Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 19, 2020 at 05:30 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 (October 5, 2020)
Solar cycle Solar cycles 23-25 (October 2, 2020) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (October 2, 2020) 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 2, 2020) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (October 2, 2020) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (July 6, 2020) Cycle 25 spots (final update December 25, 2019)
  Solar cycles 24-25 using 365d smoothing (*) Recent research
    Current research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing

Recent activity

The geomagnetic field was very quiet on October 18. The high latitude magnetometer at Andenes recorded quiet to unsettled conditions.

Solar flux at 20h UT on 2.8 GHz was 75.9 - increasing 4.6 over the previous solar rotation. (Centered 1 year average SF at 1 AU: Minimum of 69.13 on November 17, 2019. Current: 70.43). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.8). Three hour interval K indices: 00000011 (planetary), 11001111 (Boulder), 20000013 (Andenes).

The background x-ray flux is at the class A5 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 5 active regions using 2K resolution (SN: 71) and in 4 active regions using 1K resolution (SN: 49) SDO/HMI images.

Region 12776 [S13E11] was mostly quiet and stable with B flare activity observed early in the day. The region has minor polarity intermixing.
New region 12777 [S23W78] emerged near the southwest limb and could produce C flares while at the limb. The region was initially numbered S6580.

Spotted regions not observed (or interpreted differently) by SWPC:
S6579 [S17E18] decayed slowly and quietly after noon.
New region S6581 [N05W33] emerged with tiny spots as a cycle 24 region.
New region S6582 [N23W49] emerged with a single spot.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
           

Coronal mass ejections (CMEs)

October 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 coronal hole (CH975) in the southern hemisphere was Earth facing on October 16-17. A recurrent northern hemisphere coronal hole (CH976) will likely rotate into an Earth facing position on October 19-23.

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 good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on October 19 becoming quiet to unsettled on October 20-23 due to effects from CH975 and later CH976.

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 numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. 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.

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 Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
S6573 2020.10.12       S22W50            
12776 2020.10.13
2020.10.14
6 10 5 S14E13 0100 CSO CAO area: 0130

location: S13E11

S6577 2020.10.15       N07W43            
S6578 2020.10.16       N25W22            
S6579 2020.10.17   5 2 S17E18 0009   BXO  
12777 2020.10.18
2020.10.18
2 3 1 S24W77 0010 BXO AXX   S6580
S6581 2020.10.18   2   N05W33 0002   BXO    
S6582 2020.10.18   1 1 N23W49 0004   AXX    
Total spot count: 8 21 9  
Sunspot number: 28 71 49  (total spot count + 10 * number of spotted regions)
Weighted SN: 13 26 14  (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): 31 39 39 k * (sunspot number)
As of May 7, 2016: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.80 for MSN 1K (MSN=Magnetic Sunspot Number)

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)
2019.04 72.4 72.9 9.1 4.3 (-0.3) 6.06
2019.05 71.3 72.8 9.9 3.9 (-0.4) 6.98
2019.06 68.1 70.3 1.2 3.7 (-0.2) 4.26
2019.07 67.1 69.3 0.9 3.5 (-0.2) 5.36
2019.08 67.0 68.7 0.5 3.4 (-0.1) 6.79
2019.09 67.9 68.7 1.1 3.1 (-0.3) 9.81
2019.10 67.4 67.0 0.4 2.6 (-0.5) 7.53
2019.11 70.2 68.7 0.5 2.0 (-0.6)
(November 17, 2019 is
the solar minimum using 365d
smoothing for 1 AU solar flux,
NOAA SN and both
of STAR 1K and 2K SN)
4.19
2019.12 70.8 68.6 1.6 1.8 (-0.2)
(ISN 13 months smoothed
solar minimum)
3.22
2020.01 72.2 69.9 6.4 2.2 (+0.4) 4.39
2020.02 71.0 69.3 0.4 2.8 (+0.6) 6.16
2020.03 70.2 69.5 1.5 3.0 (+0.2) 5.63
2020.04 69.5 70.0 5.4 (3.3 projected, +0.3) 5.32
2020.05 69.0 70.6 0.2 (4.1 projected, +0.8) 3.80
2020.06 69.5 71.7 5.8 (5.3 projected, +1.2) 3.75
2020.07 69.5 71.8 6.3 (6.3 projected, +1.0) 4.28
2020.08 71.6 73.4 7.6 (7.6 projected, +1.3) 5.68
2020.09 70.7 71.4 0.7 (9.6 projected, +2.0) 8.59
2020.10 (72.9)   5.6 (2A) / 9.7 (2B) / 10.6 (2C) (11.1 projected, +1.5) (3.7)
2020.11       (12.5 projected, +1.4)  
2020.12       (14.5 projected, +2.0)  
2021.01       (16.6 projected, +2.1)  
2021.02       (18.6 projected, +2.0)  
2021.03       (20.8 projected, +2.2)  

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
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 transition

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.