Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 15, 2023 at 07:30 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 unsettled on October 14. Solar wind speed at SOHO ranged between 486 and 569 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 148.2 - increasing 3.6 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 155.26. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.8). Three hour interval K indices: 21121131 (planetary), 11132231 (Boulder), 22111043 (Andenes).

The background x-ray flux is at the class B6 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 200) and in 9 active regions using 1K resolution (SN: 148) SDO/HMI images.

Region 13460 [S11W59] decayed slowly producing a C9 flare early in the day.
Region 13461 [N11W45] was quiet and stable.
Region 13462 [N19W13] decayed slowly and quietly.
Region 13463 [S18W02] was quiet and stable.
Region 13464 [N05E07] was mostly quiet and stable. C1 flares: C1.0 @ 23:38 UT
Region 13465 [N10E30] gained a few spots and was quiet.
Region 13466 [N08W36] decayed slowly and quietly,
New region 13467 [N12E65] rotated into view on October 13. Further C class flaring is possible although no spots have mature penumbra. C1 flares: C1.0 @ 13:06 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9053 [N18E06] was quiet and stable.
New region S9059 [S20W16] emerged with tiny spots.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C9.9 05:15 S11W44 13460 GOES18  
C3.4 16:33   13467 GOES16  

Coronal mass ejections (CMEs)

October 12-14: 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 small southern hemisphere positive polarity coronal hole (CH1179) rotated across the central meridian on October 12-13.

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 to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on October 15. Quiet to unsettled is likely on October 16 due to weak effects from CH1179 with quiet conditions returning on October 17-18.

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
13457 2023.10.03
2023.10.04
      S11W73           location: S13W66
13459 2023.10.05       N07W54            
13461 2023.10.05
2023.10.08
  6 2 N13W44 0010   AXX location: N11W45
13460 2023.10.05
2023.10.07
5 11 7 S10W57 0090 DAO EAO

area: 0170

S9031 2023.10.06       N02W29            
13462 2023.10.06
2023.10.08
1 9 3 N20W13 0010 AXX BXO location: N19W13
S9036 2023.10.07       N27W54            
13463 2023.10.08
2023.10.09
5 20 10 S17W05 0020 CRO DRI location: S18W02
13466 2023.10.08
2023.10.11
6 16 6 N09W36 0030 CAO CRI area: 0040

location: N08W35

13464 2023.10.09
2023.10.10
5 12 7 N04E09 0080 CAO DAO

area: 0190

location: N05E07

13465 2023.10.10
2023.10.11
3 11 5 N10E30 0220 HSX DKO area: 0320
S9049 2023.10.10       S05W40            
S9050 2023.10.10       S13W40            
S9051 2023.10.10       S23W27            
S9052 2023.10.12       S25E03            
S9053 2023.10.12   4 1 N18E06 0010   BXO  
S9054 2023.10.12       S00E29            
S9055 2023.10.12       S14W47            
S9056 2023.10.12       N18W31            
13467 2023.10.13
2023.10.14
5 9 6 N12E66 0040 CAO ERO  
S9059 2023.10.14   2 1 S20W16 0007   BXO    
Total spot count: 30 100 48  
Sunspot number: 100 200 148  (total spot count + 10 * number of spotted regions)
Weighted SN: 58 129 77  (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): 110 110 118  

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 96.4 (126.6 projected, +5.4) 13.40
2023.05 155.6 159.2 137.9 (132.2 projected, +5.6) 10.67
2023.06 161.7 166.8 163.4 (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  156.8 (1)   61.6 (2A) / 136.4 (2B) / 148.7 (2C) (142.8 projected, +1.8) (6.9)
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.