Solar Terrestrial Activity Report

Activity chart

Last major update issued on November 1, 2023 at 07:25 UT.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data since 2003.01 (October 8, 2023)
Solar cycle Solar cycles 23-25 (November 1, 2023) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (November 1, 2023) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (July 1, 2020) POES auroral activity level [October 2009 - December 2012]
  Comparison of cycles 21-25 (November 1, 2023) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (November 1, 2023) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (July 10, 2023) Cycle 25 spots (final update December 25, 2019)
  Solar cycles 24-25 transition using 365d smoothing Research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing

Recent activity

The geomagnetic field was quiet on October 31. Solar wind speed at SOHO ranged between 441 and 535 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels.

Solar flux density measured at 20h UT on 2.8 GHz was 147.3 - decreasing 7.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 155.80. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.1). Three hour interval K indices: 22222112 (planetary), 22233222 (Boulder), 43233234 (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 10 active regions using 2K resolution (SN: 213) and in 10 active regions using 1K resolution (SN: 168) SDO/HMI images.

Region 13472 [N20W25] developed slowly and was mostly quiet. C1 flares: C1.5 @ 13:07 UT
Region 13473 [N17E08] produced a few flares early in the day and decayed slowly.
Region 13474 [S17W13] displayed no significant changes. There is still a patch of negative polarity flux at the southeastern edge of the trailing penumbra. An M flare is possible. C1 flares: C1.8 @ 01:13, C1.0 @ 07:15, C1.6 @ 16:33. C1.3 @ 17:55 UT
New region 13476 [S14E08] emerged on October 28 and developed slowly on October 30 when it was numbered by SWPC. C1 flares: C1.4 @ 19:26 UT
New region 13477 [S14E79] rotated into view with a large, mature spot. C1 flares: C1.3 @ 15:06 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9082 [N21W35] was quiet and stable.
S9089 [N10W04] reemerged with tiny spots.
S9107 [S23E32] decayed slowly and quietly.
New region S9109 [N21E37] emerged with tiny spots.
New region S9110 [N12E84] rotated into view with a small spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C5.7 00:23   13473 GOES16  
C2.2 02:29   13474 GOES16  
C2.1 07:50   13473 GOES16  
C3.9 20:24   13477 GOES16  
C3.7 20:39 behind SE limb at approx. S10   GOES16 LDE, began at 19:49, ended at 20:58 UT
C5.0 21:58   13474 GOES16 simultaneous flare behind SE limb

Coronal mass ejections (CMEs)

October 29-30: No obviously Earth directed CMEs were observed.
October 31: A CME was observed starting at 22:12 UT in LASCO C2 imagery after a filament eruption in the central southern hemisphere. The core of the CME was observed off the south pole, weak extensions were seen off the southwest limb. Analysis was somewhat complicated due to a CME off the east limb (from a source just behind the southeast limb) that started at 21:12 UT in LASCO imagery. None of the CMEs are expected to reach Earth.

Coronal holes

[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 large and well defined negative polarity trans equatorial coronal hole (CH1183) will likely become Earth facing on November 4-5.

Propagation

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.

Forecast

The geomagnetic field is expected to be quiet on November 1-3.

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.

Active solar regions


(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
S9082 2023.10.22   6 3 N21W35 0012   BXO  
S9085 2023.10.23       N10W54            
S9087 2023.10.25       N19W11            
13472 2023.10.25
2023.10.26
20 27 15 N20W25 0030 DRO DRI

beta-gamma

area: 0100

S9089 2023.10.25   12 4 N10W05 0020   AXX    
13473 2023.10.25
2023.10.26
12 21 12 N16E09 0030 DRO DRO area: 0060

location: N16E09

13474 2023.10.26
2023.10.27
30 34 25 S18W15 0460 DKI DKI beta-gamma

location: S17W13

area: 0570

S9095 2023.10.26       N17W44            
S9097 2023.10.27       S14W08          
S9098 2023.10.27       S17W27            
S9101 2023.10.28       S35W49            
13476 2023.10.28
2023.10.31
3 5 3 S15E09 0030 CRO CRO location: S14E08
S9103 2023.10.28       S23W15            
S9106 2023.10.30       N10E23          
S9107 2023.10.30   1 1 S23E32 0002   AXX  
S9108 2023.10.30       S15W04          
S9109 2023.10.31   5 3 N21E37 0010   BXO    
S9110 2023.10.31   1 1 N12E84 0020   HRX    
13477 2023.10.31 1 1 1 S12E80 0120 HSX HHX   area: 0350
Total spot count: 66 113 68  
Sunspot number: 116 213 168  (total spot count + 10 * number of spotted regions)
Weighted SN: 90 145 100  (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): 128 117 134  

Monthly solar cycle data

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
2022.03 117.0 115.8 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 92.6 (+5.9) 10.92
2022.09 135.1 136.5 96.0 96.5 (+3.9) 12.18
2022.10 133.5 132.7 95.5 98.9 (+2.4) 11.16
2022.11 123.4 120.7 80.5 101.2 (+2.3) 9.33
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
(current
SC25 peak)
2023.03 157.2 155.6 123.3 121.0 (+3.2) 14.42
2023.04 145.4 146.4 97.6 122.7 (+1.7) 13.40
2023.05 155.6 159.2 137.4 (124.7 projected, +2.0) 10.67
2023.06 161.7 166.8 160.5 (127.9 projected, +3.2) 8.95
2023.07  176.4 182.2 159.1 (128.3 projected, +0.4) 8.15
2023.08  153.7 157.6 114.8 (130.1 projected, +1.8) 7.19
2023.09  154.4 156.0 133.6 (133.5 projected, +3.4) 14.26
2023.10  142.8 141.9 99.4 (135.2 projected, +1.7) 8.3
2023.11  (1)   (2A/2B) / 115.7 (2C) (137.8 projected max SC25, +2.6) ()
2023.12       (137.1 projected, -0.7)  
2024.01       (134.4 projected, -2.7)  
2024.02       (134.2 projected, -0.2)  
2024.03       (133.7 projected, -0.5)  
2024.04       (134.5 projected, +0.8)  
2024.05       (135.8 projected, +1.3)  

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

Solar cycles 24-25

Smoothed SF and sunspot numbers

Update on the progress of solar cycle 25 as of August 20, 2023

Looking back 6 months, the 365d smoothed values for solar flux and all sunspot numbers with the exception of NOAA's, are all above their solar cycle 24 peak. The first peak of solar cycle 25 is forecast to be between July 7 and 10, 2023 (solar flux on July 7, ISN and STAR 1K and 2K all have that peak on July 9, while NOAA peaks on July 10). This is unlikely to be the final peak of SC25, however, there is a small probability that it is the actual sunspot and solar flux maximum.

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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.