The geomagnetic field was at quiet levels on September 9. Solar wind speed at SOHO ranged between 326 and 513 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at 29 pfu at the end of the day having peaked at 34 pfu at 22:50 UT. The proton event was most likely caused by one or several of the flares in AR 13806 behind the southwest limb during the first half of the day.
Solar flux density measured at 20h UT on 2.8 GHz was 214.8 - decreasing 45.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 175.26. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 175.26 on March 11, 2024). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.9). Three hour interval K indices: 21211222 (planetary), 22322333 (Boulder), 33111335 (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 13 active regions using 2K resolution (SN: 359) and in 12 active regions using 1K resolution (SN: 222) SDO/HMI images.
AR 13811 [S12W47] produced a single M flare and
was otherwise mostly quiet.
AR 13813 [S23W26] decayed slowly and quietly. AR S10105 were split
off.
AR 13814 [N15E12] developed and gained a magnetic delta
configuration. The region produced M flares during the latter half of the
day. Taking into consideration the rapid development of neighboring AR 13822
a major flare is possible.
AR 13815 [S25W17] decayed slowly and quietly.
AR 13816 [S10W22] decayed slowly and quietly.
AR 13821 [N14W51] decayed slowly and quietly.
New AR 13822 [N14E23] emerged rapidly just north of AR S10101 and
merged with that spot group late in the day. M flares are likely.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S10095 [N19W23] decayed slowly and quietly losing all leading
polarity spots.
S10096 [N17W02] was quiet and stable.
S10097 [S18E12] was quiet and stable.
S10098 [N01W16] reemerged with tiny spots.
S10104 [S11W28] was quiet and stable.
New region S10105 [S18W33] was split off from AR 13813 and has only
tiny spots.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.6 | 00:12 | 13811 | GOES16 | ||
| C7.8 | 02:31 | southwest limb | 13806 | GOES16 | |
| C9.7 | 02:37 | southwest limb | 13806 | GOES16 | |
| M1.0 | 03:28 | southwest limb | 13806 | GOES16 | LDE |
| M1.2 | 05:30 | 13815 | GOES16 | ||
| M1.8 | 05:45 | southwest limb | 13806 | GOES16 | |
| C8.8 | 06:20 | southwest limb | 13806 | GOES16 | |
| C7.3 | 07:16 | southwest limb | 13806 | GOES16 | |
| C6.5 | 07:28 | 13815 | GOES16 | ||
| M1.0 | 08:38 | southwest limb | 13806 | GOES16 | |
| M1.5 | 08:50 | southwest limb | 13806 | GOES16 | |
| M1.1 | 09:26 | southwest limb | 13806 | GOES16 | |
| M1.7 | 10:27 | southwest limb | 13806 | GOES16 | LDE |
| M1.0 | 12:17 | 13811 | GOES16 | ||
| C9.9 | 12:43 | 13811 | GOES16 | ||
| C7.0 | 13:07 | southwest limb | 13806 | GOES16 | |
| C5.7 | 13:58 | southwest limb | 13806 | GOES16 | |
| C6.2 | 14:05 | southwest limb | 13806 | GOES16 | |
| C5.3 | 15:07 | southwest limb | 13806 | GOES16 | |
| C3.7 | 16:46 | 13811 | GOES16 | ||
| M3.4/2N | 17:08 | 13814 | GOES16 | ||
| C4.4 | 17:54 | 13811 | GOES16 | ||
| C4.5 | 19:21 | southwest limb | 13806 | GOES16 | |
| C3.8 | 20:30 | 13814 | GOES16 | ||
| C3.8 | 22:07 | 13811 | GOES16 | ||
| M1.2 | 00:11 (flare began at 23:24 UT) | 13814 | GOES16 | partial halo CME |
September 9-10: A partial halo CME was observed most off the northern
hemisphere limbs and the north pole following a long duration M class event
in AR 13814. This event peaked at 00:16 UT on September 10. A very
impressive backsided full halo CME was observed starting at 05:24 UT on
Sept.9 in LASCO imagery, the source was likely 2-3 days behind the northeast
limb.
September 8: No obviously Earth directed CMEs were observed.
September 7: A partial halo CME was observed after a filament
eruption in the norrthwest quadrant very early in the day. The CME could
reach Earth on September 10.
[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 holes 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 poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to active on September 10-11 and September 13 due to CME effects. September 12 could see quiet conditions.
