Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 3, 2024 at 08:45 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 (January 1, 2024)
Solar cycle Solar cycles 23-25 (January 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (January 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 (January 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (January 1, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (January  3, 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 (new)

Recent activity

The geomagnetic field was quiet to unsettled on January 2. Solar wind speed at SOHO ranged between 353 and 483 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels. An unimpressive solar wind shock was recorded at 05:02 UT on January 3 at SOHO, most likely the arrival of the December 31 CME.

Solar flux density measured at 20h UT on 2.8 GHz was 142.1 - increasing 12.2 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 158.43. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.71 on June 27, 2023). 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: 32122321 (planetary), 32123212 (Boulder), 44112432 (Andenes).

The background x-ray flux is at the class B6 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 199) and in 8 active regions using 1K resolution (SN: 119) SDO/HMI images.

Region 13534 [S13W24] decayed further and was quiet.
Region 13536 [N04E49] lost the magnetic delta structure and produced mostly low level C flares. The region still has an east-west oriented inversion line. C1 flares: C1.3 @ 04:07, C1.4 @ 06:05, C1.1 @ 07:43, C1.2 @ 10:29, C1.1 @ 17:24, C1.2 @ 17:52, C1.9 @ 2021,  C1.1 @ 22:03 UT
New region 13537 [N17E47] emerged on January 1 and was numbered the next day by SWPC. C1 flares: C1.2 @ 01:39 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9273 [S09W00] was quiet and stable.
S9278  [S07W77] developed early in the day, then decayed slowly. C1 flares: C1.2 @ 13:45, C1.1 @ 15:30 UT
S9279 [N08E58] was mostly quiet and stable.
S9283 [N21E23] was quiet and stable.
S9286 [N07W27] was quiet and stable.
New region S9287 [N20E35] emerged with a tiny spot.
New region S9288 [N19W02] emerged with tiny spots.
New region S9289 [S13E10] emerged with tiny spots.

The above 10 MeV proton flux appears to have peaked near 8.2 pfu near 07 UT on January 3.

An active region behind the northeast limb produced a C1.5 flare at 00:49 and a C1.6 flare at 04:37 UT. SWPC incorrectly assigned these flares to AR 13537.
AR 13533 behind the northwest limb was the source of a C1.2 flare at 03:19 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.0 06:51 N05E58 13536 GOES16 simultaneous flare in AR S9279
C2.0 07:15   S9279 GOES16  
C2.9 09:32 N04E56 13536 GOES16  
C2.5 09:52   13536 GOES16  
M1.1 18:29   13536 GOES16  
C2.1 20:37   13536 GOES16  
C2.1 20:57   13536 GOES16  

Coronal mass ejections (CMEs)

January 1-2: No obviously Earth directed CME observed.
December 31: A very fast partial halo CME was observed after the X5 flare in AR 13536. A weak solar wind shock was observed early on January 3.

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 recurrent negative polarity trans equatorial coronal hole (CH1195) was Earth facing on December 28-31.

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 to very poor. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 3-4 due to CME effects. Quiet conditions are likely on January 5-6.

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
13535 2023.12.24
2023.12.28
2     S08W79          

location: S06W84

spotless

previous day SWPC position: S05W75
SWPC has moved the location of this AR to that of trailing AR S9278

13534 2023.12.26
2023.12.27
4 11 4 S12W22 0010 BXO CRO

location: S13W24

area: 0025

S9269 2023.12.27       N20W35          
S9271 2023.12.29       N00W41            
S9273 2023.12.29   7 2 S09W00 0015   BXO  
S9275 2023.12.30       S02W31            
S9276 2023.12.31       N17W47            
13536 2023.12.31
2023.12.31
11 21 12 N05E49 0240 EAI DAC beta-gamma

location: N04E49

S9278 2023.12.31   4 2 S07W77 0015   CRO  
S9279 2023.12.31   19 9 N08E58 0090   DAO beta-gamma
S9280 2023.12.31       N20W20            
S9281 2023.12.31       N08E19            
S9282 2023.12.31       S18W14          
S9283 2023.12.31   2   N21E23 0002   AXX  
S9284 2024.01.01       S01E08          
13537 2024.01.01
2024.01.02
2 13 7 N18E48 0040 CAO CAO area: 0100

location: N17E47

S9286 2024.01.01   5 2 N07W27 0008   AXX  
S9287 2024.01.02   1   N20E35 0001   AXX    
S9288 2024.01.02   2 1 N19W02 0005   AXX    
S9289 2024.01.02   4   S13E10 0006   BXO    
Total spot count: 19 89 39  
Sunspot number: 59 199 119  (total spot count + 10 * number of spotted regions)
Weighted SN: 29 110 60  (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): 65 109 95  

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
2022.05 133.8 136.8 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 92.6 (+5.9) 10.92
2022.09 135.1 136.5 96.0 96.5 (+3.9) 12.18
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
(current
SC25 peak)
2023.03 157.2 155.6 123.3 121.0 (+3.2) 14.42
2023.04 145.4 146.4 97.6 122.7 (+1.7) 13.40
2023.05 155.6 159.2 137.4 123.9 (+1.2) 10.67
2023.06 161.7 166.8 160.5 125.0 (+1.1)
(SC25 solar max candidate)
8.95
2023.07  176.4 182.2 159.1 (124.6 projected, -0.4) 8.15
2023.08  153.7 157.6 114.8 (124.1 projected, -0.5) 7.19
2023.09  154.4 156.0 133.6 (123.8 projected, -0.3) 14.26
2023.10  142.8 141.9 99.4 (124.6 projected, +0.8) 8.16
2023.11 153.5 150.2 105.4 (124.6 projected, +0.0) 12.20
2023.12 151.1 146.4 114.2 (121.2 projected, -3.4) 9.7
2024.01 138.9 (1)   3.3 (2A) / 51.5 (2B) / 134.6 (2C) (117.9 projected, -3.3) (8.4)
2024.02       (117.1 projected, -0.8)  
2024.03       (116.6 projected, -0.5)  
2024.04       (116.6 projected, +0.0)  
2024.05       (117.0 projected, -0.8)  
2024.06       (114.9 projected, -2.1)  

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 January 3, 2024

Due to relatively low solar activity during the last months of 2023, the possibility that solar cycle 25 has already peaked has increased significantly. Whether the first peak in June 2023 will be the actual solar max will not be known for some time. Due to the relatively high solar activity early in 2023 it is unlikely there will be another solar max candidate, if at all, until at least May 2024. Both the northern and southern polar fields, as well as the averaged total field, have already reversed polarities.

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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.