Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 3, 2022 at 07:45 UT. Minor update added at 13:40 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 (May 1, 2022)
Solar cycle Solar cycles 23-25 (May 1, 2022) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (May 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 (May 1, 2022) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (May 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 May 2. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 111.9 - decreasing 10.5 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 94.88). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 31100121 (planetary), 22111221 (Boulder), 51001243 (Andenes).

The background x-ray flux is at the class B7 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 180) and in 9 active regions using 1K resolution (SN: 134) SDO/HMI images.

Region 12997 [N12W58] was quiet and stable.
Region 12998 [S20W40] was quiet and stable. Note that SWPC 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.
Region 13000 [S17W08] was quiet and stable.
Region 13001 [S32W00] was quiet and stable.
New region 13004 [S16E12] was first observed with spots on April 27. New flux emerged on May 2 (when it was numbered by SWPC) and the region quickly became the most spot rich on the visible disk.
New region 13005 [N20E06] emerged with a tiny spot on May 1 and developed slowly on May 2 when the region was numbered by SWPC.

Spotted regions not observed (or interpreted differently) by SWPC:
S7534 [N18W09] was quiet and stable.
New region S7538 [S19E40] emerged with several spots.
New region S7539 [S27E83] rotated partly into view with small spots. C1 flares: C1.2 @ 18:24 UT. This region or another trailing region may be capable of M class flaring.
New region S7540 [S13E82] rotated into view with a tiny spot.

AR 12994 behind the northwest limb was the source of a C1.2 flare at 02:51 UT

Minor update added at 13:40 UT: Old region 12992 at the southeast limb was the source of an X1.1 flare at 13:25 UT on May 3. Further major flares are possible.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.2 19:20 southeast limb S7539? GOES16 LDE. Simultaneous event in AR 12994

Coronal mass ejections (CMEs)

April 30 - May 2: 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]

No obvious coronal holes are currently in or near Earth facing locations.

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 May 3-5.

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
12997 2022.04.22
2022.04.23
3 6 3 N12W58 0010 BXO CRO  
12998 2022.04.23
2022.04.23
  10 3   0140   CSO

location: S20W40

12999 2022.04.25 2     S19W41 0070 HSX       SWPC renumber of AR 12998
S7518 2022.04.25       S11W21          
13000 2022.04.25
2022.04.26
  5 1 S17W10 0008   AXX location: S17W08
13001 2022.04.25
2022.04.26
2 9 5 S32E01 0110 HSX CSO location: S32W00
S7521 2022.04.25       S28W55          
13002 2022.04.26
2022.04.28
      N13W28            
S7525 2022.04.26       N31E01            
S7526 2022.04.26       S17W18            
S7527 2022.04.26       N25W31            
13004 2022.04.27
2022.05.02
9 30 20 S16E12 0030 BXO DRI area: 0120
S7530 2022.04.27       S13W53            
13003 2022.04.28
2022.04.29
      S23E08          

location: S23E13

S7534 2022.04.30   5 3 N18W09 0010   BXO  
13005 2022.05.01
2022.05.02
3 7 5 N20E05 0020 BXO CRO area: 0030
S7537 2022.05.02       S17E31          
S7538 2022.05.02   5 3 S19E40 0030   DRO    
S7539 2022.05.02   2 1 S27E83 0010   HRX    
S7540 2022.05.02   1   S13E82 0002   AXX    
Total spot count: 19 80 44  
Sunspot number: 69 180 134  (total spot count + 10 * number of spotted regions)
Weighted SN: 29 105 69  (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): 76 99 107  

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
 

2020.10

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 27.6 (+1.8) 5.52
2021.07 81.0 83.6 34.3 31.3 (+3.7) 5.51
2021.08 77.7 79.7 22.0 35.3 (+4.0) 6.19
2021.09 87.0 88.2 51.3 40.0 (+4.7) 6.33
2021.10 88.9 88.3 37.4 45.0 (+5.0) 7.38
2021.11 86.2 84.4 34.8 (50.0 projected, +5.0) 9.83
2021.12 103.0 99.8 67.5 (55.8 projected, +5.8) 6.40
2022.01 103.8 100.5 54.0 (60.3 projected, +4.5) 8.92
2022.02 109.1 106.5 59.7 (65.2 projected, +4.9) 10.46
2022.03 117.0 115.8 78.5 (70.7 projected, +5.5) 10.20
2022.04 130.8 131.7 84.1 (75.9 projected, +5.2) 12.0
2022.05 110.5 (1)   3.4 (2A) / 52.5 (2B) / 88.6 (2C) (82.3 projected, +6.4) (6.1)
2022.06       (88.2 projected, +5.9)  
2022.07       (95.4 projected, +7.2)  
2022.08       (102.1 projected, +6.7)  
2022.09       (107.1 projected, +5.0)  
2022.10       (110.3 projected, +3.2)  

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.