Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 14, 2024 at 05:20 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 6, 2024)
Solar cycle Solar cycles 23-25 (October 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (October 1, 2024) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (August 1, 2020) POES auroral activity level [October 2009 - December 2012]
  Comparison of cycles 21-25 (October 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (October 1, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (October 13, 2024) 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
Calculating the Strength of Solar Cycle 25 Using 365-day Smoothing

Recent activity

The geomagnetic field was at quiet levels on October 13. Solar wind speed at SOHO ranged between 413 and 543 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels. The above 10 MeV proton flux was at background levels at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 194.9 - increasing 25.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 179.65. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 179.65 on April 13, 2024). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.6). Three hour interval K indices: 10012121 (planetary), 111223** (Boulder), 10022232 (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 17 active regions using 2K resolution (SN: 352) and in 14 active regions using 1K resolution (SN: 225) SDO/HMI images.

AR 13848 [N15W75] decayed slowly as it approached the northwest limb. An M3.4 flare was recorded at 00:17 UT on October 14.
AR 13849 [S06W53] produced a few C flares and decayed slowly. C1 flares: C1.8 @ 20:15 UT
AR 13850 [S08W58] was quiet and stable.
AR 13852 [S11W11] was mostly quiet and stable. C1 flares: C1.6 @ 22:42 UT
AR 13853 [N20W08] was quiet and stable.
AR 13854 [S06W03] was mostly quiet and stable.
New AR 13855 [N16W34] emerged on October 12 and was numbered by SWPC the next day. C1 flares: C1.7 @ 16:48 UT
New AR 13856 [N09E32] rotated into view on October 10 and received its NOAA number 3 days later.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S10213 [S13E06] was quiet and stable.
S10220 [S12W50] was quiet and stable.
S10231 [N15E34] was quiet and stable.
New region S10233 [S15E73] rotated into view with small spots.
New region S10234 [S06E30] was observed with tiny spots in an old plage area.
New region S10235 [S07E83] rotated into view with a few spots.
New region S10236 [N02E24] emerged with a tiny spot.
New region S10237 [N33E37] emerged with tiny spots.
New region S10238 [S22E21] was observed with tiny spots in an old plage area.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment|
C2.4 01:12   13848 GOES16  
C2.5 01:42 southeast limb S10233 GOES16 simultaneous flare in AR 13852
C2.7 01:48   13848 GOES16  
C3.0 03:33   13849 GOES16  
C2.5 05:05   13852 GOES16  
C4.0 05:32   13852 GOES16  
C4.1 05:39   13852 GOES16  
C4.2 06:01   13856 GOES16  
C5.7 06:57 N18W63 13848 GOES16  
C3.3 07:34   13848 GOES16  
C2.2 08:29   13854 GOES16  
C2.6 09:29   13854 GOES16  
C2.0 12:22   13854 GOES16  
C2.8 15:16   13849 GOES16  
C2.6 16:23   13848 GOES16  
C2.7 17:31   13854 GOES16  
C2.1 18:52   13855 GOES16  
C2.0 23:33   13855 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 positive polarity northern hemisphere coronal hole (CH1246) was in an Earth facing position on October 12. Another positive polarity northern hemisphere coronal hole (CH1247) could rotate across the central meridian on October 14-16.

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 at mostly quiet levels on October 14-17. There is a chance of unsettled intervals on Oct.15 due to effects from CH1246. Effects from CH1247 could cause quiet to active levels on October 18-20.

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
13848 2024.10.01
2024.10.02
4 8 6 N13W79 0350 DHI DKO

area: 0800

location: N14W75

13849 2024.10.03
2024.10.04
5 26 13 S06W56 0240 DAI CSI beta-gamma

location: S06W53

area: 0320

13850 2024.10.06
2024.10.06
1 1 1 S08W57 0090 HSX HSX

area: 0130

13852 2024.10.06 8 43 19 S10W15 0300 DKI DKI  

beta-gamma-delta

location: S11W11

area: 0630

13853 2024.10.08
2024.10.10
  9 5 N22W05 0015   BXO

location: N20W08

S10212 2024.10.08       N29W43            
S10213 2024.10.08   6 1 S13E06 0010   BXO  
13854 2024.10.08
2024.10.10
15 39 22 S04W05 0260 EKI EKI beta-gamma

