Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 16, 2023 at 05:05 UT. There will be no update on May 17. Reports covering May 16 and 17 will be posted on May 18.

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, 2023)
Solar cycle Solar cycles 23-25 (May 1, 2023) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (May 1, 2023) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (July 1, 2020) POES auroral activity level [October 2009 - December 2012]
  Comparison of cycles 21-25 (May 1, 2023) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (May 1, 2023) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (April 5, 2023) 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 15 under the influence of weak effects from CH1146/CH1147. Solar wind speed at SOHO ranged between 454 and 511 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 134.5 - decreasing 18.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 141.00. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.9). Three hour interval K indices: 10001131 (planetary), 10113332 (Boulder), 20012252 (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: 234) and in 9 active regions using 1K resolution (SN: 159) SDO/HMI images.

Region 13301 [N13W10] decayed slowly and quietly.
Region 13302 [N18W03] was quiet and stable.
Region 13303 [S12W22] was quiet and stable.
Region 13304 [N20W35] decayed slowly and quietly.
Region 13305 [N09W00] developed slowly and could produce a minor M class flare. C1 flares: C1.0 @ 23:08 UT
Region 13306 [S19W48] decayed slowly and was mostly quiet. C1 flares: C1.8 @ 14:56 UT
New region 13307 [S09E33] emerged on May 14 and was numbered by SWPC the next day.

Spotted regions not observed (or interpreted differently) by SWPC:
S8549 [S21W21] was quiet and stable.
S8561 [N11E15] was quiet and stable.
New region S8566 [N21E41] emerged with tiny spots.

A C1.7 flare was recorded at 07:28 UT from AR 13297 behind the NW limb.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.4 00:51   13306 GOES16  
C2.6 01:06 behind southeast limb   GOES16  
C2.9 08:10 behind southeast limb   GOES16 very long duration event from a source 1-2 days behind the limb

Coronal mass ejections (CMEs)

May 13-15: No obviously Earth directed CMEs were observed.

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 trans equatorial coronal hole (CH1148) will likely become Earth facing on May 16-17.

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

Mostly quiet geomagnetic conditions are expected on May 16-18. On May 19-20 effects from CH1148 could cause quiet to minor storm conditions.

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
13299 2023.05.03
2023.05.04
      S08W81          

location: S07W78

13300 2023.05.06
2023.05.09
      N09W81          

 

13303 2023.05.07
2023.05.09
  5 3 S10W27 0012   AXX location: S12W22
13301 2023.05.08
2023.05.09
4 20 9 N14W14 0100 HAX CAO

location: N13W10

13304 2023.05.08
2023.05.11
3 9 4 N22W33 0010 BXO DRO location: N20W35

area: 0017

13302 2023.05.08
2023.05.09
5 19 9 N19W09 0090 DSO CSO area: 0130

location: N18W03

S8549 2023.05.09   7 2 S21W21 0014   BXO  
S8551 2023.05.10       N13W32            
13306 2023.05.10
2023.05.14
5 10 6 S18W50 0010 BXO BXO location: S19W48

area: 0020

S8553 2023.05.10       N26W49            
13305 2023.05.12 24 50 30 N10W03 0110 DAI DAI

location: N09E11

area: 0280

S8555 2023.05.12       S23W32            
S8556 2023.05.12       N13W46          
S8557 2023.05.13       N25W36            
S8558 2023.05.13       S37E19            
S8559 2023.05.14       N27W37          
S8560 2023.05.14       S28E11          
S8561 2023.05.14   5 1 N11E15 0010   BXO  
13307 2023.05.14
2023.05.15
2 6 5 S09E36 0010 BXO DRO area: 0020

location: S09E33

S8564 2023.05.14       S22W33          
S8565 2023.05.14       S22E22          
S8566 2023.05.15   3   N21E41 0004   BXO    
Total spot count: 43 134 69  
Sunspot number: 103 234 159  (total spot count + 10 * number of spotted regions)
Weighted SN: 58 155 90  (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): 113 129 127  

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 (SC24 solar max) 7.88
2017.09 91.3 92.3 43.6 18.2 (-1.3) 18.22
(SC24 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
2021.09 87.0 88.2 51.3 40.2 (+4.8) 6.33
2021.10 88.9 88.3 37.4 45.2 (+5.0) 7.38
2021.11 86.2 84.4 34.8 50.8 (+5.6) 9.83
2021.12 103.0 99.8 67.5 55.9 (+5.1) 6.40
2022.01 103.8 100.5 55.3 60.1 (+4.2) 8.92
2022.02 109.1 106.5 60.9 64.7 (+4.6) 10.46
2022.03 117.0 115.8 78.6 68.7 (+4.0) 10.20
2022.04 130.8 131.7 84.0 73.0 (+4.3) 11.79
2022.05 133.8 136.8 96.5 77.4 (+4.4) 7.48
2022.06 116.1 119.8 70.3 81.1 (+3.7) 8.20
2022.07 125.4 129.5 91.4 86.7 (+5.6) 9.51
2022.08 114.2 117.1 74.6 92.5 (+5.8) 10.92
2022.09 135.1 136.5 96.0 96.4 (+3.9) 12.18
2022.10 133.5 132.7 95.5 98.7 (+2.3) 11.16
2022.11 123.4 120.7 80.5 (100.4 projected, +1.7) 9.33
2022.12 147.9 143.4 112.8 (104.1 projected, +3.7) 10.99
2023.01 182.4 176.6 143.6 (110.1 projected, +6.0) 8.73
2023.02 167.2 163.2 110.9 (115.2 projected, +5.1) 14.48
(current
SC25 peak)
2023.03 157.2 155.6 122.6 (118.3 projected, +3.1) 14.42
2023.04 145.4 146.4 96.4 (123.7 projected, +5.4) 13.40
2023.05 156.0 (1)   58.5 (2A) / 121.0 (2B) / 151.1 (2C) (129.3 projected, +5.6) (11.4)
2023.06       (132.5 projected, +3.2)  
2023.07       (132.0 projected, -0.5)  
2023.08       (133.0 projected, +1.0)  
2023.09       (136.4 projected, +3.4)  
2023.10       (138.3 projected, +1.9)  
2023.11       (141.4 projected, +3.1)  
2023.12       (142.5 projected max SC25)  

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.