The geomagnetic field was quiet to unsettled on April 9. Solar wind speed at SOHO ranged between 318 and 381 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels. What was likely a co-rotating interaction region associated with CH1140 began to dominate the solar wind late on April 9 and caused unsettled to active conditions early on April 10.
Solar flux density measured at 20h UT on 2.8 GHz was 140.3 - decreasing 3.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 138.77). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.9). Three hour interval K indices: 31111112 (planetary), 20112212 (Boulder), 42012224 (Andenes).
The background x-ray flux is at the class C1 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 190) and in 9 active regions using 1K resolution (SN: 161) SDO/HMI images.
Region 13269 [S24W47] decayed slowly and quietly.
Region 13272 [S21E37] decayed slowly early in
the day, but gained spots again later in the day. A small magnetic delta
formed in a central southern penumbra. The region has polarity intermixing and
M class flare potential. C1 flares: C1.0 @ 00:53, C1.4 @ 01:36, C1.8 @
02:29, C1.4 @ 04:04, C1.8 @ 10:55, C1.3 @ 17:40, C1.7 @ 21:52 UT
New region 13273 [N09E27] emerged quickly before noon and developed
all day. C flares are likely. C1 flares: C1.6 @ 05:05, C1.6 @ 07:56, C1.1 @
09:32, C1.7 @ 13:17, C1.4 @ 17:58, C1.5 @ 19:40, C1.5 @ 23:50 UT
Spotted regions not observed (or interpreted
differently) by SWPC:
S8418 [S11W64] decayed slowly and quietly.
S8429 [S24W08] was quiet and stable.
S8437 [S13W07] was quiet and stable.
S8440 [S07E12] developed slowly and quietly.
S8442 [N13E07] was quiet and stable.
New region S8444 [N19E77] rotated into view and was mostly quiet.
New region S8445 [N24E44] was observed with a tiny spot in an old
plage area.
New region S8446 [N27E23] was observed with a tiny spot in an old
plage area.
New region S8447 [S09E33] emerged with tiny spots.
New region S8448 [N13W13] was observed with tiny spots in an old
plage area.
AR S8449 [S21E83 @ 06:15 on April 10] was numbered early on April 10 and produced an M2.8 flare at 05:20 UT. C1 flares: C1.6 @ 03:04, C1.7 @ 07:38 UT
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C9.1 | 06:08 | S18E47 | 13272 | GOES16 | |
| C3.2 | 14:53 | S19E42 | 13272 | GOES16 | simultaneous flare in AR 13273 |
| C2.7 | 15:10 | 13272 | GOES16 | ||
| C2.4 | 16:28 | N10E31 | 13273 | GOES16 | |
| C2.8 | 16:35 | SE limb | S8449 | GOES16 | |
| C3.5 | 18:27 | S22E42 | 13272 | GOES16 | |
| C3.7 | 18:41 | S22E42 | 13272 | GOES16 | |
| C2.0 | 19:23 | N10E30 | 13273 | GOES16 | |
| C2.7 | 21:19 | SE limb | S8449 | GOES16 | |
| C2.4 | 21:34 | SE limb | S8449 | GOES16 | simultaneous flare in AR 13273 |
| C2.2 | 22:45 | SE limb | S8449 | GOES16 | |
| C2.0 | 23:19 | 13272 | GOES16 |
April 9: A filament eruption in the
southwest quadrant was observed beginning in SDO/AIA imagery at 19:06 UT and
peaked 40 minutes later. A partial halo CME was observed in LASCO C2 imagery
from 20:00 UT. There is a chance components of this CME will reach Earth on
April 12 or 13.
April 8: No obviously Earth directed CMEs were
observed.
April 7: A filament eruption across AR 13269 began at 07:34 in
SDO/AIA imagery and peaked just after 09h UT. Coronal dimming was observed,
however, no obvious Earth directed CME was seen in subsequent LASCO C2 imagery. Several
CMEs were observed during the day, however, most of them appeared to be backsided.
