The geomagnetic field was at active to minor storm levels on March 13, strongly under the influence of effects associated with CH1275. Solar wind speed at SOHO ranged between 498 and 623 km/sec, averaging 540 km/sec (+28 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded unsettled to major storm levels. The above 10 MeV proton flux was at background levels.
Solar flux density measured at 20h UT on 2.8 GHz was 175.9 - decreasing 8.1 over the previous solar rotation. The SF measurement at 20h may have been slightly flare enhanced. (Centered 1 year average SF at 1 AU - 183 days ago: 194.23. In comparison SC24 peaked on June 28, 2014 at 145.50 while SC23 peaked on February 23, 2002 at 198.15. Current SC25 peak: 194.23 on September 12, 2024 (subtracting a baseline solar flux level of 65, this is +60.53% compared to the SC24 peak and -2.95% compared to the SC23 peak). The Potsdam WDC planetary A index was 36 (STAR Ap - based on the mean of three hour interval ap indices: 35.9). Three hour interval K indices: 55445454 (planetary), 45545554 (Boulder), 56445366 (Andenes).
The background x-ray flux is at the class C1 level (GOES 18).
At the time of counting spots (see image time), spots were observed in 20 active regions using 2K resolution (SN: 406) and in 16 active regions using 1K resolution (SN: 260) SDO/HMI images.
AR 14018 [S20W25] was mostly quiet and stable.
C1 flares: C1.9 @ 02:05 UT
AR 14019 [N05W08] has multiple magnetic delta configurations and
could produce an M flare. C1 flares: C1.4 @ 04:16, C1.7 @ 09:04, C1.8 @
10:40, C1.5 @ 12:59 UT
AR 14020 [N19E12] was quiet and stable.
AR 14021 [S05E30] was mostly quiet as the magnetic delta diminished.
AR 14022 [N07E18] gained spots and was mostly quiet.
AR 14023 [N25E33] was quiet and stable.
AR 14024 [N05W81] gained tiny spots and appears to be developing.
AR 14025 [N11E31] developed slowly and quietly.
AR 14026 [S20E38] decayed slowly and quietly.
AR 14027 [N11W36] was mostly quiet and stable. C1 flares: C1.5 @
01:28 UT
AR 14028 [S17E67] rotated fully into view and produced low
level C flares. C1 flares: C1.5 @ 03:34, C1.3 @ 05:02, C1.8 @ 04:35, C1.6 @
05:26, C1.5 @ 10:10, C1.9 @ 10:17, C1.9 @ 15:01 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S10880 [N16E42] reemerged with tiny spots.
S10883 [S11E16] developed further and was quiet.
S10887 [S06W15] was quiet and stable.
New region S10889 [N06E21] emerged before noon with a few spots, then
decayed slowly.
New region S10890 [N04E39] emerged with a tiny
spot.
New region S10891 [S17W33] emerged with tiny spots.
New region S10892 [N17W48] emerged with tiny spots.
New region S10893 [N08E59] was observed with a tiny spot in an old
plage area.
New region S10894 [S16E79] rotated into view
with mature spots.
AR 14012 at the southwest limb produced a C1.6 flare at 02:52 UT
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.1 | 05:08 | 14028 | GOES18 | ||
| C6.8 | 07:52 | 14012 | GOES16 | ||
| C3.9 | 08:14 | 14018 | GOES16 | ||
| C2.9 | 14:47 | 14019 | GOES16 | ||
| C4.3 | 17:42 | 14028 | GOES16 | ||
| C3.7 | 18:13 | behind northeast limb | GOES16 | ||
| C3.5 | 19:05 | GOES16 | |||
| C7.8/1F | 19:29 | N04W06 | 14019 | GOES16 | |
| C7.9 | 19:35 | 14028 | GOES16 | ||
| C2.1 | 22:21 | 14024 | GOES16 | ||
| C2.0 | 22:38 | 14019 | GOES16 |
March 11-13: No obviously Earth directed CMEs.