| 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 | ||||||||||
| 13806 | 2024.08.27 2024.08.28 |
10 | 16 | 8 | S08W81 | 0090 | CSO | DAO |
 |
 |
beta-gamma location: S11W77 area: 0130 |
| 13808 | 2024.08.29 2024.08.30 |
4 | S09W72 | 0060 | CAO |
 |
merged with AR 13806 |
||||
| 13812 | 2024.08.29 2024.09.02 |
3 | 2 | N14W52 | 0008 | AXX |
 |
 |
location: N14W55 | ||
| 13818 | 2024.08.30 2024.09.07 |
3 | 12 | 6 | S12W49 | 0020 | CRO | CRO |
 |
 |
|
| 13809 | 2024.08.30 | S21W72 | location: S22W71 | ||||||||
| 13810 | 2024.08.31 2024.08.31 |
N16W74 |
location: N17W72 |
||||||||
| 13811 | 2024.08.31 2024.08.31 |
9 | 35 | 18 | S10W36 | 0240 | DSO | DSI |
 |
 |
beta-gamma area: 0300 location: S11W34 |
| S10081 | 2024.08.31 | S19W46 | |||||||||
| 13813 | 2024.09.01 2024.09.02 |
10 | 40 | 21 | S22W11 | 0220 | ESI | ESI |
 |
 |
beta-gamma location: S23W14 area: 0280 |
| 13821 | 2024.09.01 2024.09.08 |
5 | 13 | 6 | N14W37 | 0030 | CSO | DRI |
 |
 |
area: 0060 |
| S10086 | 2024.09.02 | 2 | 1 | N09W22 | 0003 | AXX |
 |
 |
|||
| 13815 | 2024.09.02 2024.09.06 |
5 | 45 | 19 | S27E01 | 0170 | CSO | FKI |
 |
 |
location: S25W02 area: 0310 |
| S10089 | 2024.09.02 | S32W52 | |||||||||
| S10090 | 2024.09.03 | N22W58 | |||||||||
| 13814 | 2024.09.04 2024.09.04 |
10 | 23 | 13 | N15E24 | 0230 | DSO | DHC |
 |
 |
beta-gamma area: 0400 location: N15E26 |
| S10092 | 2024.09.04 | S02W53 | |||||||||
| S10093 | 2024.09.04 | S07E16 | |||||||||
| 13816 | 2024.09.05 2024.09.06 |
1 | 18 | 15 | S12W10 | 0005 | CRO | DAI |
 |
 |
location: S10W08 area: 0100 SWPC classification is impossible with just 1 spot |
| S10095 | 2024.09.05 | 7 | 2 | N21W23 | 0015 | BXO |
 |
 |
|||
| S10096 | 2024.09.05 | 11 | 3 | N16E13 | 0020 | BXO |
 |
 |
|||
| S10097 | 2024.09.05 | 12 | 4 | S17E27 | 0025 | BXO |
 |
 |
|||
| 13819 | 2024.09.07 | 8 | S30E06 | 0010 | CSI |
 |
SWPC location on Sept. 7: S12E41 The new location appears to be the trailing spots of AR 13815. The reasons for this misinterpretation and change of location are unknown |
||||
| S10098 | 2024.09.06 | N02W02 |
 |
||||||||
| S10099 | 2024.09.06 | S08E46 |
 |
||||||||
| 13817 | 2024.09.07 | S14E23 | It's uncertain what SWPC observed on Sept.7, there were no spots in that location | ||||||||
| S10101 | 2024.09.07 | 7 | 4 | N12E36 | 0020 | CRO |
 |
 |
|||
| S10102 | 2024.09.07 | S07E15 |
 |
||||||||
| 13820 | 2024.09.08 | 1 | S22W10 | 0020 | HSX | again it is unclear what SWPC has observed, the location is the same as for AR 13813 | |||||
| S10103 | 2024.09.08 | 4 | N20E34 | 0004 | BXO |
 |
|||||
| S10104 | 2024.09.08 | 4 | 3 | S12W13 | 0020 | CRO |
 |
||||
| Total spot count: | 66 | 252 | 125 | ||||||||
| Sunspot number: | 176 | 412 | 275 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 117 | 304 | 177 | (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): | 194 | 227 | 220 | ||||||||
| 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 |
| 2022.12 | 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 |
| 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 | 124.2 (+1.3) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 160.5 | 125.3 (+1.1) | 8.95 |
| 2023.07 | 176.4 | 182.2 | 160.0 | 124.6 (-0.7) | 8.15 |
| 2023.08 | 153.7 | 157.6 | 114.8 | 124.3 (-0.3) | 7.19 |
| 2023.09 | 154.4 | 156.0 | 134.2 | 124.0 (-0.3) | 14.26 |
| 2023.10 | 142.8 | 141.9 | 99.4 | 124.8 (+0.8) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 105.4 | 127.8 (+3.0) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 114.2 | 129.4 (+1.6) | 9.60 |
| 2024.01 | 164.6 | 159.3 | 126.0 | 131.1 (+1.7) | 5.46 |
| 2024.02 | 172.5 | 168.3 | 123.0 | 136.8 (+5.7) | 5.31 |
| 2024.03 | 154.4 | 152.9 | 103.7 | (143.3 projected, +6.5) | 11.03 |
| 2024.04 | 161.3 | 162.6 | 136.5 | (147.8 projected, +4.5) | 9.69 |
| 2024.05 | 187.7 | 191.9 | 171.7 | (152.6 projected, +4.8) | 23.56 (SC25 peak) |
| 2024.06 | 184.3 | 190.2 | 164.2 | (156.5 projected, +4.0) | 10.24 |
| 2024.07 | 196.6 |
203.0 | 196.5 | (158.3 projected, +1.8) | 7.13 |
| 2024.08 | 246.1 (cycle peak) |
252.2 | 215.5 (SC25 peak) | (158.7 projected, +0.4) | 15.8 |
| 2024.09 | 236.2 (1) | 45.0 (2A) / 168.8 (2B) / 209.8 (2C) | (160.8 projected, +2.1) | (7.6) | |
| 2024.10 | (162.7 projected, +1.9) | ||||
| 2024.11 | (160.7 projected, -2.0) | ||||
| 2024.12 | (156.4 projected, -4.3) | ||||
| 2025.01 | (150.3 projected, -6.1) | ||||
| 2025.02 | (143.0 projected, -7.3) | ||||
| 2025.03 | (136.2 projected, -6.8) | ||||
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
Sunspot counts in August 2024 were much higher than during any previous solar cycle 25 month. In comparison only 3 months during solar cycle 23 had higher SSN. Sunspot counts in early September are still high, although lower than in the beginning of August. With at least 5 consecutive months of high sunspot counts the projected peak for the smoothed ISN (365 days smoothing) has increased significantly to above 160 and could easily surpass 170 if the current activity lasts through October. The month of the peak is likely to occur sometime between July and November 2024.
--------------------------------------------------------------------------------------
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.
