The geomagnetic field was at quiet to minor storm levels on August 31 due to CME effects. Solar wind speed at SOHO ranged between 349 and 449 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor 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 231.6 - decreasing 13.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 173.12. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 173.12 on March 2, 2024). The Potsdam WDC planetary A index was 24 (STAR Ap - based on the mean of three hour interval ap indices: 24.5). Three hour interval K indices: 44523543 (planetary), 43614543 (Boulder), 45425554 (Andenes).
The background x-ray flux is at the class C4 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 18 active regions using 2K resolution (SN: 377) and in 15 active regions using 1K resolution (SN: 249) SDO/HMI images.
AR 13799 [S11W72] was mostly quiet and stable.
AR 13800 [S28W78] rotated mostly out of view with only small trailing
spots visible at the end of the day.
AR 13801 [N08W54] decayed slowly and quietly.
AR 13803 [N14E03] decayed slowly and quietly.
AR 13804 [S24W01] decayed slowly and quietly.
AR 13805 [N09W07] was quiet and stable.
AR 13806 [S11E29] decayed slightly, however, further M class flaring
is likely.
AR 13807 [S16W18] extended longitudinally and produced a few C
flares.
AR 13808 [S10E42] decayed slowly and gained a weak magnetic delta in
the leading penumbra.
New AR 13809 [S21E38] emerged on August 30 and was numbered by SWPC
the next day as slow development continued.
New AR 13810 [N16E35] emerged with several spots.
New AR 13811 [S09E73] rotated into view with a large, mature spot.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S10066 [N25E19] was quiet and stable.
S10072 [S06E12] decayed slowly and quietly.
S10073 [N15E57] reemerged with tiny spots.
S10075 [S21W07] developed before noon, then
decayed slowly.
S10076 [S08E63] gained more tiny spots.
New region S10081 [S19E58] emerged with a tiny spot.
An active region (AR S10082) is rotating into view at the southeast limb early on September 1. This region is unstable and could produce M flares.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C4.7 | 00:10 | 13811 | GOES16 | ||
| C5.3 | 00:15 | 13807 | GOES16 | ||
| M1.1 | 00:49 | S11E47 | 13806 | GOES16 | simultaneous flare in AR 13807 |
| M1.2 | 02:38 | S08E45 | 13806 | GOES16 | |
| C4.6 | 04:03 | S10082 | GOES16 | ||
| C4.3 | 04:46 | 13807 | GOES16 | ||
| C4.2 | 06:55 | S10082 | GOES16 | ||
| C9.3 | 08:24 | 13811 | GOES16 | ||
| M1.2 | 08:59 | S10082 | GOES16 | ||
| C4.2 | 10:27 | 13807 | GOES16 | ||
| C9.0 | 11:43 | 13806 | GOES16 | ||
| C6.1 | 12:48 | 13807 | GOES16 | ||
| M1.8 | 13:02 | 13806 | GOES16 | ||
| C4.3 | 14:51 | 13799 | GOES16 | ||
| C4.6 | 14:56 | S10082 | GOES16 | ||
| C3.4 | 15:46 | 13799 | GOES16 | ||
| C7.3 | 17:51 | S10082 | GOES16 | SWPC incorrectly attributes this to AR 13799 | |
| C5.7 | 18:35 | 13807 | GOES16 | ||
| C6.5 | 18:48 | 13808 | GOES16 | ||
| C6.5 | 19:16 | 13807 | GOES16 | ||
| C8.4 | 20:18 | 13806 | GOES16 | simultaneous, similar magnitude flare in AR 13800 | |
| C6.7 | 20:40 | 13806 | GOES16 | simultaneous flare in AR 13800 | |
| C7.7 | 20:49 | S10082 | GOES16 | ||
| C6.8 | 21:02 | 13799 | GOES16 | ||
| C5.2 | 21:56 | 13807 | GOES16 | ||
| C9.7 | 23:39 | 13806 | GOES16 | ||
| C7.4 | 23:59 | 13807 | GOES16 |
August 29-31: No obviously Earth directed CMEs were observed.
[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 narrow trans equatorial negative polarity coronal hole (CH1239) was in an Earth facing position on August 29-30. A positive polarity northern hemisphere coronal hole (CH1240) could rotate into an Earth facing position on September 3.