[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 recurrent southern hemisphere negative polarity coronal hole (CH1275) rotated across the central meridian on March 9-10. A southern hemisphere negative polarity coronal hole (CH1276) was Earth facing on March 13.
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 fair.
The geomagnetic field is expected to be at quiet to major storm levels on March 14 due to effects from CH1275 and mostly quiet on March 15-16. March 17 could see some unsettled and active intervals due to effects associated with CH1276.
| 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 |
STAR | SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 14016 | 2025.03.03 2025.03.04 |
S25W74 |
was AR S10858 location: S26W69 |
||||||||
| 14017 | 2025.03.04 2025.03.05 |
S05W58 |
was AR S10860 location: S04W47 |
||||||||
| S10863 | 2025.03.04 | N11W53 | |||||||||
| 14018 | 2025.03.05 2025.03.05 |
3 | 9 | 5 | S21W24 | 0100 | HSX | CSO |
 |
 |
area: 0180 location: S20W25 |
| 14019 | 2025.03.06 2025.03.07 |
16 | 42 | 27 | N06W09 | 0200 | DAC | DAC |
 |
 |
beta-gamma-delta was AR S10866 area: 0310 location: N05W08 |
| 14020 | 2025.03.08 2025.03.09 |
1 | 4 | 2 | N19E11 | 0050 | HSX | CSO |
 |
 |
was AR S10870 location: N19E12 area: 0100 |
| 14027 | 2025.03.08 2025.03.12 |
1 | 2 | 1 | N11W36 | 0010 | AXX | CRO |
 |
 |
was AR S10871 area: 0020 |
| S10873 | 2025.03.08 | S10W40 |
 |
||||||||
| 14021 | 2025.03.09 2025.03.10 |
7 | 17 | 6 | S06E29 | 0100 | CAI | DKC |
 |
 |
beta-delta was AR S10876 area: 0260 location: S05E30 |
| S10877 | 2025.03.09 | S13W36 | |||||||||
| 14024 | 2025.03.10 2025.03.11 |
1 | 6 | 2 | N05W83 | 0010 | AXX | BXO |
 |
 |
was AR S10878 location: N05W81 |
| 14023 | 2025.03.10 2025.03.11 |
1 | 5 | 2 | N25E32 | 0030 | HSX | HAX |
 |
 |
was AR S10879 area: 0070 location: N25E33 |
| S10880 | 2025.03.10 | 7 | 2 | N16E42 | 0015 | BXO |
 |
||||
| 14022 | 2025.03.10 2025.03.11 |
6 | 26 | 13 | N08E19 | 0030 | DRO | CRI |
 |
 |
was AR S10881 area: 0070 location: N07E18 |
| 14026 | 2025.03.11 2025.03.12 |
3 | 9 | 5 | S20E37 | 0010 | BXO | CRI |
 |
 |
was AR S10882 location: S20E38 area: 0030 |
| S10883 | 2025.03.11 | 24 | 9 | S11E16 | 0050 | DRO |
 |
 |
|||
| 14025 | 2025.03.11 2025.03.12 |
7 | 20 | 12 | N10E28 | 0030 | DRO | DAO |
 |
 |
was AR S10884 location: N11E31 area: 0180 |
| S10886 | 2025.03.12 | N18W56 |
 |
||||||||
| S10887 | 2025.03.12 | 4 | S06W15 | 0006 | BXO |
 |
 |
||||
| S10888 | 2025.03.12 | S14E59 |
 |
||||||||
| 14028 | 2025.03.12 2025.03.12 |
4 | 22 | 12 | S17E65 | 0120 | DAI | DAI |
 |
 |
beta-gamma area: 0260 location: S17E67 |
| S10889 | 2025.03.13 | 3 | N06E21 | 0004 | AXX |
 |
|||||
| S10890 | 2025.03.13 | 1 | 1 | N04E39 | 0003 | AXX |
 |
||||
| S10891 | 2025.03.13 | 2 | 1 | S17W33 | 0005 | AXX |
 |
||||
| S10892 | 2025.03.13 | 2 | N17E48 | 0003 | BXO |