location: S06W03

area: 0600

S10215 2024.10.08       N20W38            
S10216 2024.10.09       S15E19            
S10217 2024.10.09       S43W35            
S10218 2024.10.09       S23W40            
S10220 2024.10.10   4 1 S12W50 0015   CRO  
S10222 2024.10.10       N28W46            
13856 2024.10.10
2024.10.13
1 5 3 N09E37 0010 BXO CRO location: N09E32
S10225 2024.10.11       S09W28          
S10227 2024.10.11       N12W22            
S10228 2024.10.11       N47W06            
13855 2024.10.12
2024.10.13
4 12 7 N14W33 0020 CSO DRI location: N16W34

area: 0050

S10230 2024.10.12       N10E42          
S10231 2024.10.12   6   N15E34 0008   BXO  
S10232 2024.10.12       N27W01          
S10233 2024.10.13   3 2 S15E73 0060   CAO    
S10234 2024.10.13   7 2 S06E30 0015   BXO    
S10235 2024.10.13   3 2 S07E83 0150   DAO    
S10236 2024.10.13   1   N02E24 0001   AXX    
S10237 2024.10.13   4   N33E37 0006   BXO    
S10238 2024.10.13   5 1 S22E21 0010   BXO    
Total spot count: 38 182 85  
Sunspot number: 108 352 225  (total spot count + 10 * number of spotted regions)
Weighted SN: 83 241 144  (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): 119 194 180  

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
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
2023.03 157.2 155.6 123.3 121.1 (+3.3) 14.42
2023.04 145.4 146.4 97.6 122.9 (+1.8) 13.40
2023.05 155.6 159.2 137.4 124.2 (+1.3) 10.67
2023.06 161.7 166.8 160.5 125.3 (+1.1) 8.95
2023.07  176.4 182.2 160.0 124.6 (-0.7) 8.15
2023.08  153.7 157.6 114.8 124.3 (-0.3) 7.19
2023.09  154.4 156.0 134.2 124.0 (-0.3) 14.26
2023.10  142.8 141.9 99.4 124.8 (+0.8) 8.16
2023.11 153.5 150.2 105.4 127.8 (+3.0) 12.20
2023.12 151.1 146.4 114.2 129.4 (+1.6) 9.60
2024.01 164.6 159.3 126.0 131.1 (+1.7) 5.46
2024.02 172.5 168.3 123.0 136.8 (+5.7) 5.31
2024.03 154.4 152.9 103.7 141.3 (+4.5) 11.03
2024.04 161.3 162.6 136.5 (145.3 projected, +4.0) 9.69
2024.05 187.7 191.9 171.7 (151.6 projected, +6.3) 23.56
(SC25 peak)
2024.06 184.3 190.2 164.2 (155.5 projected, +3.9) 10.24
2024.07 196.6
 
203.0 196.5  (158.4 projected, +2.9) 7.13
2024.08  246.1
(cycle peak)
252.2 215.5  (SC25 peak) (160.4 projected, +2.0) 15.96
2024.09 195.7 197.8 141.4 (163.1 projected, +2.7) 15.36
2024.10 245.5 (1)   66.4 (2A) / 158.4 (2B) / 200.4 (2C) (165.4 projected, +2.3) (25.3)
2024.11       (163.7 projected, -1.7)  
2024.12       (160.7 projected, -3.0)  
2025.01       (156.3 projected, -4.4)  
2025.02       (149.6 projected, -6.7)  
2025.03       (144.8 projected, -4.8)  
2025.04       (141.6 projected, -3.2)  

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 October 6, 2024

September 2024 saw a significant decrease in sunspot numbers compared to the previous month, however, activity was still fairly high. The average solar flux for the month ranks as number 3 of all months during SC25. Taking into account that we started seeing high sunspot numbers April 14, 2024, the most likely candidate for solar maximum would be at or just after October 14, 2024. Assuming that the average sunspot number from now until April 14, 2025 becomes 150, we would be looking at a 365 days smoothed sunspot maximum of 164.5 centered on October 14. Should the average sunspot number for that period become 160 we would get a peak near 169.7.

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

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.