Solar Terrestrial Activity Report

Activity chart

Last major update issued on April 19, 2022 at 07:05 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 18, weakly under the influence of a high speed stream associated with CH1074. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 140.5 - increasing 34.6 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 92.30). The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.4). Three hour interval K indices: 12221231 (planetary), 12332331 (Boulder), 12321352 (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 8 active regions using 2K resolution (SN: 160) and in 7 active regions using 1K resolution (SN: 110) SDO/HMI images.

Region 12987 [S31W84] rotated partly out of view but could produce further M class flares while just behind the southwest limb. C1 flares: C1.6 @ 15:55 UT
Region 12989 [N19W07] reemerged with a tiny spot.
Region 12990 [N16W22] was quiet and stable.
Region 12991 [S24E14] decayed slowly and quietly.
Region 12993 [N20E49] decayed slightly in the easternmost spot section. There's polarity intermixing in the western and central parts of the region and a major flare is possible. C1 flares: C1.9 @ 06:25 UT
Region 12994 [N13E54] was significantly less active than during the previous days as the trailing penumbra delta disappeared. A weak magnetic delta formed in a small penumbra to the west of the large trailing penumbra. A major flare is possible.

Spotted regions not observed (or interpreted differently) by SWPC:
S7505 [S16E40] was quiet and stable.
New region S7506 [N12E84] rotated into view with a single large spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C5.9 00:36   12993 GOES16  
C5.2 00:56   12993 GOES16  
C2.8 01:38   12993 GOES16  
C2.7 02:37   12994 GOES16 simultaneous activity in AR 12993 and 12987
C8.5 03:19   12987 GOES16  
C7.3 04:03   12994 GOES16  
C2.9 04:49   12987 GOES16  
C2.0 05:45   12993 GOES16  
M1.3 07:48 N19E67 12993 GOES16 similar intensity simultaneous flare in AR 12987
C2.5 09:14   12993 GOES16  
M1.1 10:27   12993 GOES16  
C2.0 13:25   12993 GOES16  
C3.9 14:24   12993 GOES16  
M1.9 17:24   12987 GOES16  
C3.0 19:55   12993 GOES16  
C7.3 20:15   12993 GOES16  
C3.1 22:32   12987 GOES16  

Coronal mass ejections (CMEs)

April 16-18: 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 northern hemisphere coronal hole (CH1074) was Earth facing on April 14-15. Another northern hemisphere coronal hole (CH1075) will likely rotate 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 19 due to a high speed stream from CH1074 becoming quiet on April 20-22. 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
12987 2022.04.04
2022.04.07
  7 5 S31W100 0150   DAI location: S31W84

beta-gamma

12992 2022.04.16 3     S28W85 0300 DAO       the spots are at the location of AR 12987
12988 2022.04.10
2022.04.11
      N14W44          

location: N15W41

S7488 2022.04.10       S13W38            
12989 2022.04.12
2022.04.12
  1   N18W07 0002   AXX    
12991 2022.04.13
2022.04.14
1 9 3 S24E12 0050 HAX CAO  
12990 2022.04.13 6 11 4 N16W31 0030 BXO CRO location: N16W22
S7494 2022.04.14       S15W57            
S7495 2022.04.14       N05W09            
S7496 2022.04.14       S25W12          
S7497 2022.04.15       S12W53            
12993 2022.04.16
2022.04.16
12 28 14 N18E51 0560 DHI FKI

beta-gamma

location: N20E49

12994 2022.04.16
2022.04.16
7 18 9 N13E53 0450 EKO EKO area: 0820

beta-delta

S7502 2022.04.16       S22E12            
S7503 2022.04.16       S29W27            
S7504 2022.04.16       N19W30          
S7505 2022.04.17   5 4 S16E40 0015   BXO  
S7506 2022.04.18   1 1 N12E84 0300   HHX    
Total spot count: 29 80 40  
Sunspot number: 79 160 110  (total spot count + 10 * number of spotted regions)
Weighted SN: 59 123 83  (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): 87 88 88  

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
2022.04 118.0 (1)   37.1 (2A) / 61.8 (2B) / 86.4 (2C) (75.4 projected, +5.2) (13.6)
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.