The geomagnetic field was quiet on August 25. Solar wind speed at SOHO ranged between 325 and 513 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels.
Solar flux density measured at 20h UT on 2.8 GHz was 138.9 - decreasing 39.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 153.16. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.6). Three hour interval K indices: 21001111 (planetary), 11111211 (Boulder), 32111223 (Andenes).
The background x-ray flux is at the class B4 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 160) and in 7 active regions using 1K resolution (SN: 96) SDO/HMI images.
Region 13405 [N09W73] produced a few C flares
and decayed slowly. C1 flares: C1.4 @ 03:29, C1.2 @ 09:17, C1.2 @ 11:17,
C1.3 @ 15:36 UT
Region 13411 [N14W54] was quiet and stable.
Region 13412 [N30W18] was quiet and stable.
Region 13413 [N09E17] developed early in the day gaining spots in the
north, then decayed slowly after noon.
Region 13414 [S15W11] was quiet and stable.
Region 13415 [S10E37] produced a minor M class flare and decayed
slowly.
New region 13416 [S19E69] rotated into view on August 24 and was
numbered the next day by SWPC. C1 flares: C1.1 @ 16:20 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8888 [N15E28] reemerged with a tiny spot.
S8889 [N23W06] reemerged with tiny spots.
New region S8895 [S17W54] emerged with a tiny spot.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| M1.4/1N | 01:09 | S12E50 | 13415 | GOES16 | |
| C5.0 | 15:49 | N09W70 | 13405 | GOES16 |
August 23-25: No obviously Earth directed CMEs were observed.
August 22: A faint CME was observed after a filament eruption in the
southwest quadrant early in the day. This CME could reach Earth on August 26.
[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 southern hemisphere coronal hole (CH1166) rotated across the central meridian 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 poor.
The geomagnetic field is expected to be quiet to unsettled on August 26-27 due to weak coronal hole effects and possibly some weak CME effects if the July 22 CME reaches Earth. On August 28-30 quiet conditions are likely.
| 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 | ||||||||||
| 13404 | 2023.08.13 2023.08.14 |
S09W85 |
location: S09W83 |
||||||||
| 13405 | 2023.08.13 2023.08.14 |
2 | 5 | 2 | N10W75 | 0120 | CAO | CKO |
 |
 |
area: 0270 location: N09W73 |
| 13411 | 2023.08.15 2023.08.17 |
1 | 3 | 2 | N14W56 | 0050 | HSX | CSO |
 |
 |
area: 0070 location: N14W54 |
| 13412 | 2023.08.17 2023.08.18 |
1 | 2 | 2 | N31W20 | 0060 | HSX | HSX |
 |
 |
area: 0090 location: N30W18 |
| 13414 | 2023.08.18 2023.08.21 |
16 | 4 | S10W23 | 0030 | BXO |
 |
 |
location: S15W11 | ||
| 13413 | 2023.08.20 2023.08.21 |
8 | 18 | 9 | N11E16 | 0400 | DKI | DKO |
 |
 |
area: 0580 location: N09E17 |
| S8883 | 2023.08.20 | N20W38 |
 |
||||||||
| 13415 | 2023.08.22 2023.08.22 |
4 | 11 | 6 | S09E35 | 0270 | DKO | DKC |
 |
 |
beta-delta location: S10E37 area: 0390 |
| S8888 | 2023.08.22 | 1 | N14E27 | 0002 | AXX |
 |
|||||
| S8889 | 2023.08.22 | 2 | N23W06 | 0003 | BXO |
 |
|||||
| S8890 | 2023.08.23 | S03W02 | |||||||||
| 13416 | 2023.08.24 2023.08.25 |
1 | 1 | 1 | S19E71 | 0030 | HSX | HSX |
 |
 |
area: 0090 location: S19E69 |
| S8893 | 2023.08.24 | S22E56 |
 |
||||||||
| S8894 | 2023.08.24 | N20E37 |
 |
||||||||
| S8895 | 2023.08.25 | 1 | S17W54 | 0001 | AXX |
 |
|||||
| Total spot count: | 17 | 60 | 26 | ||||||||
| Sunspot number: | 77 | 160 | 96 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 57 | 105 | 71 | (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): | 85 | 88 | 77 | ||||||||
| 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 |
| 2022.01 | 103.8 | 100.5 | 55.3 | 60.1 (+4.2) | 8.92 |
| 2022.02 | 109.1 | 106.5 | 60.9 | 64.7 (+4.6) | 10.46 |
| 2022.03 | 117.0 | 115.8 | 78.6 | 68.7 (+4.0) | 10.20 |
| 2022.04 | 130.8 | 131.7 | 84.0 | 73.0 (+4.3) | 11.79 |
| 2022.05 | 133.8 | 136.8 | 96.5 | 77.4 (+4.4) | 7.48 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 81.1 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.7 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.5 (+5.8) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.4 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.7 (+2.3) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.0 (+2.3) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.6 (+5.6) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | 113.3 (+6.7) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (119.1 projected, +5.8) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (124.4 projected, +5.3) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 96.4 | (130.5 projected, +6.1) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.9 | (136.1 projected, +5.6) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 163.4 | (139.3 projected, +3.2) | 8.95 |
| 2023.07 | 176.4 | 182.2 | 159.1 | (139.7 projected, +0.4) | 8.15 |
| 2023.08 | 156.9 (1) | 84.4 (2A) / 104.7 (2B) / 130.6 (2C) | (141.5 projected, +1.8) | (7.6) | |
| 2023.09 | (145.0 projected, +3.5) | ||||
| 2023.10 | (146.8 projected, +1.8) | ||||
| 2023.11 | (149.4 projected max SC25, +2.6) | ||||
| 2023.12 | (148.6 projected, -0.8) | ||||
| 2024.01 | (145.7 projected, -2.9) | ||||
| 2024.02 | (144.3 projected, -1.4) | ||||
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
Looking back 6 months, the 365d smoothed values for solar flux and all sunspot numbers with the exception of NOAA's, are all above their solar cycle 24 peak. The first peak of solar cycle 25 is projected to be between July 7 and 10, 2023 (solar flux on July 7, ISN and STAR 1K and 2K all have that peak on July 9, while NOAA peaks on July 10). This is unlikely to be the final peak of SC25, there is only a small chance that it is the actual sunspot and solar flux maximum.
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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.
