKO | CHO |
 |
 |
beta-delta location: S17E08 area: 0570 |
| 13793 | 2024.08.16 2024.08.17 |
2 | 10 | 2 | N22W07 | 0010 | BXO | DRO |
 |
 |
location: N21W05 area: 0020 |
| S10025 | 2024.08.16 | N26W49 | |||||||||
| S10026 | 2024.08.16 | N15W48 | |||||||||
| 13794 | 2024.08.16 2024.08.17 |
5 | 27 | 13 | N18W25 | 0180 | DAI | DHI |
 |
 |
area: 0360 location: N17W25 |
| 13797 | 2024.08.17 2024.08.19 |
2 | 6 | 2 | S04W55 | 0010 | BXO | BXO |
 |
 |
|
| 13796 | 2024.08.17 2024.08.18 |
16 | 57 | 29 | S03E26 | 0350 | DKC | EKC |
 |
 |
beta-gamma-delta location: S02E41 area: 0650 |
| 13795 | 2024.08.17 2024.08.18 |
N02E25 | location: N02E30 | ||||||||
| S10031 | 2024.08.17 | N24E06 |
 |
||||||||
| S10032 | 2024.08.17 | S21W49 |
 |
||||||||
| S10033 | 2024.08.18 | 10 | 2 | S10E39 | 0015 | CRO |
 |
 |
|||
| S10034 | 2024.08.18 | N00W32 | |||||||||
| 13798 | 2024.08.19 2024.08.19 |
1 | 1 | 1 | N06E48 | 0060 | HSX | HSX |
 |
 |
area: 0130 |
| 13799 | 2024.08.20 2024.08.21 |
14 | 12 | 7 | S09E59 | 0110 | CSO | EKI |
 |
 |
area: 0500 location: S10E62 |
| S10038 | 2024.08.20 | 5 | 4 | S28E43 | 0060 | CAO |
 |
 |
|||
| S10039 | 2024.08.20 | 1 | 1 | N28E02 | 0003 | AXX |
 |
 |
|||
| S10040 | 2024.08.20 | N08W47 |
 |
||||||||
| S10041 | 2024.08.21 | 4 | 2 | N27W12 | 0015 | BXO |
 |
||||
| S10042 | 2024.08.21 | 4 | 2 | N07E79 | 0180 | HAX |
 |
||||
| S10043 | 2024.08.21 | 2 | N38E17 | 0002 | AXX |
 |
|||||
| S10044 | 2024.08.21 | 1 | N02E10 | 0001 | AXX |
 |
|||||
| S10045 | 2024.08.21 | 5 | 2 | N06E48 | 0010 | BXO |
 |
||||
| Total spot count: | 66 | 222 | 105 | ||||||||
| Sunspot number: | 176 | 402 | 265 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 121 | 301 | 184 | (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): | 194 | 221 | 212 | ||||||||
| 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 (SC24 solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (SC24 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 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.2 (+2.3) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.7 (+5.5) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 144.4 | 113.3 (+6.6) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 111.3 | 117.8 (+3.5) | 14.48 |
| 2023.03 | 157.2 | 155.6 | 123.3 | 121.1 (+3.3) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 97.6 | 122.9 (+1.8) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.4 | 124.2 (+1.3) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 160.5 | 125.3 (+1.1) | 8.95 |
| 2023.07 | 176.4 | 182.2 | 160.0 | 124.6 (-0.7) | 8.15 |
| 2023.08 | 153.7 | 157.6 | 114.8 | 124.3 (-0.3) | 7.19 |
| 2023.09 | 154.4 | 156.0 | 134.2 | 124.0 (-0.3) | 14.26 |
| 2023.10 | 142.8 | 141.9 | 99.4 | 124.8 (+0.8) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 105.4 | 127.8 (+3.0) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 114.2 | 129.4 (+1.6) | 9.60 |
| 2024.01 | 164.6 | 159.3 | 126.0 | 131.1 (+1.7) | 5.46 |
| 2024.02 | 172.5 | 168.3 | 123.0 | (137.4 projected, +6.3) | 5.31 |
| 2024.03 | 154.4 | 152.9 | 103.7 | (144.1 projected, +6.7) | 11.03 |
| 2024.04 | 161.3 | 162.6 | 136.5 | (148.2 projected, +4.1) | 9.69 |
| 2024.05 | 187.7 | 191.9 | 171.7 | (152.9 projected, +4.7) | 23.56 (SC25 peak) |
| 2024.06 | 184.3 | 190.2 | 164.2 | (156.9 projected, +4.0) | 10.24 |
| 2024.07 | 196.6 (cycle peak) |
203.0 | 196.5 (SC25 peak) | (158.7 projected, +1.8) | 7.13 |
| 2024.08 | 256.0 (1) | 147.7 (2A) / 218.0 (2B) / 224.8 (2C) | (159.1 projected, +0.4) | (17.7) | |
| 2024.09 | (161.0 projected, +1.9) | ||||
| 2024.10 | (162.8 projected, +1.8) | ||||
| 2024.11 | (160.8 projected, -2.0) | ||||
| 2024.12 | (156.4 projected, -4.4) | ||||
| 2025.01 | (150.3 projected, -6.1) | ||||
| 2025.02 | (143.0 projected, -7.3) | ||||
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: WDC-SILSO, Royal Observatory
Of Belgium, Brussels
Sunspot counts in July 2024 were the highest we've seen for a single month during solar cycle 25. The first part of August has seen very high sunspot counts, and there more than a remote possibility that we'll see activity in August approaching the most active months of solar cycle 23. With at least 4 consecutive months of high sunspot counts the projected peak for the smoothed ISN (365 days smoothing) has increased significantly to above 160. The month of the peak is currently likely to occur sometime between July and November 2024.
--------------------------------------------------------------------------------------
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.
