ESolar Terrestrial Activity Report

Activity chart

Last major update issued on October 31, 2023 at 07:50 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 active on October 30 under the influence of a high speed stream from CH1182. Solar wind speed at SOHO ranged between 505 and 622 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 139.7 - decreasing 14.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 155.75. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.0). Three hour interval K indices: 43133122 (planetary), 31044322 (Boulder), 54224233 (Andenes).

The background x-ray flux is at the class B8 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 202) and in 7 active regions using 1K resolution (SN: 116) SDO/HMI images.

Region 13472 [N19W12] was mostly quiet and stable. C1 flares: C1.1 @ 08:09, C1.0 @ 17:59, C1.0  @ 20:17 UT
Region 13473 [N17E22] was mostly quiet and stable.
Region 13474 [S18W01] developed quickly and has several large spots. A major flare is possible. C1 flares: C1.4 @ 03:49, C1.0 @ 08:01, C1.0 @ 09:58, C1.1 @ 19:36, C1.0 @ 20:58, C1.2 @ 22:01, C1.9 @ 23:15 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9082 [N20W24] was quiet and stable.
S9097 [S14E05] reemerged with a tiny spot.
S9102 [S16E24] was quiet and stable.
New region S9106 [N10E36] emerged with tiny spots.
New region S9107 [S21E46] emerged with tiny spots.
New region S9108 [S15E09] was observed with tiny spots in an old plage area.

AR 13471 at the southwest limb was the source of a C1.1 flare at 08:35 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment

Coronal mass ejections (CMEs)

October 28-30: 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 large and well defined positive polarity trans equatorial coronal hole (CH1182) rotated across the central meridian on October 27-28.

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 to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on October 31 due to effects from CH1182. Quiet conditions are likely on November 1-2.

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
13471 2023.10.22
2023.10.22
      S23W85          

location: S23W82

S9082 2023.10.22   7 3 N20W24 0015   AXX  
S9085 2023.10.23       N10W41            
S9087 2023.10.25       N19E02            
13472 2023.10.25
2023.10.26
8 23 9 N21W12 0040 DSO DRI location: N19W12

area: 0080

S9089 2023.10.25       N10E08          
13473 2023.10.25
2023.10.26
9 31 13 N16E20 0050 DSO DAO area: 0090

location: N17E22

S9091 2023.10.25       S16W50            
13475 2023.10.25
2023.10.28
      N13W80           location: N13W76
13474 2023.10.26
2023.10.27
15 36 17 S18W02 0130 DAI DKO location: S18W01

area: 0610

S9095 2023.10.26       N17W44            
S9097 2023.10.27   1   S14E05 0002   AXX    
S9098 2023.10.27       S17W14            
S9099 2023.10.28       S28W50            
S9101 2023.10.28       S35W36          
S9102 2023.10.28   4 2 S16E24 0012   BXO  
S9103 2023.10.28       S23W02          
S9104 2023.10.28       S19W37            
S9106 2023.10.30   4 1 N10E36 0009   BXO    
S9107 2023.10.30   2 1 S21E46 0006   BXO    
S9108 2023.10.30   4   S15E09 0008   BXO    
Total spot count: 32 112 46  
Sunspot number: 62 202 116  (total spot count + 10 * number of spotted regions)
Weighted SN: 47 130 64  (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): 68 111 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  142.6 (1)   91.2 (2A) / 94.2 (2B) / 116.0 (2C) (142.8 projected, +1.8) (8.3)
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.

--------------------------------------------------------------------------------------

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.