Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 4, 2024 at 03:25 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 3, 2024)
Solar cycle Solar cycles 23-25 (July 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (July 1, 2024) 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, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (July 1, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (June 17, 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 very quiet levels on July 3. 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 167.4 - decreasing 23.5 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 163.20. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 163.22 on January 1, 2024). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.1). Three hour interval K indices: 11111111 (planetary), 55252103 (lately erroneous measurements from Boulder), 32002012 (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 15 active regions using 2K resolution (SN: 319) and in 11 active regions using 1K resolution (SN: 196) SDO/HMI images.

Region 13722 [S13W82] decayed slowly and quietly.
Region 13723 [S20W53] decayed slowly and quietly.
Region 13727 [S18W44] decayed slowly and quietly.
Region 13728 [S25W40] was quiet and stable.
Region 13729 [S04W25] decayed slowly and produced several C flares. C1 flares: C1.8 @ 00:33, C1.6 @ 04:27, C1.6 @ 09:01, C1.8 @ 15:11 UT
Region 13730 [S18W71] decayed slowly and was the origin of several flares.
Region 13731 [S16W18] decayed slowly and quietly.
Region 13733 [N04W26] developed further and could produce M flares.
Region 13734 [N08E11] decayed losing spots and area.
Region 13735 [N16E22] was quiet and stable.
New region 13736 [S18E66] rotated into view on July 2 and was numbered the next day by SWPC. C1 flares: C1.5 @ 06:51, C1.3 @ 07:15, C1.8 @ 10:12 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9855 [S13W63] was mostly quiet and stable.
S9858 [S20E13] was quiet and stable.
New region S9859 [S27E67] emerged with a few spots.
New region S9860 [S04W10] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.9 01:35   13729 GOES16 LDE
C2.5 03:32   13729 GOES16  
C2.0 05:58   13736 GOES16  
C2.2 07:33   13736 GOES16  
M1.5/1N 07:41 S20W62 13730 GOES16 strong type II radio sweep, CME
C2.2 09:46   13736 GOES16  
C2.5 11:01 S20W66 13730 GOES16  
C2.5 12:11   13729 GOES16  
C2.3 15:20   13729 GOES16  
C2.5 19:26   13729 GOES16  

Coronal mass ejections (CMEs)

July 1-3: No obviously Earth directed CMEs 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 negative polarity southern hemisphere coronal hole (CH1230) could rotate into an Earth facing position on July 6-7.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on July 4-7.

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
13721 2024.06.21
2024.06.21
      N26W82          
13722 2024.06.21
2024.06.21
1 2   S11W82 0040 HSX HRX area: 0030

location: S13W82

13723 2024.06.22
2024.06.23
  1   S18W61 0001   AXX

location: S20W53

13726 2024.06.22
2024.06.23
      S04W85           location: S05W64
13724 2024.06.23 1     S15W83 0030 HSX       SWPC split this off from AR 13722
13728 2024.06.23
2024.06.25
  8 1 S26W52 0015   BXO

location: S25W40

13727 2024.06.24
2024.06.25
4 8 4 S19W46 0120 CAO CAO area: 0140

location: S18W44

S9830 2024.06.24       S07W45            
13729 2024.06.25
2024.06.26
35 58 36 S05W26 0240 FAI FAI

beta-gamma

area: 0340

location: S04W25

This AR is considered for split into 3 ARs

13730 2024.06.26
2024.06.27
4 2 2 S18W72 0010 BXO CRO location: S18W71
13731 2024.06.26
2024.06.28
4 5 1 S16W20 0010 AXX BXO

location: S16W18

S9837 2024.06.27       N09W47            
S9838 2024.06.27       N26W45          
13732 2024.06.28 5     S20W54 0010 DRO       Apparently SWPC has moved the location from the leading spot section of AR 13727 to the trailing spot section of AR 13723
13733 2024.06.28
2024.06.29
8 34 22 N05W29 0050 DSI DAI beta-gamma

location: N04W26

area: 0280

13734 2024.06.28
2024.06.29
7 25 9 N09E18 0060 CAO CAO location: N08E11

SWPC location is way off

S9843 2024.06.28       N09W27            
S9844 2024.06.28       N12W56            
S9845 2024.06.28       S30W36            
13735 2024.06.29
2024.06.29
1 5 3 N17E20 0040 HSX CSO

area: 0060

location: N16E22

S9847 2024.06.29       S13W07            
S9849 2024.06.29       S16W22            
S9851 2024.06.30       S40W09            
S9854 2024.07.01       N23W07            
S9855 2024.07.01   7 4 S13W63 0080   DAO  
S9856 2024.07.01       S28W18            
13736 2024.07.02
2024.07.03
2 7 3 S18E65 0060 CSO DSO location: S18E66

area: 0220

S9858 2024.07.02   3   S20E13 0004   BXO  
S9859 2024.07.03   3 1 S27E67 0007   BXO    
S9860 2024.07.03   1   S04W10 0002   AXX    
Total spot count: 72 169 86  
Sunspot number: 182 319 196  (total spot count + 10 * number of spotted regions)
Weighted SN: 115 210 127  (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): 200 175 157  

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
2022.10 133.5 132.7 95.5 98.9 (+2.4) 11.16
2022.11 123.4 120.7 80.5 101.2 (+2.3) 9.33
2022.12 147.9 143.4 112.8 106.7 (+5.5) 10.99
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  176.4 182.2 160.0 124.4 (-0.9) 8.15
2023.08  153.7 157.6 114.8 124.1 (-0.3) 7.19
2023.09  154.4 156.0 134.2 123.9 (-0.2) 14.26
2023.10  142.8 141.9 99.4 124.8 (+0.9) 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
2024.01 164.6 159.3 123.0 (128.9 projected, -0.5) 5.46
2024.02 172.5 168.3 124.7 (129.4 projected, +0.5) 5.31
2024.03 154.4 152.9 104.9 (130.3 projected, +0.9) 11.03
2024.04 161.3 162.6 136.5 (131.0 projected, +0.7) 9.69
2024.05 187.7
(cycle peak)
191.9 171.7 (SC25 peak) (133.2 projected, +2.2) 23.56
(SC25 peak)
2024.06 184.3 190.2 164.2 (134.9 projected, +1.7) 9.9
2024.07 167.3 (1)   18.3 (2A) / 188.7 (2B) / 160.8 (2C) (134.8 projected, -0.1) (4.3)
2024.08       (134.3 projected, -0.5)  
2024.09       (134.4 projected, +0.1)  
2024.10       (134.3 projected, -0.1)  
2024.11       (132.3 projected, -2.0)  
2024.12       (128.0 projected, -4.3)  
2025.01       (124.0 projected, -4.0)  

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 June 6, 2024

May 2024 easily became the month with the highest sunspot counts during solar cycle 25, and early June has seen no change in that pattern of many spot groups, some of which are large and complex. The next candidate for solar max is still uncertain, however, May 20-21, 2024 has all of the smoothed 365d sunspot numbers as well as the 365d smoothed solar flux signalling a peak on those days.

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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.