Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 6, 2023 at 07:15 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 (August 5, 2023)
Solar cycle Solar cycles 23-25 (August 1, 2023) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (August 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 (August 1, 2023) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (August 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 major storm on August 5 due to CME effects. Solar wind speed at SOHO ranged between 303 and 476 km/sec. The high latitude magnetometer at Andenes recorded quiet to severe storm levels. A solar wind shock was observed at DSCOVR at 02:09 on August 5, the arrival of the August 2 CME.

Solar flux density measured at 20h UT on 2.8 GHz was 175.8 - decreasing 3.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 150.95. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 35 (STAR Ap - based on the mean of three hour interval ap indices: 35.3). Three hour interval K indices: 56553211 (planetary), *7553222 (Boulder), 67643222 (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 17 active regions using 2K resolution (SN: 271) and in 11 active regions using 1K resolution (SN: 155) SDO/HMI images.

Region 13386 [N10W75] became more complex as the two largest opposite polarity spots partly merged before noon. This merge and subsequent increase in magnetic shear, was the likely cause of the X1 flare late in the day.
Region 13387 [N20W47] developed with new flux emerging to the south of the largest spot. The new penumbra has spots of both polarities and an M class flare is possible.
Region 13388 [S23W57] was quiet and stable.
Region 13389 [S11W41] was quiet and stable.
Region 13390 [S19W29] was quiet and stable.
Region 13391 [N23W12] decayed slowly and quietly.
Region 13392 [N09W21] decayed slowly and produced a few flares.
Region 13394 [S22E37] was mostly quiet and stable.
Region 13395 [N14E52] was mostly quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S8814 [N19E06] decayed slowly and quietly.
S8823 [S20W17] decayed early in the day, then developed slowly after noon.
New region S8825 [N21W22] was split off from AR 13391 when a tiny positive polarity spot became visible before noon.
New region S8826 [N34W18] emerged with a few spots.
New region S8827 [N27E03] emerged with tiny spots.
New region S8828 [N22E27] was observed with tiny spots in an old plage area.
New region S8829 [N14E33] emerged with a tiny spot.
New region S8830 [N18W03] was observed with tiny spots in an old plage area.

AR S8813 produced a C1.9 flare at 01:30 UT from behind the southwest limb.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.6 00:35 behind SW limb S8813 GOES16  
C2.3 00:50   13387 GOES16  
C2.0 02:06   S8813 GOES16  
C2.5 02:18   S8813 GOES16  
C3.7 02:23 N21W39 13387 GOES16 simultaneous flare in AR S8813
C9.7 02:54 behind SW limb S8813 GOES16  
C3.4 04:25   13387 GOES16  
C2.9 04:49   13387 GOES16  
C3.3 05:11   13387 GOES16  
C5.6/1F 05:29 N19W37 13387 GOES16  
C4.7 05:42   13387 GOES16  
M1.6/1N 07:18 N10W63 13386 GOES16 LDE, moderate type II radio sweep, full halo CME
M2.1 09:35 behind SW limb S8813 GOES16  
C3.0 12:01   13394 GOES16  
C2.1 14:16   13386 GOES16  
C3.1 14:49 N20W41 13387 GOES16  
C2.2 15:14   13386 GOES16  
C2.4 16:25 N21W47 13387 GOES16 simultaneous flare in AR S8813
C2.8 16:58 N07W73 13386 GOES16  
C6.7 19:10 N23W45 13387 GOES16  
C2.1 20:14   13387 GOES16  
C3.0 20:39 N22W46 13387 GOES16  
C2.5 21:16   13387 GOES16  
X1.6 22:21   13386 GOES16 weak type II radio sweep, full halo CME

Coronal mass ejections (CMEs)

August 3: No obviously Earth directed CMEs were observed.
August 4: An asymmetrical full halo CME was observed after the long duration M1.9 event in AR 13386 peaking at 04:24 UT. The CME could reach Earth on August 7.
August 5: An asymmetrical full halo CME was observed after the long duration M1.6 event in AR 13386 peaking at 07:18 UT. The CME could reach Earth on August 8. Another asymmetrical full halo CME was observed after the X1.6 event in AR 13386 peaking at 22:21 UT. This CME could also reach Earth on August 8.

