The geomagnetic field was quiet to unsettled on March 26 due to lingering CME effects. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at 2.5 pfu at the end of the day.
Solar flux density measured at 20h UT on 2.8 GHz was 178.2 - increasing 10.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.08. 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 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.8). Three hour interval K indices: 33132233 (planetary), 33133223 (Boulder), 55233354 (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: 291) and in 11 active regions using 1K resolution (SN: 202) SDO/HMI images.
Region 13614 [N17W46] decayed slowly and quietly.
Region 13615 [S12W39] decayed slowly losing area and a few spots. The
trailing spot section continued to drift slowly apart from the rest of the
spot group. The magnetic delta structure in the leading spot
section disappeared. There are still significant magnetic
deltas within the intermediate and trailing spot sections. Major flaring is possible.
C1 flares: C1.9 @ 07:55 UT
Region 13617 [S13W08] decayed slowly and quietly.
Region 13619 [N18W10] developed slowly and quietly.
Region 13620 [S09E21] decayed slowly and quietly.
Region 13621 [N17W78] rotated partly out of view and produced several
flares.
Region 13622 [N20E36] decayed slowly and quietly.
Region 13623 [S18W46] decayed slowly and quietly.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S9528 [N21E08] reemerged with tiny spots.
New region S9542 [S23E18] emerged with tiny spots.
New region S9543 [N09E13] emerged with a tiny
spot.
New region S9544 [N05W32] emerged with a tiny spot.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.9 | 00:15 | 13615 | GOES16 | ||
| M1.8 | 00:36 | S13W36 | 13615 | GOES16 | |
| C3.1 | 00:47 | 13615 | GOES16 | ||
| C5.3 | 01:15 | S13W33 | 13615 | GOES16 | |
| C5.1 | 02:26 | 13615 | GOES16 | ||
| C3.0 | 03:03 | 13615 | GOES16 | ||
| C2.1 | 03:12 | 13615 | GOES16 | ||
| C2.1 | 03:26 | 13615 | GOES16 | ||
| C3.5 | 03:54 | 13621 | GOES16 | attributed to simultaneous flare in AR 13615 by SWPC | |
| C2.4 | 04:37 | 13615 | GOES18 | ||
| C2.4 | 05:36 | 13615 | GOES18 | ||
| C3.0 | 06:22 | S13W37 | 13615 | GOES16 | |
| C2.3 | 06:56 | 13615 | GOES16 | ||
| C2.1 | 07:29 | 13615 | GOES16 | ||
| C2.4 | 08:11 | 13615 | GOES16 | ||
| C3.7 | 08:32 | S13W37 | 13615 | GOES16 | simultaneous flare in AR 13621 |
| C4.5 | 09:03 | 13621 | GOES16 | ||
| C3.6 | 09:19 | 13621 | GOES16 | ||
| C2.2 | 09:52 | 13621 | GOES16 | ||
| C2.1 | 10:07 | 13615 | GOES16 | ||
| M1.0 | 10:17 | 13615 | GOES16 | ||
| M1.3 | 10:43 | 13615 | GOES16 | ||
| C2.2 | 11:17 | 13615 | GOES16 | ||
| C3.2 | 11:34 | 13615 | GOES16 | ||
| C2.3 | 11:45 | 13615 | GOES16 | ||
| C4.2 | 12:15 | 13615 | GOES16 | ||
| C4.3 | 12:23 | 13615 | GOES16 | ||
| C4.7 | 12:28 | 13615 | GOES16 | ||
| C6.4 | 12:49 | 13615 | GOES16 | ||
| M1.9 | 13:30 | 13615 | GOES16 | ||
| M1.7 | 13:46 | 13621 | GOES16 | incorrectly attributed to R 13615 by SWPC | |
| C7.2 | 14:19 | 13615 | GOES16 | ||
| C5.5 | 14:48 | 13615 | GOES16 | ||
| C5.8 | 15:01 | 13615 | GOES16 | ||
| C2.2 | 15:41 | 13615 | GOES16 | ||
| C2.1 | 16:25 | 13615 | GOES16 | ||
| C2.5 | 16:50 | 13615 | GOES16 | ||
| C3.7 | 17:15 | 13615 | GOES16 | ||
| C3.5 | 17:37 | 13615 | GOES16 | ||
| C3.0 | 18:29 | 13615 | GOES16 | ||
| C3.1 | 18:43 | 13615 | GOES16 | ||
| C3.8 | 18:59 | 13615 | GOES16 | ||
| C3.1 | 19:41 | 13615 | GOES16 | ||
| C6.8 | 19:52 | 13615 | GOES16 | ||
| C5.5 | 20:14 | 13615 | GOES16 | ||
| C2.3 | 20:48 | 13614 | GOES16 | ||
| C2.0 | 21:33 | 13615 | GOES16 | ||
| M1.6 | 21:58 | 13615 | GOES16 | ||
| C3.1 | 22:33 | 13615 | GOES16 | ||
| C2.5 | 23:04 | 13615 | GOES16 | ||
| C8.5 | 00:01 (flare began 23:43) | 13615 | GOES16 |
March 24-25: 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]
A positive polarity trans equatorial coronal hole (CH1209) will be Earth facing on March 27. A positive polarity southern hemisphere coronal hole (CH1208) will be Earth facing on March 27-28.
