The geomagnetic field was quiet to active on September 8 under the influence of weak CME effects. The high latitude magnetometer at Andenes recorded quiet to major storm conditions.
Solar flux density measured at 20h UT on 2.8 GHz was 100.4 - increasing 26.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 78.65). The Potsdam WDC planetary A index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 14.1). Three hour interval K indices: 42343221 (planetary), 33354321 (Boulder), 64234234 (Andenes).
The background x-ray flux is at the class B3 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 8 active regions using 2K resolution (SN: 208) and in 6 active regions using 1K resolution (SN: 127) SDO/HMI images.
Region 12863 [S16W53] decayed slowly and
quietly.
Region 12864 [N24W48] was quiet and stable.
Region 12866 [S18E08] displayed minor penumbral fragmentation and produced a
C1.2 flare at 10:26 and a C8.3 flare at 17:30 UT.
Region 12868 [S20W09] decayed slowly and was the source of a C1.1
flare at 03:14 and a C2.3 flare at 12:58 UT.
New region 12869 [S34E11] emerged on September 7 and developed
further on September 8 when it was numbered by SWPC.
Spotted regions not observed (or interpreted
differently) by SWPC:
S7057 [N28W21] reemerged with tiny spots.
New region S7068 [S31E70] emerged near the
southeast limb.
New region S7069 [N11E21] emerged with a tiny spot.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
| C2.3 | 12:58 | S20W03 | 12868 | GOES16 | |
| C8.3/1N | 17:30 | S16E12 | 12866 | GOES16 |
September 6-7: No obviously Earth directed CMEs
were observed in available LASCO imagery.
September 8: A CME was observed off the west limb early in the day
following a C2 flare late on September 7 in AR 12864. It is uncertain if the
CME has an Earth directed component.
[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 small northern hemisphere coronal hole (CH1029) will be Earth facing on September 9.
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 on September 9-11. On September 11 there is a chance of a weak CME impact and unsettled to active conditions if any parts of the September 8 CME were Earth directed.
| 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 red colored.
| 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 | ||||||||||
| S7057 | 2021.08.31 | 3 | N27W21 | ||||||||
| 12863 | 2021.09.01 2021.09.02 |
1 | 2 | 2 | S16W54 | 0080 | HSX | HSX |
 |
 |
|
| 12864 | 2021.09.02 2021.09.03 |
1 | 11 | 3 | N24W45 | 0110 | HSX | CAO |
 |
 |
location: N24W48 |
| 12865 | 2021.09.03 2021.09.04 |
N23W27 | |||||||||
| S7061 | 2021.09.03 | N23W58 | |||||||||
| S7062 | 2021.09.03 | N15W00 | |||||||||
| 12868 | 2021.09.03 2021.09.05 |
17 | 42 | 25 | S21W08 | 0300 | DHI | DSI |
 |
 |
area: 0260 location: S20W09 |
| 12866 | 2021.09.03 2021.09.04 |
15 | 48 | 25 | S18E07 | 0500 | DKC | DKC |
 |
 |
|
| 12869 | 2021.09.07 2021.09.08 |
3 | 18 | 11 | S35E12 | 0010 | BXO | DRI |
 |
 |
area: 0080 location: S34E11 |
| S7068 | 2021.09.08 | 3 | 1 | S31E70 | 0015 | HRX |
 |
||||
| S7069 | 2021.09.08 | 1 | N11E21 | 0001 | AXX |
 |
|||||
| Total spot count: | 37 | 128 | 67 | ||||||||
| Sunspot number: | 87 | 208 | 127 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 67 | 159 | 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): | 96 | 114 | 102 | ||||||||
| 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 (cycle peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (cycle 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 |
| 2020.03 | 70.2 | 69.5 | 1.5 | 3.0 (+0.3) | 5.63 |
| 2020.04 | 69.5 | 70.0 | 5.4 | 3.6 (+0.6) | 5.32 |
| 2020.05 | 69.0 | 70.6 | 0.2 | 5.6 (+2.0) | 3.80 |
| 2020.06 | 69.5 | 71.7 | 5.8 | 7.9 (+2.3) | 3.75 |
| 2020.07 | 69.5 | 71.8 | 6.3 | 9.0 (+1.1) | 4.28 |
| 2020.08 | 71.6 | 73.4 | 7.6 | 9.5 (+0.5) | 5.68 |
| 2020.09 | 70.7 | 71.4 | 0.7 | 10.5 (+1.0) | 8.59 |
| 2020.10 | 74.6 | 74.2 | 14.6 | 11.9 (+1.4) | 6.13 |
| 2020.11 | 89.9 | 88.0 | 34.5 | 13.6 (+1.7) | 4.77 |
| 2020.12 | 86.9 | 84.2 | 23.1 | 15.3 (+1.7) | 4.72 |
| 2021.01 | 76.0 | 73.6 | 10.4 | 17.3 (+2.0) | 4.39 |
| 2021.02 | 74.3 | 72.4 | 8.3 | 19.1 (+1.8) | 9.50 |
| 2021.03 | 76.0 | 75.2 | 17.3 | (21.4 projected, +2.3) | 10.17 |
| 2021.04 | 75.9 | 76.4 | 24.5 | (25.0 projected, +3.6) | 8.40 |
| 2021.05 | 75.3 | 77.1 | 21.2 | (27.7 projected, +2.7) | 6.50 |
| 2021.06 | 79.4 | 81.8 | 25.3 | (30.9 projected, +3.2) | 5.52 |
| 2021.07 | 81.0 | 83.6 | 34.4 | (35.5 projected, +4.6) | 5.51 |
| 2021.08 | 77.7 | 79.7 | 22.4 | (40.2 projected, +4.7) | 6.0 |
| 2021.09 | 91.8 (1) | 16.2 (2A) / 60.9 (2B) / 43.3 (2C) | (45.9 projected, +5.7) | (6.4) | |
| 2021.10 | (50.3 projected, +4.4) | ||||
| 2021.11 | (54.9 projected, +4.6) | ||||
| 2021.12 | (60.7 projected, +5.8) | ||||
| 2022.01 | (64.3 projected, +3.6) | ||||
| 2022.02 | (69.1 projected, +4.8) | ||||
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: 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.
