Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 11, 2021 at 05:45 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 (October 3, 2021)
Solar cycle Solar cycles 23-25 (October 1, 2021) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (October 1, 2021) 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 (October 1, 2021) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (October 1, 2021) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (August 22, 2021) 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 minor storm on October 10. The high latitude magnetometer at Andenes recorded quiet to major storm conditions. A disturbance started after noon as what is likely a low speed stream associated with CH1035 arrived.

Solar flux density measured at 20h UT on 2.8 GHz was 84.5 - increasing 1.2 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 79.91). The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 10.8). Three hour interval K indices: 12123225 (planetary), 11113224 (Boulder), 10014436 (Andenes).

The background x-ray flux is at the class B1 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 3 active regions using 2K resolution (SN: 64) and in 3 active regions using 1K resolution (SN: 46) SDO/HMI images.

Region 12882 [N18E00] was quiet and in slow decay.
New region 12883 [N27W60] was first observed with spots on October 6 and was numbered by SWPC 4 days later. Slow development was observed during the day.
New region 12884 [S20W26] emerged on October 9 and received an SWPC region number the following day.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
C2.3 23:02 N32W90 12880 GOES16 behind the NW limb

Coronal mass ejections (CMEs)

October 8 and 10: No obviously Earth directed CMEs were observed in available LASCO imagery.
October 9: A nearly symmetrical full halo CME was observed after the M1.6 event in AR 12882. The CME will likely reach Earth on October 11 and cause unsettled to severe storm conditions lasting that day and October 12.

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 poorly defined trans equatorial coronal hole (CH1036) developed slowly on October 8 while rotating across the central meridian and could cause unsettled intervals on October 11-12 (the disturbance will likely not be noticed due to the much stronger CME related disturbance the same days).

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is very poor. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to severe storm conditions on October 11-12 due to CME effects and quiet to unsettled on October 13.

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 red colored.

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
12882 2021.10.03
2021.10.03
4 21 8 N18W14 0260 DHO DHO beta-gamma

area: 0370

location: N17W12

S7117 2021.10.04       N08W39            
S7118 2021.10.04       N23W07            
S7119 2021.10.06       S35W45            
S7120 2021.10.06       N24W17            
12883 2021.10.06
2021.10.10
2 9 6 N27W60 0030 BXO BXO area: 0020
S7122 2021.10.06       S31E20            
S7123 2021.10.08       S36W11            
12884 2021.10.09
2021.10.10
2 4 2 S20W27 0010 BXO CRO area: 0020
Total spot count: 8 34 16  
Sunspot number: 38 64 46  (total spot count + 10 * number of spotted regions)
Weighted SN: 18 47 29  (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): 43 35 37  

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 (cycle 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
2020.04 69.5 70.0 5.4 3.6 (+0.6) 5.32
2020.05 69.0 70.6 0.2 5.6 (+2.0) 3.80
2020.06 69.5 71.7 5.8 7.9 (+2.3) 3.75
2020.07 69.5 71.8 6.3 9.0 (+1.1) 4.28
2020.08 71.6 73.4 7.6 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 8.3 19.1 (+1.8) 9.50
2021.03 76.0 75.2 17.3 21.8 (+2.7) 10.17
2021.04 75.9 76.4 24.5 (26.0 projected, +4.2) 8.40
2021.05 75.3 77.1 21.2 (28.7 projected, +2.7) 6.50
2021.06 79.4 81.8 25.3 (31.9 projected, +3.2) 5.52
2021.07 81.0 83.6 34.4 (36.5 projected, +4.6) 5.51
2021.08 77.7 79.7 22.4 (41.1 projected, +4.6) 6.19
2021.09 87.0 88.2 51.5 (46.8 projected, +5.7) 6.6
2021.10 85.7 (1)   8.0 (2A) / 24.7 (2B) / 44.1 (2C) (51.2 projected, +4.4) (6.2)
2021.11       (55.8 projected, +4.6)  
2021.12       (61.7 projected, +5.9)  
2022.01       (65.3 projected, +3.6)  
2022.02       (70.0 projected, +4.7)  
2022.03       (75.4 projected, +5.4)  

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.