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 to unsettled on March 27 and quiet on March 28-29. Quiet to unsettled is possible on March 30-31 due to effects from CH1208 and CH1209.
| 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 | ||||||||||
| 13614 | 2024.03.16 2024.03.17 |
1 | 4 | 1 | N18W48 | 0080 | HSX | CSO |
 |
 |
area: 0230 location: N17W46 |
| 13615 | 2024.03.17 2024.03.18 |
53 | 102 | 55 | S13W41 | 1140 | FKC | FKC |
 |
 |
beta-gamma-delta area: 1530 location: S12W39 |
| S9515 | 2024.03.17 | N09W46 | |||||||||
| 13617 | 2024.03.19 2024.03.20 |
1 | 6 | 2 | S14W10 | 0050 | HSX | CSO |
 |
 |
location: S13W08 |
| 13621 | 2024.03.20 2024.03.23 |
3 | 2 | 1 | N15W80 | 0040 | CSO | CRO |
 |
 |
location: N17W78 |
| 13619 | 2024.03.20 2024.03.21 |
7 | 21 | 14 | N19W10 | 0140 | CSO | DSO |
 |
 |
location: N18W10 area: 0220 |
| S9528 | 2024.03.21 | 15 | 8 | N21E08 | 0025 | CRO |
 |
||||
| 13623 | 2024.03.21 2024.03.25 |
1 | 2 | 1 | S19W47 | 0010 | AXX | CRO |
 |
 |
area: 0006 location: S18W46 |
| S9530 | 2024.03.21 | N37W59 | |||||||||
| S9531 | 2024.03.22 | N09W53 | |||||||||
| 13620 | 2024.03.22 2024.03.22 |
1 | 6 | 3 | S08E19 | 0020 | HRX | CRO |
 |
 |
location: S09E21 |
| 13622 | 2024.03.23 2024.03.24 |
2 | 9 | 4 | N19E32 | 0010 | BXO | CRO |
 |
 |
location: N20E36 area: 0015 |
| S9537 | 2024.03.23 | S10W26 | |||||||||
| S9538 | 2024.03.23 | S28W16 | |||||||||
| S9539 | 2024.03.24 | S13E11 | |||||||||
| S9540 | 2024.03.24 | S11E46 | |||||||||
| S9542 | 2024.03.26 | 2 | 2 | S23E18 | 0010 | CRO |
 |
||||
| S9543 | 2024.03.26 | 1 | 1 | N09E13 | 0002 | AXX |
 |
||||
| S9544 | 2024.03.26 | 1 | N05W32 | 0001 | AXX |
 |
|||||
| Total spot count: | 69 | 171 | 92 | ||||||||
| Sunspot number: | 149 | 291 | 202 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 102 | 214 | 135 | (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): | 179 | 160 | 162 | ||||||||
| 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 | 153.8 (1) | 90.5 (2A) / 108.0 (2B) / 129.9 (2C) | (116.9 projected, -0.6) | (12.2) | |
| 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.
