Solar Terrestrial Activity Report

Activity chart

Last major update issued on April 27, 2022 at 10:50 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 very quiet on April 26. The high latitude magnetometer at Andenes recorded quiet levels.

Solar flux density measured at 20h UT on 2.8 GHz was 148.9 - decreasing 2.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 94.07). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.0). Three hour interval K indices: 00101100 (planetary), 00112311 (Boulder), 00102100 (Andenes).

The background x-ray flux is at the class B8 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 18 active regions using 2K resolution (SN: 305) and in 12 active regions using 1K resolution (SN: 169) SDO/HMI images.

Region 12993 [N20W58] decayed further and was mostly quiet. C1 flares: C1.2 @ 20:54 UT
Region 12994 [N14W54] decayed slowly and was mostly quiet.
Region 12995 [N14W24] was mostly quiet and stable.
Region 12996 [N25W09] decayed slowly and quietly.
Region 12997 [N12E26] developed slowly and was quiet.
Region 12998 [S20E38] was quiet and stable. 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.
New region 13000 [S17E70] rotated into view on April 25 and was numbered the next day by SWPC.
New region 13001 [S31E74] rotated into view on April 25 and received its NOAA number the next day. C1 flares: C1.1 @ 19:10 UT

Spotted regions not observed (or interpreted differently) by SWPC:
S7510 [N25E09] was quiet and stable.
S7513 [S26W37] was quiet and stable.
S7515 [S19W13] was quiet and stable.
S7518 [S10E60] was quiet and stable.
S7521 [S28E22] was quiet and stable.
New region S7523 [S05W31] emerged with tiny spots.
New region S7524 [N14E57] emerged with a tiny spot.
New region S7525 [N31E79] rotated into view with a single small spot.
New region S7526 [S15E58] emerged with tiny spots.
New region S7527 [N25E47] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.2 08:28 N19W16 12995 GOES16 Simultaneous flare in AR 12991
C2.1 09:58 N21W48 12993 GOES16  
C2.8 11:18   12991 GOES16  
C2.9 12:44   13001 GOES16  
C3.2 13:03 N15W42 12994 GOES16  
C3.9 16:24   12991 GOES16  

Coronal mass ejections (CMEs)

April 24-26: 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) was 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 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
12993 2022.04.16
2022.04.16
9 8 3 N20W56 0230 CSO CAO

 

location: N20W58

12994 2022.04.16
2022.04.16
16 34 15 N16W54 0430 EKO EKI

beta-gamma

area: 0580

location: N14W57

12995 2022.04.18
2022.04.19
2 19 7 N14W24 0170 HSX CHO

 

12996 2022.04.19
2022.04.20
7 9 3 N25W11 0010 BXO CRO location: N25W09

area: 0030

S7510 2022.04.21   1 1 N25E09 0002   AXX  
12997 2022.04.22
2022.04.23
7 18 10 N12E22 0030 CRO ERO

location: N12E26

S7512 2022.04.22       N38W28            
S7513 2022.04.22   3   S26W37 0005   BXO  
S7514 2022.04.22       S15W30            
S7515 2022.04.22   3   S19W13 0003   AXX  
12998 2022.04.23
2022.04.23
  16 5 S19W29 0230   CSO SWPC location way off

location: S20E38

12999 2022.04.25 3     S20E37 0140 HAX       SWPC renumber of AR 12998
S7517 2022.04.24       S18W24            
S7518 2022.04.25   2   S10E60 0002   AXX  
13000 2022.04.25
2022.04.26
1 1 1 S16E71 0050 HSX HSX location: S17E70
13001 2022.04.25
2022.04.26
1 1 1 S29E68 0110 HSX HSX  
S7521 2022.04.25   2   S28E22 0002   AXX  
S7522 2022.04.25       S17W51          
S7523 2022.04.26   3   S05W31 0004   BXO    
S7524 2022.04.26   1 1 N14E57 0004   AXX    
S7525 2022.04.26   1 1 N31E79 0020   HRX    
S7526 2022.04.26   2 1 S15E58 0007   AXX    
S7527 2022.04.26   1   N25E47 0002   AXX    
Total spot count: 46 125 49  
Sunspot number: 126 305 169  (total spot count + 10 * number of spotted regions)
Weighted SN: 84 174 98  (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): 139 168 135  

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
2022.04 131.0 (1)   64.4 (2A) / 74.2 (2B) / 97.7 (2C) (75.4 projected, +5.2) (11.5)
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.