[Ips-dsgr] ASWFC Daily Report - 20 October 25 issued 2330 UT on 20 Oct 2025 [SEC=OFFICIAL]

Tue Oct 21 10:30:49 AEDT 2025

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/20 OCTOBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 20 OCTOBER AND FORECAST FOR 21 OCTOBER - 23 OCTOBER
STATUS INDICATORS SOL:** YELLOW **   MAG:GREEN     ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 20 Oct:  R1

Flares    Max     Fadeout    Freq.  Sectors
  M1.0    0527UT  possible   lower  E. Asia/Aust.

Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Oct: 140/94

1B. SOLAR FORECAST
             21 Oct             22 Oct             23 Oct
Activity     R0-R1              R0-R1              R0-R1
Fadeouts     Possible           Possible           Possible
10.7cm/SSN   140/94             140/94             145/99

COMMENT: Solar activity on UT day 20-Oct was at the R1 level 
due to an M1.0 flare at 20/0527UT produced by AR4248 (N06W93, 
beta). There are currently eight numbered regions visible on 
the solar disk and three unnumbered regions. AR4257 (S10E40, 
beta) is the most magnetically complex region on the disk and 
is mostly stable. AR4261 (S07E69, beta) recently rotated over 
the eastern limb and appears to be growing. Two unnumbered regions 
are visible near S09W35 (beta) and N09E01 (beta), both of which 
have shown mild spot growth. A third unnumbered region recently 
rotated over eastern limb near N09E71 (alpha) and appears stable. 
All other sunspot regions are either stable or in decay. Solar 
activity is expected to be at R0-R1 levels over 21-23 Oct. S0 
solar proton conditions were observed on UT day 20-Oct. S0 solar 
proton conditions are expected over 21-23 Oct. Several CMEs were 
observed, but none are considered geoeffective. No associated 
CME was observed following the disappearing filament at 19/1540UT 
mentioned in yesterday's report. The solar wind speed on UT day 
20-Oct declined, ranging from 470 to 605 km/s and is currently 
near 560 km/s. The peak total interplanetary magnetic field strength 
(IMF, Bt) was 11 nT and the north-south IMF component (Bz) range 
was -5 to +8 nT. The solar wind speed is expected to remain elevated 
on 21-Oct, then decline over 22-23 Oct due to waning coronal 
hole high speed wind stream effects from an equatorial coronal 
hole.

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2A. MAGNETIC SUMMARY

Geomagnetic field for Australian Region 20 Oct: G0

Estimated Indices 20 Oct : A   K           
   Australian Region       6   23212112
      Cocos Island         4   22111111
      Darwin              10   33312123
      Townsville           8   33212122
      Learmonth            9   33312212
      Alice Springs        5   22202112
      Gingin               6   32211112
      Canberra             6   23201122
      Kennaook Cape Grim   7   23311112
      Hobart               7   23312112    

Estimated Antarctic Regional K Indices 20 Oct :
      Macquarie Island     7   23312111
      Casey               27   56532123
      Mawson              16   44423123

Observed Regional daily pc3 Indices 20 Oct : 
      Darwin               0   (Quiet)
      Townsville           0   (Quiet)
      Learmonth            4   (Quiet)
      Alice Springs        2   (Quiet)
      Gingin              85   (Minor storm)
      Canberra            67   (Active)
      Hobart              78   (Active)

Pc3 pulsations are high frequency (10-45 second period) variations 
of the Earths magnetic field. Daily pc3-indices are the daily sum 
of 20 minute pc3-indices for that station and have been shown to be
well correlated with rejection of high resolution aeromagnetic
survey flight-line data. 

NOTE: Indices may have been generated from data obtained in 
cooperation with the following organisations: Geoscience Australia, 
University of Newcastle Space Physics Group, Australian Government 
Antarctic Division and International Center for Space Weather 
Science and Education, Japan.

Estimated AFr/Ap Indices 20 Oct : A 
           Fredericksburg        10
           Planetary             11                         

Observed AFr/Ap Indices 19 Oct :  A   K
           Fredericksburg        11
           Planetary             18   5323 3333     

2B. MAGNETIC FORECAST 
Date      Ap    Conditions
21 Oct     8    G0
22 Oct     5    G0
23 Oct     6    G0

COMMENT: G0 geomagnetic conditions were observed in the Australian 
region on UT day 20-Oct. G1-G2 geomagnetic conditions were observed 
in the Antarctic region. G0 geomagnetic conditions are expected 
over 21-23 Oct.

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3A. GLOBAL HF PROPAGATION SUMMARY
	            Latitude Band
Date        Low            Middle         High 
20 Oct      Normal         Normal         Normal         

PCA Event : No event.

3B. GLOBAL HF PROPAGATION FORECAST
	            Latitude Band
Date        Low            Middle         High 
21 Oct      Normal         Normal         Normal-fair
22 Oct      Normal         Normal         Normal
23 Oct      Normal         Normal         Normal

COMMENT: HF radio propagation conditions on UT day 20-Oct were 
normal. Mostly normal HF conditions are expected over 21-23 Oct. 
Shortwave fadeouts are possible.

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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY

Date   T index
20 Oct    96

Observed Australian Regional MUFs
   Cocos Island Region:
      Near predicted monthly values during local day.
      Enhanced by 45% during local night.
   Niue Island Region:
      Near predicted monthly values.
   Northern Australian Region:
      Near predicted monthly values.
   Southern Australian Region:
      Near predicted monthly values.
   Antarctic Region (Casey/Davis/Mawson):
      Near predicted monthly values over the UT day.

Monthly T index:
Month  T index
Sep      109
Oct      89
Nov      89

4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date   T index  MUFs
21 Oct   100    Near predicted monthly values
22 Oct   100    Near predicted monthly values
23 Oct   100    Near predicted monthly values

COMMENT: Maximum usable frequencies (MUFs) in the Australian 
region on UT day 20-Oct were near predicted monthly values. Mild 
spread F was observed at Hobart during local night hours. MUFs 
are expected to be near predicted monthly values over 21-23 Oct. 
Shortwave fadeouts are possible.

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5. SPACE ENVIRONMENT SUMMARY

GOES satellite data for 19 Oct
       Daily Proton Fluence >1 MeV:   3.2E+05
       Daily Proton Fluence >10 MeV:  1.5E+04
       Daily Electron Fluence >2 MeV: 1.60E+07   (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
       X-ray background: C1.7

DSCOVR Satellite Solar Wind Day Averaged Data for 19 Oct
Speed: 529 km/sec  Density:    3.0 p/cc  Temp:   254000 K  Bz:   3 nT

(Courtesy Space Weather Prediction Center, Boulder USA)
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Australian Space Weather Forecasting Centre
Bureau of Meteorology
ASWFC at bom.gov.au
www.bom.gov.au | www.sws.bom.gov.au