[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 northern hemisphere coronal hole (CH1140) was Earth facing on April 7-8.
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 conditions are likely on April 10-12 due to effects from CH1140.
| 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 | ||||||||||
| 13269 | 2023.03.30 2023.04.02 |
1 | S25W54 | 0002 | AXX |
 |
 |
location: S24W47 | |||
| S8418 | 2023.04.01 | 2 | S11W64 | 0002 | BXO |
 |
 |
||||
| 13271 | 2023.04.02 2023.04.04 |
S16W87 | location: S17W84 | ||||||||
| S8426 | 2023.04.03 | N33W56 | |||||||||
| S8428 | 2023.04.04 | N19W42 | |||||||||
| S8429 | 2023.04.04 | 14 | 4 | S24W08 | 0020 | BXO |
 |
 |
|||
| S8430 | 2023.04.05 | N28W02 | |||||||||
| S8431 | 2023.04.05 | S21W53 | |||||||||
| S8432 | 2023.04.05 | S14W31 | |||||||||
| 13272 | 2023.04.05 2023.04.06 |
24 | 67 | 43 | S21E37 | 0280 | EAI | FAI |
 |
 |
beta-gamma-delta area: 0400 |
| S8434 | 2023.04.05 | S07E17 | |||||||||
| S8435 | 2023.04.06 | S27W17 | |||||||||
| S8437 | 2023.04.06 | 4 | S13W07 | 0010 | AXX |
 |
 |
||||
| S8438 | 2023.04.06 | N14W10 | |||||||||
| S8439 | 2023.04.07 | S24E16 |
 |
||||||||
| S8440 | 2023.04.08 | 7 | 3 | S07E12 | 0020 | CRO |
 |
 |
|||
| S8442 | 2023.04.08 | 3 | 2 | N13E07 | 0007 | BXO |
 |
 |
|||
| 13273 | 2023.04.09 2023.04.09 |
8 | 32 | 14 | N10E27 | 0050 | CAO | DAI |
 |
was AR S8443 location: N09E27 area: 0150 |
|
| S8444 | 2023.04.09 | 1 | 1 | N19E77 | 0080 | HSX |
 |
||||
| S8445 | 2023.04.09 | 1 | 1 | N24E44 | 0003 | AXX |
 |
||||
| S8446 | 2023.04.09 | 5 | 2 | N27E23 | 0010 | AXX |
 |
||||
| S8447 | 2023.04.09 | 2 | 1 | S09E33 | 0004 | BXO |
 |
||||
| S8448 | 2023.04.09 | 3 | N13W13 | 0005 | AXX |
 |
|||||
| S8449 | 2023.04.10 | S21E83 @ 06:15 |
 |
||||||||
| Total spot count: | 32 | 142 | 71 | ||||||||
| Sunspot number: | 52 | 272 | 161 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 42 | 160 | 89 | (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): | 57 | 150 | 129 | ||||||||
| 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 |
| 2021.09 | 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 | 77.4 (+4.4) | 7.48 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 81.1 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.7 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.5 (+5.8) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.4 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | (99.0 projected, +2.6) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | (102.0 projected, +3.0) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | (106.8 projected, +4.8) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | (112.9 projected, +6.1) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (117.9 projected, +5.0) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (121.0 projected, +3.1) | 14.42 |
| 2023.04 | 134.2 (1) | 12.9 (2A) / 42.9 (2B) / 119.8 (2C) | (126.4 projected, +5.4) | (9.7) | |
| 2023.05 | (132.1 projected, +5.7) | ||||
| 2023.06 | (135.2 projected, +3.1) | ||||
| 2023.07 | (134.7 projected, -0.5) | ||||
| 2023.08 | (135.7 projected, +1.0) | ||||
| 2023.09 | (139.2 projected, +3.5) | ||||
| 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.
