The geomagnetic field was at unsettled to major storm levels on September 13 under the influence of CME effects. Solar wind speed at SOHO ranged between 386 and 599 km/sec. The high latitude magnetometer at Andenes recorded unsettled to major storm levels. The above 10 MeV proton flux was at 0.6 pfu at the end of the day.
Solar flux density measured at 20h UT on 2.8 GHz was 185.8 - decreasing 43.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 175.77. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 175.77 on March 15, 2024). The Potsdam WDC planetary A index was 35 (STAR Ap - based on the mean of three hour interval ap indices: 35.0). Three hour interval K indices: 54433446 (planetary), 54444334 (Boulder), 65543456 (Andenes).
The background x-ray flux is at the class C3 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 298) and in 12 active regions using 1K resolution (SN: 205) SDO/HMI images.
AR 13813 [S23W79] decayed further and was quiet.
AR 13814 [N15W40] decayed further and lost the
magnetic delta.
AR 13815 [S26W69] was quiet and stable
AR 13816 [S09W77] decayed slowly and quietly.
AR 13822 [N14W31] decayed slowly losing all mature penumbra. The
region has many small spots.
AR 13824 [S04E00] decayed slowly and was mostly quiet.
New AR 13825 [S17E63] rotated into view on September 12 and was
numbered the next day. The spot group is compact and complex and further M
class flaring is likely.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S10096 [N16W49] was quiet and stable.
S10107 [S12W34] decayed slowly and quietly.
New region S10113 [S11W69] emerged to the
southeast of AR 13816.
New region S10114 [N13E07] emerged with tiny spots before noon, then
decayed slowly.
New region S10115 [S12E43] was observed with tiny spots in an old
plage area.
New region S10116 [N20W63] emerged with tiny spots.
New region S10117 [N19E29] was observed with tiny spots in an old
plage area.
Minor update added at 15:35 UT: AR 13825 produced a major X4.5 flare at 15:29 UT. Another update will be added if an Earth directed CME was associated with this flare.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| M1.5 | 00:56 | behind southwest limb | 13811 | GOES16 | |
| M1.6 | 01:37 | behind southwest limb | 13811 | GOES16 | |
| M1.4 | 01:46 | behind southwest limb | 13811 | GOES16 | |
| M1.3 | 02:03 | 13825 | GOES16 | ||
| M1.3 | 02:39 | behind southwest limb | 13811 | GOES16 | |
| M1.4 | 03:25 | 13825 | GOES16 | ||
| M1.5 | 03:55 | behind southwest limb | 13811 | GOES16 | |
| M2.1 | 04:34 | 13815 | GOES18 | ||
| M2.1 | 04:39 | 13825 | GOES18 | attributed to AR 13815 by SWPC, that flare peaked earlier | |
| M2.3 | 05:00 | behind southwest limb | 13811 | GOES18 | |
| M1.8 | 05:37 | behind southwest limb | 13811 | GOES18 | |
| M5.4 | 06:56 | behind southwest limb | 13811 | GOES16 | |
| M5.2 | 07:08 | behind southwest limb | 13811 | GOES16 | |
| M2.8 | 08:32 | behind southwest limb | 13811 | GOES16 | |
| M2.9 | 08:37 | N13W29 | 13814 | GOES16 | CME |
| M1.4 | 09:13 | 13814 | GOES16 | ||
| C9.6 | 10:36 | behind southwest limb | 13811 | GOES16 | |
| C6.6 | 11:52 | behind southwest limb | 13811 | GOES16 | |
| C9.6 | 12:33 | 13823 | GOES16 | ||
| C6.0 | 14:34 | behind southwest limb | 13811 | GOES16 | |
| M1.2 | 15:08 | behind southwest limb | 13811 | GOES16 | initially attributed to AR 13825 by SWPC, however, that flare peaked later |
| M1.2 | 15:18 | S15E67 | 13825 | GOES16 | |
| C7.5 | 16:02 | behind southwest limb | 13811 | GOES16 | |
| C5.6 | 16:45 | 13825 | GOES16 | ||
| C5.4 | 17:12 | 13813 | GOES16 | ||
| C6.4 | 17:32 | 13825 | GOES16 | ||
| C6.2 | 17:43 | behind southwest limb | 13811 | GOES16 | |
| M1.4 | 17:56 | S14E63 | 13825 | GOES16 | |
| C9.4 | 19:03 | behind southwest limb | 13811 | GOES16 | initially attributed to smaller, simultaneous flare in AR 13825 by SWPC |
| C7.7 | 20:08 | behind southwest limb | 13811 | GOES16 | |
| C8.3 | 20:21 | 13825 | GOES16 | ||
| C8.2 | 20:27 | behind southwest limb | 13811 | GOES16 | |
| M1.1 | 20:49 | S14E64 | 13825 | GOES16 | |
| C4.8 | 21:29 | 13825 | GOES16 | ||
| C3.1 | 22:23 | 13823 | GOES16 | ||
| C6.2 | 23:32 | behind southwest limb | 13811 | GOES16 | attributed to AR 13813 by SWPC, however, the flare was behind the limb |
| C5.4 | 23:47 | behind southwest limb | 13811 | GOES16 |
September 13: A partial halo CME was observed after the M2.9 flare in
AR 13814 peaking at 08:37 UT. This CME could reach Earth on September 16.
