Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 17, 2023 at 07:00 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 16 due to CME effects. Solar wind speed at SOHO ranged between 317 and 544 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. A solar wind shock was observed at 18:38 UT at SOHO. The source of this CME is uncertain.

Solar flux density measured at 20h UT on 2.8 GHz was 184.3 - increasing 15.5 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 147.37. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.8). Three hour interval K indices: 01001134 (planetary), 11113324 (Boulder), 20012035 (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 11 active regions using 2K resolution (SN: 255) and in 10 active regions using 1K resolution (SN: 176) SDO/HMI images.

Region 13363 [S22W59] still has a magnetic delta structure in the main penumbra and produced a number of flares. A major flare is possible. C1 flares: C1.7 @ 02:08, C1.9 @ 04:56, C1.8 @ 05:49, C1.8 @ 09:02, C1.5 @ 11:38, C1.9 @ 13:44 UT
Region 13370 [S16W17] decayed slowly and quietly.
Region 13371 [S16W06] was quiet and stable.
Region 13372 [N23E14] has a magnetically complex trailing spot section and is likely to produce further M class flares. C1 flares: C1.9 @ 00:54, C1.7 @ 12:38, C1.5 @ 13:05, C1.7 @ 13:32 UT
Region 13373 [N08E40] developed further and became more complex in the central spot section with both polarities in one penumbra. M flares are likely. C1 flares: C1.4 @ 02:38 UT
Region 13374 [S08E41] was mostly quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S8764 [N16W10] was quiet and stable.
S8767 [N19W31] decayed slowly and quietly.
S8769 [N13W40] developed slowly and was quiet.
S8772 [N24E57] developed slowly and quietly.
New region S8773 [S28W25] emerged with tiny spots.

Multiple impressive fast, wide full halo CMEs were observed during the day from a source several days behind the west limb.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 00:45   13363 GOES16  
C2.5 01:07   13363 GOES16  
C2.1 01:16   13363 GOES16  
C2.1 06:08 N27E28 13372 GOES16  
C2.4 06:54   13374 GOES16  
M1.0 08:26   13372 GOES16  
C4.7 08:41   13363 GOES16  
C3.8 08:50   13363 GOES16  
C2.9 10:33 S24W53 13363 GOES16  
C3.0 14:03   13373 GOES16  
M1.7/1B 15:08 N23E27 13372 GOES16 moderate type IV radio sweep
C2.5 17:14   13372 GOES16  
C5.7 17:19   13363 GOES16  
M4.0/2B 17:46 S23W58 13363 GOES16  
C6.2/1F 19:14 S21W62 13363 GOES16 weak type II and moderate type IV radio sweeps
C5.2 19:19 S22W60 13363 GOES16  
C2.4 20:35   13372 GOES16  
C3.5 20:45   13373 GOES16 simultaneous flare in AR 13363
C4.2 20:54   13372 GOES16  
C3.7 21:05   13363 GOES16  
C2.1 22:56 behind southeast limb   GOES16  

Coronal mass ejections (CMEs)

July 15-16: No obviously Earth directed CMEs were observed.
July 14: A CME was observed after an M1 flare in AR 13363 at 09:36 UT. While the main ejecta is not heading towards Earth, there is a chance a component of the CME could impact Earth on July 17.

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 likely rotate into 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 poor. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to active on July 17-19 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
13362 2023.07.04
2023.07.05
      S08W87            
13363 2023.07.05
2023.07.06
9 24 15 S22W59 0720 DKO DKC beta-delta
13364 2023.07.05
2023.07.06
      N25W79          

 

13370 2023.07.09
2023.07.10
  2   S15W20 0002   BXO

location: S16W17

13371 2023.07.10
2023.07.11
1 6 1 S15W07 0020 HRX HAX area: 0040

location: S16W06

S8752 2023.07.10       N17W27            
S8753 2023.07.10       S29W10          
13372 2023.07.11
2023.07.11
18 49 23 N23E13 0700 FKO FHO

beta-gamma-delta

location: N23E14

area: 1040

S8756 2023.07.11       S15W28            
S8757 2023.07.11       N21W50            
S8758 2023.07.12       N26W23            
S8759 2023.07.12       S01W47            
S8761 2023.07.13       N22W39            
13373 2023.07.13
2023.07.14
20 30 21 N07E39 0240 DAI EAC beta-gamma-delta

area: 0670

location: N08E41

13374 2023.07.13
2023.07.14
1 4 2 S08E41 0020 HSX HAX area: 0080
S8764 2023.07.13   7 2 N16W10 0015   AXX    
S8765 2023.07.13       S00E10            
S8766 2023.07.14       N27W04            
S8767 2023.07.15   5 2 N19W31 0015   CRO  
S8768 2023.07.15       S24E05          
S8769 2023.07.15   6 4 N13W40 0040   CRO  
S8770 2023.07.15       N27W53          
S8771 2023.07.15       S32E47          
S8772 2023.07.15   9 4 N24E57 0020   BXO  
S8773 2023.07.16   3 2 S28W25 0010   BXO    
Total spot count: 49 145 76  
Sunspot number: 99 255 176  (total spot count + 10 * number of spotted regions)
Weighted SN: 72 186 117  (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): 109 140 141  

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  177.1 (1)   75.5 (2A) / 146.2 (2B) / 170.8 (2C) (135.4 projected, -0.5) (7.2)
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.