Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 18, 2023 at 05:55 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 (July 6, 2023)
Solar cycle Solar cycles 23-25 (July 1, 2023) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (July 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 (July 1, 2023) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (July 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 July 17 due to CME effects (most likely related to the July 14 CME). Solar wind speed at SOHO ranged between 406 and 618 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 180.0 - decreasing 0.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 147.42. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 19.0). Three hour interval K indices: 32443244 (planetary), 32443344 (Boulder), 32354354 (Andenes).

The background x-ray flux was at the class C1 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 295) and in 11 active regions using 1K resolution (SN: 194) SDO/HMI images.

Region 13363 [S21W72] decayed with the large penumbra partly splitting in the south. A major long duration M5.7 flare peaked at 00:06 UT on July 18. A proton event began at 00:20 UT and the above 10 MeV flux has so far peaked at 609 pfu at 05:00 today. A large and wide partial halo CME was observed before the flare peaked, LASCO C2 imagery displays the initial part of the CME at 23:36 UT.
Region 13370 [S14W33] was quiet and stable.
Region 13371 [S15W19] decayed slowly and quietly.
Region 13372 [N23E02] decayed and has only a small magnetic delta remaining in the easternmost trailing penumbra. M flares are still possible.
Region 13373 [N08E28] developed further with the magnetic delta structure in the intermediate spot section enlarging. A major flare is possible. C1 flares: C1.6 @ 02:48 UT
Region 13374 [S08E28] was quiet and stable.
New region 13375 [N12W52] emerged on July 15 and began to decay when it was numbered by SWPC 2 days later.
New region 13376 [N24E43] developed many spots and was numbered by SWPC 2 days after the first spots were observed.
New region 13377 [S09E74] rotated into view with a few spots. C flares are possible.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S8764 [N16W21] was quiet and stable.
S8767 [N19W46] decayed slowly and quietly.
New region S8775 [S27E73] rotated into view with a small spot.
New region S8776 [S06W15] emerged with a tiny spot.
New region S8777 [S19E28] was observed with a tiny spot in an old plage region.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 00:07   13363 GOES16  
C2.7 01:42   13377 GOES16  
C2.2 02:14   13363 GOES16  
C2.2 03:23   13377 GOES16  
C4.4 03:40   13377 GOES16 incorrectly attributed to AR 13363 by SWPC
C4.1 03:53   13363 GOES16  
C2.8 04:34 N08E43 13373 GOES16  
C2.9 04:43   13377 GOES16  
C3.9 05:16   13377 GOES16 incorrectly attributed to AR 13372 by SWPC
C3.7 06:04 N08E43 13373 GOES16  
C4.3 06:55 N09E38 13373 GOES16  
C3.7 08:18 N08E43 13373 GOES16  
C4.3 06:55 N09E38 13373 GOES16  
C3.7 08:18   13373 GOES16  
C4.2 09:26 S25W70 13363 GOES16  
C2.6 10:29   13373 GOES16  
C2.7 11:08   13363 GOES16  
C3.4 11:21   13372 GOES16  
C3.5 11:52   13372 GOES16  
C2.9 12:18   13373 GOES16  
C3.0 12:43   13363 GOES16  
C2.5 13:02   13373 GOES16  
C3.3 14:55   13363 GOES16  
C6.6 15:16 N27E12 13372 GOES16  
C2.6 16:14   13363 GOES16  
C2.5 17:33 N06E32 13373 GOES16  
C2.4 17:41   13373 GOES16  
C3.2 18:29   13377 GOES16  
C2.9 18:54   13363 GOES16  
C3.3 20:01 N07E30 13373 GOES16  
C5.9 22:11   13373 GOES16  
C7.4 22:32   13363 GOES16  
M2.7 22:54   13363 GOES16  
M5.7 00:06   13363 GOES16 SWPC has 23:37 UT as the start time for the flare, the leading CME edge was observed one minute earlier
Using SDO/AIA imagery the start time was likely near 23:15 UT
Proton event. Large partial halo CME

Coronal mass ejections (CMEs)

July 15-16: No obviously Earth directed CMEs were observed.
July 17-18: An asymmetrical full halo CME was observed after an M5 flare in AR 13363 at 00:06 UT on July 18. Due to the source location near the southwest limb it is uncertain when the CME will reach Earth, currently the estimate is sometime between late on July 19 and early on July 21.

