The geomagnetic field was quiet to active on March 20, partly due to weak effects from CH1135 and partly due to weak CME effects. Solar wind speed at SOHO ranged between 375 and 481 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. Solar wind speed and density at DSCOVR increased abruptly at 09:54 UT, likely signaling the onset of the disturbance related to the March 17 CME.
Solar flux density measured at 20h UT on 2.8 GHz was 156.1 - decreasing 4.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 137.77). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.9). Three hour interval K indices: 31124423 (planetary), 21024412 (Boulder), 50024515 (Andenes).
The background x-ray flux was at the class C1 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 279) and in 12 active regions using 1K resolution (SN: 184) SDO/HMI images.
Region 13251 [S13W73] decayed slowly and
quietly.
Region 13255 [S04W39] was quiet and stable.
Region 13256 [S22E36] decayed in the trailing spot section and was
mostly quiet after noon. C1 flares: C1.5 @ 13:53 UT
Region 13257 [S27E54] gained a small magnetic delta in the
northeastern part of the largest spot. An M class flare is possible. C1
flares: C1.7 @ 12:34, C1.4 @ 21:24 UT
Region 13258 [N19E19] developed slowly and was quiet.
Region 13259 [S16E57] was mostly quiet and stable.
Region 13260 [N23E58] was quiet and stable.
Spotted regions not observed (or interpreted
differently) by SWPC:
S8360 [N22W53] was quiet and stable.
S8370 [N24E10] was mostly quiet and stable.
S8377 [N26E39] was quiet and stable.
New region S8378 [N06E17] emerged before noon with tiny spots.
New region S8379 [S03W12] emerged before noon
with a tiny spot.
New region S8382 [S22W51] emerged with small spots and is developing
relatively quickly.
New region S8383 [N21E75] rotated into view with tiny spots.
New region S8384 [S11W06] was observed with tiny spots in an old
plage area.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C4.1 | 01:14 | 13256 | GOES16 | ||
| M1.2 | 01:48 | 13256 | GOES16 | LDE | |
| C3.1 | 07:43 | 13256 | GOES16 | ||
| C5.2/1F | 09:37 | S25E39 | 13256 | GOES16 | |
| C4.4 | 15:34 | S8370 | GOES16 | LDE | |
| C3.2 | 16:55 | 13257 | GOES16 | ||
| C2.0 | 19:04 | 13257 | GOES16 |
March 19-20: A large filament eruption covering an area just west of
the central meridian and from the southernmost part of the northern
hemisphere well into the southern hemisphere was observed beginning late on
March 19 peaking early on March 20. A slow and faint partial halo CME was
observed during the same time span, but any connection between these events
is uncertain. If they are associated the CME could reach Earth on March 23.
A fast partial halo CME was observed after the C4 flare in AR S8370. While
the main part of the ejecta is not headed towards Earth, there is a chance
that weak components of the CME will reach Earth on March 23.
March 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 recurrent southern hemisphere coronal hole (CH1135) rotated across the central meridian on March 16-17. A large southern hemisphere coronal hole (CH1136) will be Earth facing on March 20-21.
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.
Quiet to active geomagnetic conditions are likely on March 21 due to effects from CH1135 and the March 17 CME. Quiet to unsettled is likely on March 22. Quiet to minor storm conditions are possible on March 23-24 due to effects from CH1136 and CME effects.
