Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 22, 2023 at 08:35 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 (October 1, 2023) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (October 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 (October 1, 2023) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (October 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 to minor storm on October 21 under the influence of CME effects. Solar wind speed at SOHO ranged between 309 and 369 km/sec. The high latitude magnetometer at Andenes recorded unsettled to minor storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 122.6 - decreasing 51.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 155.60. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 22 (STAR Ap - based on the mean of three hour interval ap indices: 22.0). Three hour interval K indices: 45532311 (planetary), 33553311 (Boulder), 55533443 (Andenes).

The background x-ray flux is at the class B4 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 154) and in 9 active regions using 1K resolution (SN:116) SDO/HMI images.

Region 13465 [N10W61] decayed slowly and quietly.
Region 13467 [N14W25] decayed slowly and was mostly quiet.
Region 13468 [S10E03] was quiet and stable.
Region 13469 [N27W49] decayed slowly and quietly.
New region 13470 [N24E16] rotated into view on October 16 and was numbered 5 days later by SWPC as the region developed slowly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9063 [N06W07] was quiet and stable.
New region S9075 [S25W14] emerged with tiny spots before noon.
New region S9076 [S10W44] emerged with a tiny spot.
New region S9077 [S13W22] emerged with a tiny spot.

AR 13464 produced a C1.5 flare at 12:10 UT while near the southwest limb.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 00:30   13467 GOES16 LDE

Coronal mass ejections (CMEs)

October 19-21: No obviously Earth directed CMEs were observed.

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 northern hemisphere positive polarity coronal hole (CH1181) will likely become Earth facing on October 22.

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 to unsettled on October 22-25. On October 25-26 a weak disturbance related to CH1181 is possible.

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
13464 2023.10.09
2023.10.10
1     N03W90 0030 HSX     rotated out of view
13465 2023.10.10
2023.10.11
  4 1 N12W64 0010   BXO location: N10W61
S9054 2023.10.12       S00W49            
13467 2023.10.13
2023.10.14
2 4 1 N14W26 0010 AXX BXO

location: N14W25

13468 2023.10.15
2023.10.16
1 15 4 S10E01 0070 HSX CSO area: 0120

location: S10E03

S9063 2023.10.15   9 2 N06W07 0015   BXO  
S9064 2023.10.15       S18W41            
S9065 2023.10.15       N07W36            
13470 2023.10.16
2023.10.21
5 18 9 N24E16 0020 CRO DRO area: 0040
S9071 2023.10.17       N02W48            
13469 2023.10.18
2023.10.20
6 9 5 N27W51 0030 DRO DRO area: 0040

location: N27W49

S9073 2023.10.19       S27E04            
S9074 2023.10.20       S04E34          
S9075 2023.10.21   3 2 S25W14 0008   CRO    
S9076 2023.10.21   1 1 S10W44 0003   AXX    
S9077 2023.10.21   1 1 S13W22 0002   AXX    
Total spot count: 15 64 26  
Sunspot number: 65 154 116  (total spot count + 10 * number of spotted regions)
Weighted SN: 31 78 40  (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): 72 85 93  

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 80.5 101.1 (+2.2) 9.33
2022.12 147.9 143.4 112.8 106.7 (+5.6) 10.99
2023.01 182.4 176.6 144.4 113.4 (+6.7) 8.73
2023.02 167.2 163.2 111.3 117.9 (+3.5) 14.48
(current
SC25 peak)
2023.03 157.2 155.6 123.3 121.2 (+3.3) 14.42
2023.04 145.4 146.4 97.6 (126.6 projected, +5.4) 13.40
2023.05 155.6 159.2 137.4 (132.2 projected, +5.6) 10.67
2023.06 161.7 166.8 160.5 (135.4 projected, +3.2) 8.95
2023.07  176.4 182.2 159.1 (135.8 projected, +0.4) 8.15
2023.08  153.7 157.6 114.9 (137.6 projected, +1.8) 7.19
2023.09  154.4 156.0 133.6 (141.0 projected, +3.4) 14.26
2023.10  149.2 (1)   76.7 (2A) / 113.2 (2B) / 138.4 (2C) (142.8 projected, +1.8) (7.2)
2023.11       (145.4 projected max SC25, +2.6)  
2023.12       (144.5 projected, -0.9)  
2024.01       (141.7 projected, -2.8)  
2024.02       (141.5 projected, -0.2)  
2024.03       (141.0 projected, -0.5)  
2024.04       (138.2 projected, -2.8)  

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

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.