The geomagnetic field was quiet to unsettled on August 18 under the influence of effects from CH1165. Solar wind speed at SOHO ranged between 326 and 569 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.
Solar flux density measured at 20h UT on 2.8 GHz was 150.6 - decreasing 23.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 152.33. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.3). Three hour interval K indices: 22331233 (planetary), 23332323 (Boulder), 23331335 (Andenes).
The background x-ray flux is at the class B7 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 261) and in 12 active regions using 1K resolution (SN: 170) SDO/HMI images.
Region 13403 [N26W37] decayed in the trailing
spots section and was mostly quiet. C1 flares: C1.0 @ 09:23 UT
Region 13404 [S09E08] decayed slowly and quietly.
Region 13405 [N10E20] decayed in the trailing spot section and was
mostly quiet.
Region 13406 [S16W62] decayed early in the day, then developed slowly
after noon.
Region 13407 [S19W17] decayed slowly and quietly.
Region 13409 [N20W41] decayed early in the day, some development was
observed after noon. C1 flares: C1.7 @ 10:48 UT
Region 13411 [N13E37] gained spots and was quiet.
New region 13412 [N31E71] rotated into view on August 17 with SWPC
numbering the region the next day.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8850 [N23W18] was quiet and stable.
S8875 [S18E07] was quiet and stable.
New region S8876 [S11E73] rotated into view before noon with small
spots.
New region S8877 [N27E30] emerged with tiny spots.
New region S8878 [N15W48] emerged with tiny spots.
New region S8879 [N32E04] was observed with tiny spots in an
old plage area.
New region S8880 [S01E34] emerged with a tiny spot.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.1 | 02:52 | N11E50 | 13405 | GOES16 | simultaneous flare in AR S8850 |
| C3.7 | 19:30 | N19W43 | 13409 | GOES16 | |
| C3.0 | 21:35 | 13409 | GOES16 |
August 16-18: 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 southern hemisphere coronal hole (CH1165) rotated across the central meridian on August 13-14.
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.
The geomagnetic field is expected to be quiet on August 18-20.
| 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 | ||||||||||
| S8839 | 2023.08.08 | S28W50 | |||||||||
| S8848 | 2023.08.10 | N22W50 |
 |
||||||||
| S8850 | 2023.08.11 | 10 | N23W18 | 0020 | BXO |
 |
 |
||||
| S8851 | 2023.08.11 | N10W47 | |||||||||
| 13403 | 2023.08.13 2023.08.13 |
12 | 25 | 13 | N26W35 | 0160 | DAI | EAI |
 |
 |
area: 0240 location: N26W37 |
| 13406 | 2023.08.13 2023.08.15 |
4 | 2 | S17W62 | 0020 | CRO |
 |
 |
|||
| 13404 | 2023.08.13 2023.08.14 |
1 | 6 | 3 | S10E07 | 0010 | HAX | CAO |
 |
 |
area: 0040 location: S09E08 |
| 13409 | 2023.08.13 2023.08.16 |
5 | 14 | 8 | N20W42 | 0020 | BXO | DRI |
 |
 |
beta-gamma area: 0060 location: N20W41 |
| 13405 | 2023.08.13 2023.08.14 |
6 | 12 | 7 | N11E25 | 0140 | ESO | ESO |
 |
 |
area: 0200 location: N10E20 |
| 13407 | 2023.08.14 2023.08.15 |
5 | 9 | 4 | S18W13 | 0140 | DSO | DSO |
 |
 |
area: 0290 location: S18W17 |
| S8861 | 2023.08.14 | S06E02 | |||||||||
| S8864 | 2023.08.14 | N19W17 | |||||||||
| S8865 | 2023.08.14 | S09W34 | |||||||||
| S8866 | 2023.08.14 | S33W16 | |||||||||
| 13411 | 2023.08.15 2023.08.17 |
1 | 9 | 6 | N15E35 | 0030 | HSX | CSO |
 |
 |
location: N13E37 area: 0120 |
| 13408 | 2023.08.15 2023.08.16 |
S18W32 |
 |
location: S19W31 |
|||||||
| 13410 | 2023.08.16 | 1 | S30W62 | 0010 | AXX | for the third consecutive day SWPC reports a spot at a location where there are no spots | |||||
| S8869 | 2023.08.16 | N12W02 |
 |
||||||||
| S8870 | 2023.08.16 | N14W09 | |||||||||
| S8872 | 2023.08.16 | S25W15 |
 |
||||||||
| S8873 | 2023.08.16 | N15E06 | |||||||||
| 13412 | 2023.08.17 2023.08.18 |
1 | 1 | 1 | N32E72 | 0060 | HSX | HSX |
 |
 |
area: 0110 location: N31E71 |
| S8875 | 2023.08.17 | 4 | 1 | S18E07 | 0010 | BXO |
 |
 |
|||
| S8876 | 2023.08.18 | 3 | 2 | S11E73 | 0030 | CRO |
 |
||||
| S8877 | 2023.08.18 | 6 | 2 | N27E30 | 0015 | CRO |
 |
||||
| S8878 | 2023.08.18 | 2 | 1 | N15W48 | 0004 | BXO |
 |
||||
| S8879 | 2023.08.18 | 5 | N32E04 | 0008 | AXX |
 |
|||||
| S8880 | 2023.08.18 | 1 | S01E34 | 0001 | AXX |
 |
|||||
| Total spot count: | 32 | 111 | 50 | ||||||||
| Sunspot number: | 112 | 261 | 170 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 78 | 153 | 92 | (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): | 123 | 144 | 136 | ||||||||
| 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 | 160.9 (1) | 63.3 (2A) / 109.0(2B) / 139.3 (2C) | (141.5 projected, +1.8) | (8.3) | |
| 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
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.