| Coronal holes (1) | Coronal mass ejection (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 | ||||||||||
| 13251 | 2023.03.08 2023.03.09 |
1 | 3 | 2 | S13W75 | 0010 | AXX | AXX |
 |
 |
location: S13W73 |
| 13252 | 2023.03.09 2023.03.10 |
N13W77 |
location: N12W73 |
||||||||
| S8360 | 2023.03.11 | 2 | N22W53 | 0002 | BXO |
 |
 |
||||
| S8362 | 2023.03.13 | N08W47 | |||||||||
| 13255 | 2023.03.14 2023.03.14 |
1 | 1 | S05W47 | 0002 | AXX |
 |
 |
location: S04W39 | ||
| S8365 | 2023.03.14 | S18W31 | |||||||||
| S8366 | 2023.03.15 | S19W10 | |||||||||
| S8367 | 2023.03.16 | S29W24 | |||||||||
| 13256 | 2023.03.16 2023.03.17 |
6 | 33 | 19 | S20E39 | 0250 | EHO | FKO |
 |
 |
area: 0480 location: S22E36 |
| S8370 | 2023.03.17 | 13 | 5 | N24E10 | 0025 | BXO |
 |
 |
|||
| 13257 | 2023.03.18 2023.03.18 |
2 | 13 | 8 | S27E54 | 0140 | DSO | DKC |
 |
 |
beta-delta area: 0360 |
| 13259 | 2023.03.18 2023.03.19 |
3 | 20 | 8 | S21E46 | 0020 | CRO | DRI |
 |
 |
area: 0070 location: S16E57 SWPC location is far off |
| 13258 | 2023.03.18 | 2 | 12 | 8 | N19E18 | 0010 | AXX | DRI |
 |
 |
area: 0030 location: N19E19 |
| S8374 | 2023.03.18 | N28W27 | |||||||||
| 13260 | 2023.03.18 2023.03.19 |
1 | 7 | 4 | N24E58 | 0120 | HSX | DAO |
 |
 |
area: 0200 location: N23E58 |
| S8376 | 2023.03.18 | S43E20 | |||||||||
| S8377 | 2023.03.19 | 2 | N24E38 | 0002 | BXO |
 |
 |
||||
| S8378 | 2023.03.20 | 2 | N06E17 | 0004 | AXX |
 |
 |
||||
| S8379 | 2023.03.20 | 1 | 1 | S03W12 | 0003 | AXX |
 |
 |
|||
| S8380 | 2023.03.20 | S29E16 |
 |
||||||||
| S8381 | 2023.03.20 | S42E38 |
 |
||||||||
| S8382 | 2023.03.20 | 12 | 6 | S22W51 | 0050 | DRI |
 |
||||
| S8383 | 2023.03.20 | 6 | 1 | N21E75 | 0015 | BXO |
 |
||||
| S8384 | 2023.03.20 | 2 | 1 | S11W06 | 0004 | BXO |
 |
||||
| Total spot count: | 15 | 129 | 64 | ||||||||
| Sunspot number: | 75 | 279 | 184 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 38 | 163 | 98 | (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): | 83 | 153 | 147 | ||||||||
| 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 |
| 2021.08 | 77.7 | 79.7 | 22.0 | 35.4 (+4.0) | 6.19 |
| 2021.09 | 87.0 | 88.2 | 51.3 | 40.2 (+4.8) | 6.33 |
| 2021.10 | 88.9 | 88.3 | 37.4 | 45.2 (+5.0) | 7.38 |
| 2021.11 | 86.2 | 84.4 | 34.8 | 50.8 (+5.6) | 9.83 |
| 2021.12 | 103.0 | 99.8 | 67.5 | 55.9 (+5.1) | 6.40 |
| 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 | 77.2 (+4.2) | 7.48 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 80.9 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.5 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.3 (+5.8) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | (97.0 projected, +4.7) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.4 | (100.2 projected, +3.2) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 77.6 | (103.0 projected, +2.8) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 113.1 | (107.8 projected, +4.8) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | (113.8 projected, +6.0) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (118.9 projected, +5.1) | 14.48 (current SC25 peak) |
| 2023.03 | 160.1 (1) | 72.6 (2A) / 112.6 (2B) / 134.3 (2C) | (122.0 projected, +3.1) | (11.6) | |
| 2023.04 | (127.4 projected, +5.4) | ||||
| 2023.05 | (133.2 projected, +5.8) | ||||
| 2023.06 | (136.4 projected, +3.2) | ||||
| 2023.07 | (135.9 projected, -0.5) | ||||
| 2023.08 | (136.9 projected, +1.0) | ||||
| 2023.11 | (142.5 projected max SC25) | ||||
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: SIDC-SILSO.
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.
