The geomagnetic field was at quiet to active levels on September 1 due to CME effects most of the day. Late in the day a stream from CH1239 became the dominant solar wind source. Solar wind speed at SOHO ranged between 374 and 452 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at 0.7 pfu at the end of the day and is increasing slowly early on September 2.
Solar flux density measured at 20h UT on 2.8 GHz was 225.5 - decreasing 21.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 173.38. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 173.38 on March 3, 2024). The Potsdam WDC planetary A index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 14.0). Three hour interval K indices: 43223422 (planetary), 33344*** (Boulder), 44225533 (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: 395) and in 16 active regions using 1K resolution (SN: 258) SDO/HMI images.
AR 13801 [N08W68] decayed slowly and quietly.
AR 13803 [N14E03] decayed slowly and quietly.
AR 13804 [S24W14] decayed slowly and quietly.
AR 13805 [N08W22] was quiet and stable.
AR 13806 [S11E17] decayed further losing area and complexity. Flare
activity was much reduced compared to the previous days.
AR 13807 [S17W31] developed slowly gaining area and spots. M flares
are possible.
AR 13808 [S10E28] decayed further and was quiet.
AR 13809 [S20E25] decayed slowly and quietly.
AR 13810 [N16E22] decayed slowly and quietly.
AR 13811 [S10E60] was quiet and stable.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S10066 [N24E07] was quiet and stable.
S10072 [S08E00] was quiet and stable.
S10073 [N14E43] was quiet and stable.
S10075 [S22W21] decayed slowly and quietly.
S10076 [S08E49] was quiet and stable.
New region S10082 [S21E75] began to rotate into view early in the day
and was by a large margin the most active spot group on the visible disk.
Major flaring is likely, and another proton flare is possible.
New region S10083 [N07E09] was observed with tiny spots in an old
plage area.
New region S10084 [N17E62] was observed with a tiny spot in an
old plage area.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C4.7 | 01:21 | S10082 | GOES16 | ||
| C4.8 | 02:01 | S10082 | GOES16 | ||
| C6.8 | 02:25 | S09W77 | 13799 | GOES16 | |
| C4.5 | 02:44 | S10082 | GOES16 | ||
| C9.4 | 03:33 | S12E31 | 13806 | GOES16 | |
| C6.0 | 05:34 | S10082 | GOES16 | ||
| C7.5 | 06:43 | S10082 | GOES16 | ||
| C6.7 | 07:21 | S10082 | GOES16 | ||
| M1.4 | 07:57 | S10082 | GOES16 | ||
| C4.7 | 09:13 | S10082 | GOES16 | ||
| C3.7 | 10:11 | 13811 | GOES16 | ||
| C4.7 | 10:59 | S10082 | GOES16 | ||
| C8.1 | 11:23 | S10082 | GOES16 | ||
| M5.5 | 13:21 | S10082 | GOES16 | LDE, very impressive full halo CME, proton event | |
| M1.9 | 16:20 | 13806 | GOES16 | ||
| M1.1 | 18:03 | 13807 | GOES16 | ||
| M1.1 | 20:00 | S10082 | GOES16 | ||
| M1.0 | 20:20 | S10082 | GOES16 | ||
| M1.5 | 22:48 | 13807 | GOES16 |
August 30-31: No obviously Earth directed CMEs were observed.
September 1: A full halo CME was observed after the long duration
M5.5 flare in AR S10082. While the main part of the CME won't affect Earth,
there is a small chance of a solar wind shock and a minor disturbance on
September 4.
[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 unsettled on September 2-3 due to weak effects from CH1239. Mostly quiet conditions are likely on September 4, however, there is a chance of effects from the September 1 CME and quiet to active disturbance levels.
| 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 | ||||||||||
| 13799 | 2024.08.20 2024.08.21 |
1 | S11W86 | 0220 | HSX |
 |
rotated out of view | ||||
| 13801 | 2024.08.21 2024.08.22 |
2 | 4 | 3 | N08W68 | 0030 | BXO | HRX |
 |
 |
area: 0025 |
| 13803 | 2024.08.25 2024.08.26 |
4 | 14 | 3 | N14W08 | 0020 | BXO | CRO |
 |
 |
location: N14W09 area: 0025 |
| 13804 | 2024.08.25 2024.08.26 |
1 | 6 | 3 | S24W14 | 0020 | HSX | BXO |
 |
 |
|
| 13805 | 2024.08.26 | 4 | 2 | N08W21 | 0009 | BXO |
 |
 |
location: N08W22 | ||
| S10060 | 2024.08.26 | S07E02 | |||||||||
| 13807 | 2024.08.27 2024.08.30 |
15 | 47 | 23 | S16W31 | 0550 | EKI | EKI |
 |
 |
beta-gamma area: 0810 |
| 13806 | 2024.08.27 2024.08.28 |
22 | 62 | 33 | S11E20 | 0380 | EKC | EKC |
 |
 |
beta-gamma-delta location: S11E17 area: 0490 |
| S10063 | 2024.08.27 | N09W41 | |||||||||
| S10064 | 2024.08.27 | S08W18 | |||||||||
| S10065 | 2024.08.28 | N21W02 | |||||||||
| S10066 | 2024.08.28 | 4 | 1 | N24E07 | 0007 | BXO |
 |
 |
|||
| S10067 | 2024.08.28 | N25W52 | |||||||||
| S10068 | 2024.08.28 | N01W14 | |||||||||
| S10069 | 2024.08.28 | S16W45 | |||||||||
| 13808 | 2024.08.29 2024.08.30 |
3 | 8 | 5 | S10E31 | 0090 | CAO | DAO |
 |
 |
location: S10E28 |
| S10071 | 2024.08.29 | N17E04 | |||||||||
| S10072 | 2024.08.29 | 15 | 2 | S08E00 | 0030 | BXO |
 |
 |
|||
| S10073 | 2024.08.29 | 5 | 2 | N14E43 | 0015 | CRO |
 |
 |
|||
| S10074 | 2024.08.29 | S05W48 | |||||||||
| S10075 | 2024.08.30 | 7 | 2 | S22W21 | 0015 | BXO |
 |
 |
|||
| S10076 | 2024.08.30 | 9 | 5 | S08E49 | 0025 | BXO |
 |
 |
|||
| S10077 | 2024.08.30 | S14W38 | |||||||||
| 13809 | 2024.08.30 | 1 | 4 | S21E26 | 0010 | AXX | BXO |
 |
 |
location: S20E25 | |
| 13810 | 2024.08.31 2024.08.31 |
3 | 7 | 4 | N16E24 | 0020 | BXO | DRO |
 |
 |
area: 0030 location: N16E22 |
| 13811 | 2024.08.31 2024.08.31 |
4 | 2 | 1 | S10E56 | 0220 | CSO | HHX |
 |
 |
area: 0360 |
| S10081 | 2024.08.31 | S19E45 |
 |
||||||||
| S10082 | 2024.09.01 | 12 | 7 | S21E75 | 0600 | EAC |
 |
||||
| S10083 | 2024.09.01 | 4 | 2 | N07E09 | 0010 | AXX |
 |
||||
| S10084 | 2024.09.01 | 1 | N17E62 | 0002 | AXX |
 |
|||||
| Total spot count: | 56 | 215 | 98 | ||||||||
| Sunspot number: | 156 | 395 | 258 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 96 | 267 | 150 | (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): | 171 | 217 | 206 | ||||||||
| 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) | 15.8 |
| 2024.09 | 225.5 (1) | 5.2 (2A) / 156 (2B) / 217.3 (2C) | (160.8 projected, +2.1) | (14.0) | |
| 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.
