Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 28, 2024 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 (August 4, 2024)
Solar cycle Solar cycles 23-25 (August 11, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (August 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 (August 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (August 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 quiet to unsettled levels on August 27. The high latitude magnetometer at Andenes recorded quiet to minor storm 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 211.9 - decreasing 23.2 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 172.46. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 172.46 on February 28, 2024). The Potsdam WDC planetary A index was 25 (STAR Ap - based on the mean of three hour interval ap indices: 24.6). Three hour interval K indices: 01323323 (planetary), 12323433 (Boulder), 20223355 (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 19 active regions using 2K resolution (SN: 387) and in 15 active regions using 1K resolution (SN: 246) SDO/HMI images.

AR 13790 [S10W85] rotated quietly to the southwest limb.
AR 13792 [S18W70] was quiet and stable.
AR 13796 [S03W53] decayed slowly and produced a few flares.
AR 13798 [N07W32] was quiet and stable.
AR 13799 [S10W20] developed slowly and quietly.
AR 13800 [S27W35] produced several C flares.
AR 13801 [N08W01] decayed slowly and was mostly quiet.
AR 13802 [N13W64] decayed slowly and quietly.
AR 13803 [N14E57] was mostly quiet and stable.
AR 13804 [S24E49] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S10033 [S05W34] was quiet and stable.
S10045 [N11W41] was quiet and stable.
S10047 [N27W04] reemerged with tiny spots.
S10048 [N13W19] was quiet and stable.
S10059 [N08E45] was quiet and stable.
New region S10061 [S16E38] emerged with tiny spots.
New region S10062 [S10E82] rotated into view with a few spots.
New region S10063 [N09E24] emerged with a tiny spot.
New region S10064 [S08E47] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment

Coronal mass ejections (CMEs)

August 25-27: 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]

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 to fair.

Forecast

The geomagnetic field is expected to be at quiet to unsettled levels on August 28-31.

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
13790 2024.08.15
2024.08.15
12 2   S13W88 0280 DKI HAX

location: S10W85

barely visible at the limb

13792 2024.08.16
2024.08.16
2 3 2 S17W73 0320 HHX HHX

location: S18W70

area: 0450

13793 2024.08.16
2024.08.17
      N22W86        

 

13796 2024.08.17
2024.08.18
14 27 17 S04W53 0240 DSI DAI beta-gamma

location: S03W53

area: 0300

13795 2024.08.17
2024.08.18
      N09W52           location: N02W48
S10033 2024.08.18   5   S05W34 0007   AXX  
13798 2024.08.19
2024.08.19
1 5 3 N06W32 0030 HSX CSO

area: 0050

location: N07W32

13799 2024.08.20
2024.08.21
11 39 19 S10W18 0350 EKI EHO

area: 0530

location: S10W20

13800 2024.08.20
2024.08.22
15 35 24 S27W34 0420 EHI EHI beta-gamma

location: S27W35

area: 0520

13801 2024.08.21
2024.08.22
5 34 8 N09W01 0120 CSO CSO

area: 0240

location: N08W01

S10045 2024.08.21   2   N11W41 0003   AXX  
S10046 2024.08.22       N13W08            
S10047 2024.08.22   3 2 N21W04 0006   AXX    
S10048 2024.08.22   5 2 N13W19 0010   BXO  
S10049 2024.08.22       S20W07            
S10050 2024.08.22       S29W32            
13802 2024.08.23
2024.08.25
2 5 1 N13W63 0010 BXO BXO

location: N13W64

S10054 2024.08.24       S08E18            
S10055 2024.08.24       S33W34            
13803 2024.08.25
2024.08.26
7 14 8 N12E57 0060 DAO DAO location: N14E57

area: 0210

13804 2024.08.25
2024.08.26
1 3 2 S25E49 0030 HSX HSX location: S24E49

area: 0110

S10059 2024.08.26   4 2 N08E45 0010   BXO  
S10060 2024.08.26       S07E67          
S10061 2024.08.27   4 2 S16E38 0010   BXO    
S10062 2024.08.27   5 3 S10E82 0350   CAO    
S10063 2024.08.27   1 1 N09E24 0003   AXX    
S10064 2024.08.27   1   S08E47 0002   AXX    
Total spot count: 70 197 96  
Sunspot number: 170 387 246  (total spot count + 10 * number of spotted regions)
Weighted SN: 135 262 161  (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): 187 213 197  

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
2022.11 123.4 120.7 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  176.4 182.2 160.0 124.6 (-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 (137.4 projected, +6.3) 5.31
2024.03 154.4 152.9 103.7 (144.1 projected, +6.7) 11.03
2024.04 161.3 162.6 136.5 (148.2 projected, +4.1) 9.69
2024.05 187.7 191.9 171.7 (152.9 projected, +4.7) 23.56
(SC25 peak)
2024.06 184.3 190.2 164.2 (156.9 projected, +4.0) 10.24
2024.07 196.6
(cycle peak)
203.0 196.5  (SC25 peak) (158.7 projected, +1.8) 7.13
2024.08  250.6 (1)   182.5 (2A) / 209.5 (2B) / 226.3 (2C)
[projected ISN: 221]
(159.1 projected, +0.4) (15.3)
2024.09       (161.0 projected, +1.9)  
2024.10       (162.8 projected, +1.8)  
2024.11       (160.8 projected, -2.0)  
2024.12       (156.4 projected, -4.4)  
2025.01       (150.3 projected, -6.1)  
2025.02       (143.0 projected, -7.3)  

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

Update on the progress of solar cycle 25 as of August 12, 2024

Sunspot counts in July 2024 were the highest we've seen for a single month during solar cycle 25. The first part of August has seen very high sunspot counts, and there more than a remote possibility that we'll see activity in August approaching the most active months of solar cycle 23. With at least 4 consecutive months of high sunspot counts the projected peak for the smoothed ISN (365 days smoothing) has increased significantly to above 160. The month of the peak is currently likely to occur sometime between July and November 2024.

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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.