The geomagnetic field was quiet to unsettled on March 22. Solar wind speed at SOHO ranged between 336 and 438 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at background levels at the end of the day. After the major flares in ARs 13914 and 13915 early on March 23, proton levels began to increase after 03:50 UT and the above 10 MeV proton flux is currently close to event levels. A corotating interaction region associated with CH1207 was observed reaching DSCOVR at 22:56 UT and a disturbance began early on March 23.
Solar flux density measured at 20h UT on 2.8 GHz was 197.6 - increasing 18.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 156.70. 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 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.5). Three hour interval K indices: 33331100 (planetary), 33332311 (Boulder), 43231001 (Andenes).
The background x-ray flux is at the class C5 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 342) and in 12 active regions using 1K resolution (SN: 231) SDO/HMI images.
Region 13607 [S19W84] decayed slowly and quietly.
Region 13608 [N09W81] decayed slowly and quietly.
Region 13614 [N16E06] decayed slowly losing
area and spots. A major long duration X1.1 event was recorded peaking at 01:33 UT on March 23. A
large asymmetrical full halo CME was observed after this event.
Region 13615 [S12E12] gained spots and area becoming one of the
largest spot groups of SC25. The region is very complex and could easily
produce further major flares. A major M5.0 flare was recorded at 02:36 UT.
Region 13617 [S13E44] produced a few C flares and decayed slowly.
Region 13618 [S19W76] was mostly quiet and stable as the spot group rotated
to the southwest limb.
Region 13619 [N19E44] was mostly quiet and stable.
New region 13620 [S09E74] rotated into view.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S9525 [N17W23] was quiet and stable.
S9528 [N19E60] was quiet and stable.
New region S9531 [N09W01] emerged with tiny spots.
New region S9533 [N05W09] emerged with a tiny spot.
New region S9534 [S04W14] emerged with tiny
spots.
New region S9535 [S08E26] was observed with tiny spots in an old
plage area.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.2 | 00:19 | 13615 | GOES16 | ||
| C3.5 | 00:55 | 13615 | GOES16 | ||
| C3.3 | 01:17 | N14E19 | 13614 | GOES16 | |
| C2.6 | 02:17 | 13615 | GOES16 | ||
| C2.2 | 02:40 | 13615 | GOES16 | ||
| C2.4 | 03:43 | 13615 | GOES16 | ||
| C2.5 | 03:59 | 13615 | GOES16 | ||
| C2.8 | 04:34 | 13615 | GOES18 | ||
| C3.6 | 04:55 | S13E27 | 13615 | GOES18 | |
| C5.7 | 05:16 | S15E26 | 13615 | GOES18 | |
| C5.4 | 05:21 | 13619 | GOES18 | ||
| C3.6 | 05:54 | 13614 | GOES16 | ||
| C3.6 | 06:42 | behind northeast limb | GOES16 | ||
| C3.5 | 07:14 | behind northeast limb | GOES16 | ||
| C2.5 | 08:14 | 13615 | GOES16 | ||
| C2.4 | 08:51 | 13618 | GOES16 | ||
| C2.3 | 09:27 | 13615 | GOES16 | ||
| C3.2 | 10:53 | 13615 | GOES16 | ||
| C4.3 | 11:16 | S17E49 | 13617 | GOES16 | |
| C3.0 | 12:15 | 13615 | GOES16 | ||
| C6.0/1F | 13:27 | N14E09 | 13614 | GOES16 | |
| C6.2 | 13:35 | 13614 | GOES16 | ||
| C8.4 | 13:58 | 13614 | GOES16 | ||
| C6.4 | 14:41 | N20E14 | 13614 | GOES16 | |
| C3.6 | 15:30 | behind northeast limb | GOES16 | ||
| C3.5 | 16:13 | 13615 | GOES16 | simultaneous flare in AR 13618 | |
| C4.1 | 16:29 | 13615 | GOES16 | ||
| C4.9 | 16:57 | 13617 | GOES16 | ||
| C3.5 | 17:44 | 13617 | GOES16 | ||
| C3.8 | 18:21 | 13615 | GOES16 | ||
| C3.6 | 19:09 | 13615 | GOES16 | ||
| C3.4 | 19:38 | 13615 | GOES16 | ||
| C5.2 | 20:04 | 13615 | GOES16 | ||
| C5.9 | 20:12 | 13615 | GOES16 | ||
| M4.3/2B | 20:32 | 13615 | GOES16 | ||
| M1.1 | 21:22 | S14E18 | 13615 | GOES16 | |
| C5.9 | 21:40 | 13615 | GOES16 | ||
| C7.4 | 22:55 | 13615 | GOES16 | ||
| C8.5 | 23:24 | behind northeast limb | GOES16 | LDE | |
| C8.3 | 23:58 | S15E15 | 13615 | GOES16 |
March 20-22: 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 could
reach Earth sometime between late on March 24 and noon on March 25 and cause
active to severe storm conditions.