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 September 1 due to CME effects and quiet to unsettled on September 2-3 due to weak effects from CH1239.
| 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 | ||||||||||
| 13798 | 2024.08.19 2024.08.19 |
N06W87 |
 |
location: N07W85 |
|||||||
| 13799 | 2024.08.20 2024.08.21 |
5 | 5 | 4 | S11W73 | 0280 | CKO | CHO |
 |
 |
area: 0430 location: S11W72 |
| 13800 | 2024.08.20 2024.08.22 |
3 | 3 | 2 | S28W88 | 0220 | ESO | HRX |
 |
 |
location: S28W78 area: 0030 |
| 13801 | 2024.08.21 2024.08.22 |
4 | 6 | 3 | N08W55 | 0040 | CAO | CSO |
 |
 |
area: 0050 location: N08W54 |
| S10047 | 2024.08.22 | N21W56 | |||||||||
| 13803 | 2024.08.25 2024.08.26 |
5 | 13 | 5 | N14E06 | 0040 | CAO | CRO |
 |
 |
location: N14E03 area: 0025 |
| 13804 | 2024.08.25 2024.08.26 |
1 | 10 | 2 | S24W02 | 0050 | HSX | CRO |
 |
 |
location: S24W01 area: 0040 |
| 13805 | 2024.08.26 | 4 | 3 | N08W07 | 0008 | BXO |
 |
 |
location: N09W07 | ||
| S10060 | 2024.08.26 | S07E15 | |||||||||
| 13807 | 2024.08.27 2024.08.30 |
20 | 27 | 17 | S16W18 | 0320 | EKI | ESI |
 |
 |
beta-gamma area: 0480 |
| 13806 | 2024.08.27 2024.08.28 |
25 | 66 | 35 | S11E34 | 0480 | FKC | EKC |
 |
 |
beta-gamma location: S11E29 area: 0590 |
| S10063 | 2024.08.27 | N09W28 | |||||||||
| S10064 | 2024.08.27 | S08W05 | |||||||||
| S10065 | 2024.08.28 | N21E11 | |||||||||
| S10066 | 2024.08.28 | 4 | N23E19 | 0004 | BXO |
 |
 |
||||
| S10067 | 2024.08.28 | N25W39 |
 |
||||||||
| S10068 | 2024.08.28 | N01W01 | |||||||||
| S10069 | 2024.08.28 | S16W32 | |||||||||
| 13808 | 2024.08.29 2024.08.30 |
2 | 8 | 6 | S09E44 | 0060 | CAO | DAO |
 |
 |
beta-delta location: S10E42 area: 0100 |
| S10071 | 2024.08.29 | N17E17 | |||||||||
| S10072 | 2024.08.29 | 12 | 2 | S06E12 | 0020 | BXO |
 |
 |
|||
| S10073 | 2024.08.29 | 2 | N15E57 | 0003 | BXO |
 |
|||||
| S10074 | 2024.08.29 | S05W35 | |||||||||
| S10075 | 2024.08.30 | 11 | 5 | S21W07 | 0030 | DRO |
 |
 |
|||
| S10076 | 2024.08.30 | 9 | 5 | S08E63 | 0025 | BXO |
 |
 |
|||
| S10077 | 2024.08.30 | S14W25 |
 |
||||||||
| 13809 | 2024.08.30 | 1 | 6 | 4 | S20E39 | 0020 | HSX | DRO |
 |
 |
location: S21E38 |
| 13810 | 2024.08.31 2024.08.31 |
3 | 9 | 5 | N16E35 | 0010 | BXO | DRO |
 |
was AR S10079 area: 0040 |
|
| 13811 | 2024.08.31 2024.08.31 |
1 | 1 | 1 | S09E73 | 0120 | HSX | HHX |
 |
was AR S10080 area: 0330 |
|
| S10081 | 2024.08.31 | 1 | S19E58 | 0001 | AXX |
 |
|||||
| Total spot count: | 70 | 197 | 99 | ||||||||
| Sunspot number: | 180 | 377 | 249 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 135 | 260 | 162 | (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): | 198 | 207 | 199 | ||||||||
| 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 | 136.8 (+5.7) | 5.31 |
| 2024.03 | 154.4 | 152.9 | 103.7 | (143.3 projected, +6.5) | 11.03 |
| 2024.04 | 161.3 | 162.6 | 136.5 | (147.8 projected, +4.5) | 9.69 |
| 2024.05 | 187.7 | 191.9 | 171.7 | (152.6 projected, +4.8) | 23.56 (SC25 peak) |
| 2024.06 | 184.3 | 190.2 | 164.2 | (156.5 projected, +4.0) | 10.24 |
| 2024.07 | 196.6 |
203.0 | 196.5 | (158.3 projected, +1.8) | 7.13 |
| 2024.08 | 246.1 (cycle peak) |
252.2 | 215.5 (SC25 peak) | (158.7 projected, +0.4) | 15.5 |
| 2024.09 | (1) | (2A / 2B) / 219.9 (2C) | (160.8 projected, +2.1) | () | |
| 2024.10 | (162.7 projected, +1.9) | ||||
| 2024.11 | (160.7 projected, -2.0) | ||||
| 2024.12 | (156.4 projected, -4.3) | ||||
| 2025.01 | (150.3 projected, -6.1) | ||||
| 2025.02 | (143.0 projected, -7.3) | ||||
| 2025.03 | (136.2 projected, -6.8) | ||||
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.
