Solar Terrestrial Activity Report

Activity chart

Last major update issued on April 22, 2022 at 11:30 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 to unsettled on April 21. The high latitude magnetometer at Andenes recorded quiet to active levels.

Solar flux density measured at 20h UT on 2.8 GHz was 164.4 - increasing 52.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 92.99). The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.9). Three hour interval K indices: 33323221 (planetary), 32333221 (Boulder), 43333232 (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 9 active regions using 2K resolution (SN: 239) and in 8 active regions using 1K resolution (SN: 147) SDO/HMI images.

Region 12991 [S22W20] developed as new flux emerged in the northern part of the region.
Region 12993 [N20E09] became more complex as the opposite polarity umbrae to the north of the largest penumbra are merging with that penumbra. Further major flares are possible.
Region 12994 [N13E15] displayed only minor changes and still has major flare potential. C1 flares: C1.9 at 18:55 UT
Region 12995 [N13E42] was quiet and stable.
Region 12996 [N23E54] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC:
S7496 [S27W48] reemerged with a tiny spot.

S7505 [S15W01] was quiet and stable.
New region S7509 [S21W43] emerged with a few tiny spots.
New region S7510 [N25E74] rotated into view with tiny spots.

AR 12987 from behind the southwest limb was the source of a C1.6 flare at 22:45 UT and an associated fast and weak type II radio sweep.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.2 00:25   12993 GOES16  
M9.6/1N 01:59 N25E23 12993 GOES16 narrow CME, weak type IV and moderate type II radio sweeps
C4.6 03:48   12994 GOES16  
C5.2 05:30   12993 GOES16  
C3.0 07:23   12994 GOES16  
C3.0 09:46 behind SW limb 12987 GOES16  
C5.4/1F 12:55   12994 GOES16  
C3.1 17:27   12993 GOES16  
C7.0 21:04   12994 GOES16  

Coronal mass ejections (CMEs)

April 19-20: No obviously Earth directed CMEs were observed in available LASCO imagery.
April 21: The CME observed after the M9.6 flare in AR 12993 early in the day had a narrow core. LASCO imagery is not conclusive with regards to faint, slow moving components of the CME in other directions than towards the northeast. If there is any impact from this CME it will likely not be very significant.

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 northern hemisphere coronal hole (CH1075) rotated across the central meridian on April 20-21.

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.

Forecast

Quiet to unsettled conditions are likely on April 22. Quiet to minor storm conditions are possible on April 23-24 due to effects from CH1075.

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
12988 2022.04.10
2022.04.11
      N14W86          

location: N15W80

12989 2022.04.12
2022.04.12
      N18W49         location: N20W41
12991 2022.04.13
2022.04.14
6 23 6 S21W20 0030 CRO DRO location: S22W20
12990 2022.04.13       N16W73           location: N16W60
S7495 2022.04.14       N05W48            
S7496 2022.04.14   1   S27W48 0001   AXX    
12993 2022.04.16
2022.04.16
35 56 30 N22E08 0600 FKC EKC

 

beta-gamma-delta

location: N20E09

12994 2022.04.16
2022.04.16
22 42 22 N15E15 0770 EKC EKI

location: N13E15

beta-gamma

S7502 2022.04.16       S22W27            
S7505 2022.04.17   5 1 S15W01 0010   BXO  
12995 2022.04.18
2022.04.19
3 9 3 N16E44 0260 CHO CHO area: 0340

location: N13E42

12996 2022.04.19
2022.04.20
3 6 3 N25E56 0100 CAO CAO location: N23E54
S7508 2022.04.20       N06W38         likely SC 24 group
S7509 2022.04.21   4 1 S21W43 0008   CRO    
S7510 2022.04.21   3 1 N25E74 0007   BXO    
Total spot count: 69 149 67  
Sunspot number: 119 239 147  (total spot count + 10 * number of spotted regions)
Weighted SN: 107 190 108  (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): 131 131 117  

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
2022.04 124.8 (1)   46.0 (2A) / 65.7 (2B) / 90.6 (2C) (75.4 projected, +5.2) (12.8)
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.