Solar Terrestrial Activity Report

Activity chart

Last major update issued on April 26, 2022 at 10:25 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 (March 1, 2022)
Solar cycle Solar cycles 23-25 (March 1, 2022) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (March 1, 2022) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (June 1, 2020) POES auroral activity level October 2009 - December 2012]
  Comparison of cycles 21-25 (March 1, 2022) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (March 1, 2022) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (April 10, 2022) 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 on April 25. The high latitude magnetometer at Andenes recorded quiet to unsettled levels.

Solar flux density measured at 20h UT on 2.8 GHz was 156.6 - increasing 7.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 93.88). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.3). Three hour interval K indices: 01121121 (planetary), 10132211 (Boulder), 00122232 (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 14 active regions using 2K resolution (SN: 256) and in 9 active regions using 1K resolution (SN: 147) SDO/HMI images.

Region 12993 [N20W43] decayed slowly, however, a small patch of emerging flux was observed in the trailing spots area. C1 flares: C1.3 @ 07:50, C1.6 @ 08:53, C1.4 @ 10:50, C1.2 @ 12:12, C1.2 @ 12:55, C1.2 @ 14:37 UT.
Region 12994 [N14W39] decayed slowly and was mostly quiet.
Region 12995 [N14W11] decayed slowly and quietly.
Region 12996 [N26E05] developed slowly and quietly.
Region 12997 [N12E38] was quiet and stable.
Region 12998 [S20E50] decayed slowly and quietly. Note that SWPC has assigned a new number (12999) to the region due to the faulty initial location of AR 12998. For data consistency the original number is used in this report.

Spotted regions not observed (or interpreted differently) by SWPC:
S7510 [N25E22] was quiet and stable.
S7513 [S20W21] reemerged with tiny spots.
S7515 [S22W02] was quiet and stable.
New region S7518 [S10E73] rotated into view with a tiny spot.
New region S7519 [S17E82] rotated into view with a single spot.
New region S7520 [S31E85] rotated partly into view with a single spot. C1 flares: C1.7 @ 06:28, C1.4 @ 10:24 UT.
New region S7521 [S30E38] was observed with a tiny spot in an old plage area.
New region S7522 [S17W38] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
M1.2 02:01 N22W26 12993 GOES16 LDE. An impulsive flare in AR 12995 was observed at the peak of this event
M1.1 04:02   12993 GOES16  
C4.6 08:53 N17W32 12994 GOES16 Flare occurred between AR 12993 and 12994
C3.0 16:18 N12W28 12994 GOES16  
C6.8 17:35   S7520 GOES16 CME
C4.8 21:10   12993 GOES16 LDE

Coronal mass ejections (CMEs)

April 23-25: No obviously Earth directed CMEs were observed in available LASCO imagery.

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 southern hemisphere coronal hole (CH1076) will be Earth facing on April 26-27.

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 fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

Quiet conditions are likely on April 25-27.

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
12991 2022.04.13
2022.04.14
      S23W77         location: S22W75
12993 2022.04.16
2022.04.16
7 19 10 N19W45 0200 CAO FAO  

beta-gamma

location: N20W43

12994 2022.04.16
2022.04.16
12 33 18 N14W39 0670 EKO EKO

beta-gamma

area: 0770

S7505 2022.04.17       S14W56          
12995 2022.04.18
2022.04.19
4 18 5 N13W09 0210 HSX CHO

location: N14W11

12996 2022.04.19
2022.04.20
5 14 10 N24E03 0030 CRO DRI location: N26E05

area: 0060

S7510 2022.04.21   1 1 N25E22 0003   AXX  
12997 2022.04.22
2022.04.23
5 16 8 N11E34 0030 CRO ERO

location: N12E38

S7512 2022.04.22       N38W15            
S7513 2022.04.22   3   S20W21 0005   BXO    
S7514 2022.04.22       S15W17            
S7515 2022.04.22   2   S22W02 0004   BXO  
12998 2022.04.23
2022.04.23
  5 3 S19W15 0230   HAX SWPC location way off

location: S20E50

12999 2022.04.25 1     S20E49 0180 HAX       SWPC renumber of AR 12998
S7517 2022.04.24       S18W11            
S7518 2022.04.25   1   S10E73 0001   AXX    
S7519 2022.04.25   1 1 S17E82 0030   HRX    
S7520 2022.04.25   1 1 S31E85 0100   HSX    
S7521 2022.04.25   1   S30E38 0001   AXX    
S7522 2022.04.25   1   S17W38 0002   AXX    
Total spot count: 34 156 57  
Sunspot number: 94 256 147  (total spot count + 10 * number of spotted regions)
Weighted SN: 65 200 101  (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): 103 141 118  

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 (solar max) 7.88
2017.09 91.3 92.3 43.6 18.2 (-1.3) 18.22
(cycle 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
2020.08 71.6 73.4 7.5 9.5 (+0.5) 5.68
2020.09 70.7 71.4 0.7 10.5 (+1.0) 8.59
2020.10 74.6 74.2 14.6 11.9 (+1.4) 6.13
2020.11 89.9 88.0 34.5 13.6 (+1.7) 4.77
2020.12 86.9 84.2 23.1 15.3 (+1.7) 4.72
2021.01 76.0 73.6 10.4 17.3 (+2.0) 4.39
2021.02 74.3 72.4 8.2 19.0 (+1.7) 9.50
2021.03 76.0 75.2 17.2 21.7 (+2.7) 10.17
2021.04 75.9 76.4 24.5 24.8 (+3.1) 8.40
2021.05 75.3 77.1 21.2 25.8 (+1.0) 6.50
2021.06 79.4 81.8 25.0 27.7 (+1.9) 5.52
2021.07 81.0 83.6 34.3 31.4 (+3.7) 5.51
2021.08 77.7 79.7 22.0 35.3 (+3.9) 6.19
2021.09 87.0 88.2 51.3 40.0 (+4.7) 6.33
2021.10 88.9 88.3 38.1 (44.9 projected, +4.9) 7.38
2021.11 86.2 84.4 35.0 (50.5 projected, +5.6) 9.83
2021.12 103.0 99.8 67.6 (56.4 projected, +5.9) 6.40
2022.01 103.8 100.5 54.0 (60.0 projected, +3.6) 8.92
2022.02 109.1 106.5 59.7 (64.8 projected, +4.8) 10.46
2022.03 117.0 115.8 78.3 (70.2 projected, +5.4) 10.20
2022.04 130.3 (1)   60.1 (2A) / 72.2 (2B) / 97.8 (2C) (75.4 projected, +5.2) (11.9)
2022.05       (81.8 projected, +6.4)  
2022.06       (87.7 projected, +5.9)  
2022.07       (94.9 projected, +7.2)  
2022.08       (101.6 projected, +6.7)  
2022.09       (106.6 projected, +5.0)  

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: SIDC-SILSO.

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.