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 southern hemisphere coronal hole (CH1161) will be in an Earth facing position on July 18.

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 poor due to proton event effects. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to active on July 18 due to CME effects. Quiet to unsettled is likely on July 19. It is uncertain when the July 17/18 CME will reach Earth, unsettled to major storm levels are likely on July 20-21. Effects from CH1161 will probably not be noticeable due to CME effects.

Coronal holes (1) Coronal mass ejection (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
13363 2023.07.05
2023.07.06
10 16 7 S22W74 0700 DKO CKO location: S21W72
13370 2023.07.09
2023.07.10
  2   S15W34 0002   BXO

location: S14W33

13371 2023.07.10
2023.07.11
1 4 2 S15W19 0020 HRX HRX

 

S8752 2023.07.10       N17W40            
S8753 2023.07.10       S29W23            
13372 2023.07.11
2023.07.11
21 36 20 N23E02 0700 FHO FHO

beta-delta

area: 0950

S8756 2023.07.11       S15W41            
S8758 2023.07.12       N26W36            
S8761 2023.07.13       N22W52            
13373 2023.07.13
2023.07.14
20 39 22 N07E25 0450 EKC EKC beta-gamma-delta

area: 0920

location: N08E28

13374 2023.07.13
2023.07.14
1 6 2 S16E27 0030 HRX CAO area: 0050

location: S08E28

S8764 2023.07.13   10 3 N16W21 0020   AXX  
S8765 2023.07.13       S00W03            
S8766 2023.07.14       N27W17            
S8767 2023.07.15   2 1 N19W46 0003   BXO  
S8768 2023.07.15       S24W08            
13375 2023.07.15
2023.07.17
4 7 4 N12W53 0020 CRO BXO  
S8771 2023.07.15       S32E34            
13376 2023.07.15
2023.07.17
11 25 18 N24E43 0030 DRO DRI  
S8773 2023.07.16       S28W38          
13377 2023.07.17
2023.07.17
1 5 4 S09E71 0030 DSO DAO   was AR S8774

location: S09E74

area: 0390

S8775 2023.07.17   1 1 S27E73 0020   HRX    
S8776 2023.07.17   1   S06W15 0002   AXX    
S8777 2023.07.17   1   S19E28 0001   AXX    
Total spot count: 69 155 84  
Sunspot number: 149 295 194  (total spot count + 10 * number of spotted regions)
Weighted SN: 116 204 133  (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): 165 162 155  

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
2021.12 103.0 99.8 67.5 55.9 (+5.1) 6.40
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 (113.7 projected, +6.1) 8.73
2023.02 167.2 163.2 110.9 (118.5 projected, +4.8) 14.48
(current
SC25 peak)
2023.03 157.2 155.6 122.6 (121.6 projected, +3.1) 14.42
2023.04 145.4 146.4 96.4 (127.0 projected, +5.4) 13.40
2023.05 155.6 159.2 137.9 (132.7 projected, +5.7) 10.67
2023.06 161.7 166.8 163.4 (135.9 projected, +3.2) 8.9
2023.07  177.2 (1)   80.3 (2A) / 146.4 (2B) / 169.9 (2C) (135.4 projected, -0.5) (7.9)
2023.08       (136.4 projected, +1.0)  
2023.09       (139.8 projected, +3.4)  
2023.10       (141.6 projected, +1.8)  
2023.11       (144.2 projected max SC25, +2.6)  
2023.12       (143.4 projected, -0.1)  
2024.01       (140.1 projected, -3.3)  

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.