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]

No obvious coronal holes are currently in or near Earth facing positions.

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 August 6. The arrival of the August 4 and 5 CMEs will likely cause quiet to minor storm conditions on August 7-9.

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
13386 2023.07.25
2023.07.26
5 7 3 N11W76 0250 DKI DKC

beta-delta

area: 0640

location: N10W75

13387 2023.07.26
2023.07.27
4 12 7 N22W49 0080 DSO DSI

beta-delta

area: 0210

location: N20W47

13388 2023.07.26
2023.07.27
1 2 1 S23W58 0010 AXX HRX  
13389 2023.07.27
2023.07.27
  3   S09W47 0005   BXO

location: S11W41

S8806 2023.07.27       S15W55            
13390 2023.07.28
2023.07.27
  6 2 S20W36 0012   BXO

location: S19W29

13391 2023.07.28
2023.07.29
1 6 4 N23W14 0080 HSX CSO area: 0160

location: N23W12

13392 2023.07.29
2023.07.31
13 16 9 N10W20 0190 CAO CAO area: 0240

location: N09W21

13393 2023.07.29
2023.07.31
      N17W44          
S8814 2023.07.31   10   N19E06 0015   BXO  
13394 2023.08.02
2023.08.03
2 9 6 S22E36 0150 HSX CHO area: 0280

location: S22E37

S8817 2023.08.02       S09W20          
S8818 2023.08.02       N17E16            
13395 2023.08.03 4 10 5 N13E52 0120 DSO DSO

location: N14E52

area: 0170

S8820 2023.08.03       S16W56            
S8821 2023.08.03       N32E58            
S8822 2023.08.03       S11E08            
S8823 2023.08.04   6 5 S20W17 0020   CRO  
S8824 2023.08.04       S26W02          
S8825 2023.08.05   3 1 N21W22 0010   AXX    
S8826 2023.08.05   3 2 N34W18 0015   CRO    
S8827 2023.08.05   2   N27E03 0002   BXO    
S8828 2023.08.05   2   N22E27 0002   AXX    
S8829 2023.08.05   1   N14E33 0001   AXX    
S8830 2023.08.05   3   N18W03 0005   BXO    
Total spot count: 30 101 45  
Sunspot number: 100 271 155  (total spot count + 10 * number of spotted regions)
Weighted SN: 65 150 94  (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): 110 149 124  

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
2022.01 103.8 100.5 55.3 60.1 (+4.2) 8.92
2022.02 109.1 106.5 60.9 64.7 (+4.6) 10.46
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 92.5 (+5.8) 10.92
2022.09 135.1 136.5 96.0 96.4 (+3.9) 12.18
2022.10 133.5 132.7 95.5 98.7 (+2.3) 11.16
2022.11 123.4 120.7 80.5 101.0 (+2.3) 9.33
2022.12 147.9 143.4 112.8 106.6 (+5.6) 10.99
2023.01 182.4 176.6 143.6 113.3 (+6.7) 8.73
2023.02 167.2 163.2 110.9 (119.1 projected, +5.8) 14.48
(current
SC25 peak)
2023.03 157.2 155.6 122.6 (124.4 projected, +5.3) 14.42
2023.04 145.4 146.4 96.4 (130.5 projected, +6.1) 13.40
2023.05 155.6 159.2 137.9 (136.1 projected, +5.6) 10.67
2023.06 161.7 166.8 163.4 (139.3 projected, +3.2) 8.95
2023.07  176.4 182.2 159.1 (139.7 projected, +0.4) 8.15
2023.08  171.4 (1)   20.7 (2A) / 128.2 (2B) / 148.9 (2C) (141.5 projected, +1.8) (14.7)
2023.09       (145.0 projected, +3.5)  
2023.10       (146.8 projected, +1.8)  
2023.11       (149.4 projected max SC25, +2.6)  
2023.12       (148.6 projected, -0.8)  
2024.01       (145.7 projected, -2.9)  
2024.02       (144.3 projected, -1.4)  

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

 

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.