Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 12, 2023 at 15:20 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 very quiet on October 11. Solar wind speed at SOHO ranged between 300 and 350 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels.

Solar flux density measured at 20h UT on 2.8 GHz was 158.0 - increasing 12.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 155.09. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.4). Three hour interval K indices: 00111001 (planetary), 01112211 (Boulder), 00011103 (Andenes).

The background x-ray flux is at the class C2 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 261) and in 12 active regions using 1K resolution (SN: 185) SDO/HMI images.

Region 13451 [N16W82] rotated partly out of view and produced several C flares. C1 flares: C1.7 @ 05:02, C1.9 @ 07:06, C1.7 @ 07:27 UT
Region 13454 [S10W70] was mostly quiet and stable.
Region 13455 [N27W51] reemerged with tiny spots.
Region 13460 [S11W16] decayed slowly and was mostly quiet. C1 flares: C1.7 @ 07:37 UT
Region 13461 [N14W01] developed slowly and quietly.
Region 13462 [N18E26] developed slowly and quietly.
Region 13463 [S18E36] developed slowly and quietly.
Region 13464 [N04E49] developed slowly and was mostly quiet. C1 flares: C1.9 @ 12:27 UT.
New region 13465 [N10E70] rotated into view on October 10 and was numbered the next day by SWPC. C1 flares: C1.5 @ 10:39 UT
New region 13466 [N08E07] was first observed with spots on October 8 and developed on October 11 when the region was numbered by SWPC.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9036 [N27W15] was quiet and stable.
S9049 [S05W01] was quiet and stable.
S9050 [S15W03] was quiet and stable.
S9051 [S24E12] was quiet and stable.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.8 01:01   13464 GOES16  
C2.8 01:12   13460 GOES16  
C7.2 09:37 N17W78 13451 GOES16  
C4.9 14:40 N13W85 13451 GOES16  
C2.0 16:26   13454 GOES16  
C3.5 19:54   13451 GOES16  
C2.0 20:53   13451 GOES16  
C6.6 22:12   13451 GOES16  
C3.1 22:23   13451 GOES16  
C3.0 23:10   13454 GOES16  

Coronal mass ejections (CMEs)

October 8-10: 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 trans equatorial coronal hole (CH1178) was Earth facing on October 8-9. A small southern hemisphere positive polarity coronal hole (CH1179) will likely rotate 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 very good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on October 12-14.

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
13451 2023.09.29
2023.09.30
3 4 3 N16W86 0270 EKI HKX

location: N16W82

13452 2023.09.29
2023.10.01
1     N09W94 0005 AXX    

 

13454 2023.09.30
2023.10.01
1 1 1 S11W71 0050 CSO HAX

location: S10W70

13455 2023.10.01
2023.10.02
  2 1 N27W63 0007   AXX   location: N26W51
13457 2023.10.03
2023.10.04
      S11W31         location: S13W27
13459 2023.10.05       N07W12            
S9025 2023.10.05       S18W54            
13461 2023.10.05
2023.10.08
3 8 5 N11W02 0020 CRO DRO location: N14W01

area: 0030

S9027 2023.10.05       N20W40            
S9028 2023.10.05       N10W45            
13460 2023.10.05
2023.10.07
11 24 14 S10W20 0110 DAI EAO beta-gamma

area: 0370

location: S11W16

S9031 2023.10.06       N02E10            
13462 2023.10.06
2023.10.08
8 19 9 N23E22 0070 DAO DRO location: N18E26
S9036 2023.10.07   4   N27W15 0006   BXO  
13463 2023.10.08
2023.10.09
7 20 12 S17E33 0050 DAI DRI location: S18E36

area: 0110

S9039 2023.10.08       N12W46            
13466 2023.10.08
2023.10.11
6 13 7 N09E05 0030 CRO DRO area: 0080
S9043 2023.10.09       N14W53            
13464 2023.10.09
2023.10.10
6 14 8 N04E50 0080 CAO DAI beta-gamma

area: 0130

location: N04E49

13465 2023.10.10
2023.10.11
3 5 3 N10E69 0120 DSO HKX area: 0300
S9049 2023.10.10   3 1 S05W01 0006   AXX  
S9050 2023.10.10   2   S15W03 0006   AXX  
S9051 2023.10.10   2 1 S24E12 0005   AXX  
Total spot count: 49 121 65  
Sunspot number: 149 261 185  (total spot count + 10 * number of spotted regions)
Weighted SN: 95 168 112  (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): 165 144 148  

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  158.3 (1)   51.4 (2A) / 144.7 (2B) / 149.5 (2C) (142.8 projected, +1.8) (7.0)
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.