The geomagnetic field was unsettled to very severe storm on March 24. The March 23 CME was observed reaching SOHO at 14:07 UT with a strong solar wind shock. Initially the Bz component of the IMF was strongly southwards, then swung northwards after 18h UT and have remained northwards since then. This caused the geomagnetic disturbance to become less severe than it could have been, even so very severe geomagnetic storming was recorded during the 15-18h UT interval. The high latitude magnetometer at Andenes recorded unsettled to very severe storm levels. The above 10 MeV proton flux was at 40 pfu at the end of the day, weakening significantly after the CME impact.
Solar flux density measured at 20h UT on 2.8 GHz was 195.1 - increasing 23.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 156.94. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.71 on June 27, 2023). The Potsdam WDC planetary A index was 69 (STAR Ap - based on the mean of three hour interval ap indices: 69.0). Three hour interval K indices: 53446864 (planetary), 43445854 (Boulder), 55345865 (Andenes).
The background x-ray flux is at the class C2 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 329) and in 10 active regions using 1K resolution (SN: 211) SDO/HMI images.
Region 13614 [N17W20] decayed slowly losing
area and spots.
Region 13615 [S12W14] lost some magnetic delta structures, however,
there are still several left, both in the leading, intermediate and trailing
spot sections. Major flares are possible.
Region 13617 [S13E18] developed minor polarity intermixing and could
produce C flares.
Region 13619 [N18E17] gained a few spots and was quiet.
Region 13620 [S09E48] was mostly quiet and stable.
Region 13621 [N18W55] was quiet and stable.
New region 13622 [N20E63] rotated into view on March 23 and was
numbered the next day by SWPC.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S9528 [N20E35] was quiet and stable.
S9529 [S18W21] gained spots and was quiet.
New region S9539 [S13E37] was observed with tiny spots in an old
plage area.
New region S9540 [S11E72] emerged with tiny
spots.
New region S9541 [S09W46] emerged with a tiny spot.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C9.9 | 01:04 | 13615 | GOES16 | ||
| M1.4 | 01:25 | 13615 | GOES16 | ||
| M2.1 | 01:54 | 13615 | GOES16 | ||
| M2.3 | 02:05 | 13615 | GOES16 | ||
| M2.7 | 02:18 | 13615 | GOES16 | ||
| M1.9 | 02:52 | behind southwest limb | 13618 | GOES16 | |
| M1.0 | 03:33 | 13617 | GOES16 | ||
| M1.4 | 03:43 | 13615 | GOES16 | ||
| M1.1 | 04:03 | 13615 | GOES16 | ||
| C5.1 | 04:18 | 13615 | GOES18 | ||
| C3.8 | 04:44 | 13615 | GOES18 | ||
| C3.1 | 05:14 | 13615 | GOES18 | ||
| C4.2 | 05:45 | 13615 | GOES18 | ||
| C5.2 | 06:01 | 13615 | GOES18 | ||
| M2.2/1B | 06:06 | S14W03 | 13615 | GOES16 | |
| C7.2 | 07:18 | 13615 | GOES16 | ||
| C8.2 | 07:25 | 13615 | GOES16 | ||
| M1.3 | 07:50 | 13615 | GOES16 | ||
| C6.2 | 08:33 | 13615 | GOES16 | ||
| C6.2 | 08:44 | 13622 | GOES16 | ||
| C4.9 | 09:04 | 13615 | GOES16 | ||
| C4.8 | 09:17 | 13615 | GOES16 | ||
| C7.4 | 09:25 | 13615 | GOES16 | ||
| C9.5/1N | 09:52 | S15W01 | 13615 | GOES16 | |
| C6.6 | 09:59 | 13615 | GOES16 | ||
| C4.8 | 10:41 | 13615 | GOES16 | ||
| C9.7/1F | 11:17 | S13W04 | 13615 | GOES16 | |
| M1.1/1N | 12:18 | 13615 | GOES16 | ||
| C7.8 | 12:29 | 13615 | GOES16 | ||
| M1.0 | 12:34 | 13615 | GOES16 | ||
| M1.2 | 13:13 | 13615 | GOES16 | ||
| C5.4 | 13:37 | 13615 | GOES16 | ||
| C3.9 | 14:13 | 13615 | GOES16 | ||
| C3.5 | 14:38 | 13615 | GOES16 | ||
| C5.2 | 14:45 | S13W07 | 13615 | GOES16 | |
| C3.9 | 15:06 | 13615 | GOES16 | ||
| C5.3 | 15:21 | S15W06 | 13615 | GOES16 | |
| C4.5 | 16:09 | 13615 | GOES16 | ||
| C7.3 | 16:15 | 13615 | GOES16 | ||
| C4.8 | 16:28 | 13615 | GOES16 | ||
| C4.3 | 17:31 | 13615 | GOES16 | ||
| C5.6 | 17:45 | 13615 | GOES16 | ||
| C4.1 | 18:36 | 13615 | GOES16 | ||
| C3.7 | 19:24 | 13615 | GOES16 | ||
| C4.6 | 19:31 | 13615 | GOES16 | ||
| C4.4 | 20:19 | 13620 | GOES16 | ||
| C4.1 | 20:26 | 13615 | GOES16 | ||
| C3.2 | 21:33 | 13615 | GOES16 | ||
| C3.5 | 22:05 | 13615 | GOES16 | ||
| C3.6 | 22:36 | 13615 | GOES16 | ||
| C2.6 | 23:56 | 13615 | GOES16 |
March 22, 24: No obviously Earth directed CMEs were observed.