[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 negative polarity southern hemisphere coronal hole (CH1207) rotated across the central meridian on March 20-22.
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 23-24 due to effects associated with CH1207 due to CME effects. The March 23 CME could reach Earth between late on March or noon on March 25 and cause active to severe storm conditions lasting until March 26 or 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 | ||||||||||
| 13608 | 2024.03.10 2024.03.13 |
2 | 2 | N11W81 | 0010 | BXO | AXX |
 |
 |
||
| 13609 | 2024.03.11 | N06W82 | location: N05W69 | ||||||||
| 13607 | 2024.03.11 2024.03.13 |
2 | 2 | 1 | S18W91 | 0150 | DSO | AXX |
 |
 |
location: S19W84 area: 0020 |
| 13610 | 2024.03.12 2024.03.13 |
S16W57 | location: S15W46 | ||||||||
| 13611 | 2024.03.13 2024.03.14 |
N28W46 |
 |
location: N29W40 |
|||||||
| 13616 | 2024.03.16 2024.03.18 |
1 | N03W88 | 0010 | BXO |
 |
rotated out of view mismatch between SWPC spot count and classification |
||||
| 13614 | 2024.03.16 2024.03.17 |
4 | 27 | 14 | N17E03 | 0210 | DSO | DSO |
 |
 |
area: 0270 location: N16E06 |
| 13615 | 2024.03.17 2024.03.18 |
52 | 110 | 62 | S13E10 | 0370 | EKC | FKC |
 |
 |
beta-gamma-delta area: 1270 location: S12E12 |
| S9513 | 2024.03.17 | S15W48 | |||||||||
| S9514 | 2024.03.17 | S30W36 | |||||||||
| S9515 | 2024.03.17 | N09E06 | |||||||||
| S9518 | 2024.03.18 | N26W56 | |||||||||
| S9519 | 2024.03.18 | N09W19 | |||||||||
| 13618 | 2024.03.19 2024.03.21 |
6 | 7 | 5 | S19W77 | 0100 | CAO | DAO |
 |
 |
location: S19W76 |
| 13617 | 2024.03.19 2024.03.20 |
6 | 14 | 7 | S14E41 | 0100 | CAO | CAO |
 |
 |
location: S13E44 |
| S9525 | 2024.03.20 | 9 | 3 | N17W23 | 0020 | BXO |
 |
 |
|||
| 13619 | 2024.03.20 2024.03.21 |
5 | 12 | 6 | N20E46 | 0100 | CAO | CAO |
 |
 |
location: N19E44 area: 0150 |
| S9528 | 2024.03.21 | 3 | 2 | N19E60 | 0010 | AXX |
 |
 |
|||
| S9529 | 2024.03.21 | S22E06 |
 |
||||||||
| S9530 | 2024.03.21 | N37W07 |
 |
||||||||
| S9531 | 2024.03.22 | 7 | 5 | N09W01 | 0015 | BXO |
 |
||||
| 13620 | 2024.03.22 2024.03.22 |
3 | 4 | 3 | S10E74 | 0030 | CRO | CAO |
 |
was AR S9532 area: 0060 |
|
| S9533 | 2024.03.22 | 1 | N05W09 | 0002 | AXX |
 |
was AR S9527 | ||||
| S9534 | 2024.03.22 | 2 | 2 | S04W14 | 0005 | BXO |
 |
||||
| S9535 | 2024.03.22 | 2 | 1 | S08E26 | 0005 | AXX |
 |
||||
| Total spot count: | 81 | 202 | 111 | ||||||||
| Sunspot number: | 171 | 342 | 231 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 119 | 237 | 146 | (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): | 188 | 188 | 185 | ||||||||
| 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 | 146.6 (1) | 71.1 (2A) / 100.2 (2B) / 126.4 (2C) | (116.9 projected, -0.6) | (8.1) | |
| 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.