 |
|||||
| S10893 | 2025.03.13 | 1 | N08E59 | 0001 | AXX |
 |
|||||
| S10894 | 2025.03.13 | 2 | 2 | S16E79 | 0170 | HSX |
 |
||||
| Total spot count: | 50 | 206 | 100 | ||||||||
| Sunspot number: | 160 | 406 | 260 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 86 | 263 | 157 | (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): | 176 | 223 | 208 | ||||||||
| 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 |
| 2023.09 | 154.4 | 156.0 | 134.2 | 124.0 (-0.3) | 14.26 |
| 2023.10 | 142.8 | 141.9 | 99.9 | 124.8 (+0.8) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 107.1 | 127.9 (+3.1) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 113.5 | 129.5 (+1.6) | 9.60 |
| 2024.01 | 164.6 | 159.3 | 126.0 | 131.2 (+1.7) | 5.46 |
| 2024.02 | 172.5 | 168.3 | 123.0 | 136.9 (+5.7) | 5.31 |
| 2024.03 | 154.4 | 152.9 | 103.7 | 141.4 (+4.5) | 11.03 |
| 2024.04 | 161.3 | 162.6 | 137.0 | 144.5 (+3.1) | 9.69 |
| 2024.05 | 187.7 | 191.9 | 172.1 | 149.1 (+4.6) | 23.56 (SC25 peak) |
| 2024.06 | 184.3 | 190.2 | 164.1 | 152.7 (+3.6) | 10.24 |
| 2024.07 | 196.6 | 203.0 | 196.8 | 154.9 (+2.3) | 7.13 |
| 2024.08 | 246.1 (cycle peak) |
252.2 | 216.0 (SC25 peak) | 156.7 (+1.8) | 15.96 |
| 2024.09 | 195.7 | 197.8 | 141.1 | (159.5 projected, +2.8) | 15.36 |
| 2024.10 | 221.0 | 219.6 | 166.4 | (160.6 projected, +1.1) | 18.99 |
| 2024.11 | 199.6 | 195.3 | 152.5 | (158.0 projected, -2.6) | 9.33 |
| 2024.12 | 197.3 | 191.2 | 154.5 | (154.2 projected, -3.8) | 8.42 |
| 2025.01 | 190.3 | 184.2 | 137.0 | (148.7 projected, -5.5) | 13.17 |
| 2025.02 | 184.2 | 179.7 | 154.7 | (140.2 projected, -8.5) | 14.42 |
| 2025.03 | 155.6 (1) | 50.2 (2A) / 119.8 (2B) / 173.3 (2C) | (133.8 projected, -6.4) | (15.2) | |
| 2025.04 | (129.2 projected, -4.6) | ||||
| 2025.05 | (123.9 projected, -5.3) | ||||
| 2025.06 | (119.0 projected, -4.9) | ||||
| 2025.07 | (114.9 projected, -4.1) | ||||
| 2025.08 | (110.2 projected, -4.7) | ||||
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 27 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 activity has been on a slowly decreasing trend since September 2024 (using the average solar flux over 3 solar rotations as a proxy). Currently all 365 days smoothed indices are still indicating that a peak occurred on October 12 or 13, 2024. Should sunspot activity decrease even further then there is a possibility that the peak may have taken place in September 2024. Any peak outside of September-October 2024 appears unlikely. The 365 days average solar flux is likely to max out ~2% below the peak of solar cycle 23. The maximum 365d smoothed solar flux of SC23 and SC25 are similar, however, sunspot numbers were significantly lower during SC25 compared to SC23.
--------------------------------------------------------------------------------------
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.