September 11-12: No obviously Earth directed CMEs 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 southern hemisphere positive polarity coronal hole (CH1241) will rotate into an Earth facing position on September 12-13. CH1241 may be too far to the south to cause a geomagnetic disturbance.
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 14-15 due to CME and coronal hole effects. On September 16 quiet to major storm disturbance levels are possible should the September 13 CME reach Earth.
| 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 | ||||||||||
| 13813 | 2024.09.01 2024.09.02 |
1 | 1 | S24W80 | 0030 | HAX | AXX |
 |
 |
location: S23W79 |
|
| 13815 | 2024.09.02 2024.09.06 |
1 | 3 | 2 | S26W69 | 0040 | HSX | CSO |
 |
 |
area: 0190 |
| 13814 | 2024.09.04 2024.09.04 |
6 | 15 | 6 | N16W43 | 0110 | CSO | CHO |
 |
 |
beta-gamma area: 0310 location: N15W40 |
| S10093 | 2024.09.04 | S07W49 | |||||||||
| 13816 | 2024.09.05 2024.09.06 |
1 | 4 | 2 | S08W76 | 0010 | AXX | AXX |
 |
 |
location: S09W77 |
| S10096 | 2024.09.05 | 2 | 1 | N16W49 | 0008 | AXX |
 |
 |
|||
| S10097 | 2024.09.05 | 4 | S12W34 | 0005 | BXO |
 |
|||||
| 13819 | 2024.09.07 | S27W64 | within the boundaries of AR 13815 | ||||||||
| S10098 | 2024.09.06 | N01W55 | |||||||||
| S10099 | 2024.09.06 | S08W19 | |||||||||
| 13817 | 2024.09.07 | S14W47 | It's uncertain what SWPC observed on Sept.7 when they numbered this AR, there were no spots in the location provided for that day | ||||||||
| 13822 | 2024.09.07 2024.09.09 |
13 | 38 | 21 | N14W31 | 0140 | DAI | DRI |
 |
 |
area: 0070 |
| S10102 | 2024.09.07 | S07W50 | |||||||||
| 13820 | 2024.09.08 | S21W76 |
after several days of data that could not be traced to actual spots,
SWPC moved AR 13820 to the positive polarity section of AR 13813 on
Sept.12
SWPC location on Sept. 10 was S18W38 |
||||||||
| S10103 | 2024.09.08 | N24W30 | |||||||||
| 13824 | 2024.09.10 2024.09.11 |
13 | 38 | 23 | S05E01 | 0110 | DSI | ESI |
 |
 |
location: S04E00 area: 0240 |
| S10107 | 2024.09.11 | S18W20 |
 |
||||||||
| 13825 | 2024.09.12 2024.09.13 |
6 | 33 | 22 | S18E63 | 0240 | DAC | EAC |
 |
 |
beta-gamma area: 0430 location: S17E63 |
| S10109 | 2024.09.12 | S14W11 |
 |
||||||||
| S10110 | 2024.09.12 | N13W04 |
 |
||||||||
| S10111 | 2024.09.12 | S12W50 |
 |
||||||||
| S10113 | 2024.09.13 | 3 | 2 | S11W69 | 0012 | DRO |
 |
||||
| S10114 | 2024.09.13 | 1 | 1 | N13E07 | 0003 | AXX |
 |
||||
| S10115 | 2024.09.13 | 6 | 1 | S12E43 | 0010 | AXX |
 |
||||
| S10116 | 2024.09.13 | 2 | 1 | N20W63 | 0008 | CRO |
 |
||||
| S10117 | 2024.09.13 | 8 | 3 | N19E29 | 0015 | AXX |
 |
||||
| Total spot count: | 41 | 158 | 85 | ||||||||
| Sunspot number: | 111 | 298 | 205 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 71 | 192 | 119 | (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): | 122 | 164 | 164 | ||||||||
| 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) | 15.96 |
| 2024.09 | 223.4 (1) | 72.0 (2A) / 166.2 (2B) / 201.1 (2C) [ISN average: 166] |
(160.8 projected, +2.1) | (14.6) | |
| 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.