March 23: An asymmetrical full halo CME was
observed after the X1.1 flare in AR 13614 early in the day. The CME reached
Earth before 15h UT on March 24, a transition time of approx. 37 hours.
[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]
No obvious coronal hole are currently in or near Earth facing positions.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is very poor. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to minor storm on March 25 with a chance of major and severe storm intervals should the Bz component of the IMF swing strongly southwards. Quiet to unsettled conditions are likely on March 26-27.
| 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 | ||||||||||
| 13610 | 2024.03.12 2024.03.13 |
S16W85 | location: S15W72 | ||||||||
| 13611 | 2024.03.13 2024.03.14 |
N28W74 |
location: N29W66 |
||||||||
| 13614 | 2024.03.16 2024.03.17 |
3 | 18 | 6 | N17W21 | 0150 | DSO | CSO |
 |
 |
area: 0240 location: N17W20 |
| 13615 | 2024.03.17 2024.03.18 |
54 | 112 | 71 | S13W14 | 0810 | FKC | FKC |
 |
 |
beta-gamma-delta area: 1790 location: S12W14 |
| S9515 | 2024.03.17 | N09W20 | |||||||||
| S9519 | 2024.03.18 | N09W45 | |||||||||
| 13617 | 2024.03.19 2024.03.20 |
5 | 15 | 9 | S13E17 | 0060 | CAO | CAO |
 |
 |
beta-gamma location: S13E18 |
| 13621 | 2024.03.20 2024.03.23 |
3 | 7 | 3 | N17W52 | 0020 | CSO | CRO |
 |
 |
location: N18W55 area: 0030 |
| 13619 | 2024.03.20 2024.03.21 |
3 | 21 | 7 | N19E16 | 0100 | CSO | CAO |
 |
 |
beta-gamma location: N18E17 area: 0170 |
| S9528 | 2024.03.21 | 3 | 1 | N22E35 | 0007 | BXO |
 |
 |
|||
| S9529 | 2024.03.21 | 13 | 6 | S18W21 | 0030 | CRO |
 |
 |
|||
| S9530 | 2024.03.21 | N37W33 | |||||||||
| S9531 | 2024.03.22 | N09W27 | |||||||||
| 13620 | 2024.03.22 2024.03.22 |
2 | 6 | 3 | S10E46 | 0030 | HAX | CAO |
 |
 |
area: 0050 location: S09E48 |
| S9533 | 2024.03.22 | N05W35 | was AR S9527 | ||||||||
| S9534 | 2024.03.22 | S04W40 | |||||||||
| S9535 | 2024.03.22 | S08W00 | |||||||||
| 13622 | 2024.03.23 2024.03.24 |
5 | 9 | 4 | N19E61 | 0060 | DAO | CAO |
 |
 |
location: N20E63 |
| S9537 | 2024.03.23 | S10W00 |
 |
||||||||
| S9538 | 2024.03.23 | S28E10 |
 |
||||||||
| S9539 | 2024.03.24 | 2 | 1 | S13E37 | 0005 | AXX |
 |
||||
| S9540 | 2024.03.24 | 2 | S11E72 | 0002 | BXO |
 |
|||||
| S9541 | 2024.03.24 | 1 | S09W46 | 0001 | AXX |
 |
|||||
| Total spot count: | 75 | 209 | 111 | ||||||||
| Sunspot number: | 145 | 329 | 211 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 115 | 250 | 152 | (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): | 160 | 181 | 169 | ||||||||
| 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 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.6 (+5.9) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.5 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.9 (+2.4) | 11.16 |
| 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 (current SC25 peak) |
| 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 | 124.1 (+1.2) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 160.5 | 125.2 (+1.1) (SC25 solar max candidate) |
8.95 |
| 2023.07 | 176.4 | 182.2 | 160.0 | 124.3 (-0.9) | 8.15 |
| 2023.08 | 153.7 | 157.6 | 114.8 | 124.0 (-0.3) | 7.19 |
| 2023.09 | 154.4 | 156.0 | 134.2 | (124.2 projected, +0.2) | 14.26 |
| 2023.10 | 142.8 | 141.9 | 99.4 | (125.0 projected, +0.8) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 105.4 | (125.0 projected, -0.0) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 114.2 | (121.7 projected, -3.3) | 9.60 |
| 2024.01 | 164.6 | 159.3 | 123.0 | (118.3 projected, -3.4) | 5.46 |
| 2024.02 | 172.5 | 168.3 | 124.6 | (117.5 projected, -0.8) | 5.31 |
| 2024.03 | 151.3 (1) | 80.5 (2A) / 104.0 (2B) / 128.3 (2C) | (116.9 projected, -0.6) | (11.7) | |
| 2024.04 | (116.9 projected, -0.0) | ||||
| 2024.05 | (118.1 projected, +1.2) | ||||
| 2024.06 | (117.3 projected, -0.8) | ||||
| 2024.07 | (115.6 projected, -1.7) | ||||
| 2024.08 | (113.7 projected, -1.9) | ||||
| 2024.09 | (112.0 projected, -1.7) | ||||
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 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
Solar activity saw a significant decrease during the latter half of February and the first part of March. While there is still a chance that there could be another and higher peak in October or November 2023, chances that June 2023 was solar max has increased. After November 2023 there is currently no other obvious candidate solar max month. Taking into account the state of the solar polar fields another major peak during SC25 is becoming less likely.
--------------------------------------------------------------------------------------
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.
