[Ips-dsgr] ASWFC Daily Report - 23 September 26 issued 2330 UT on 23 Sep 2026 [SEC=OFFICIAL]

Thu Sep 24 09:30:54 AEST 2026

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/23 SEPTEMBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 23 SEPTEMBER AND FORECAST FOR 24 SEPTEMBER - 26 SEPTEMBER
STATUS INDICATORS SOL:GREEN   MAG:** YELLOW **     ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 23 Sep:  R0

Flares: none.

Observed 10.7 cm flux/Equivalent Sunspot Number for 23 Sep: 121/73

1B. SOLAR FORECAST
             24 Sep             25 Sep             26 Sep
Activity     R0, chance R1      R0, chance R1      R0, chance R1
Fadeouts     None expected      None expected      None expected
10.7cm/SSN   120/72             120/72             118/70

COMMENT: Solar flare activity on UT day 23-Sep was at the R0 
level, with only low-level C-class flares observed. There are 
currently nine numbered sunspot regions visible on the solar 
disk. Active region (AR) 4534 (N10W47, beta) is currently the 
most magnetically complex region however has exhibited decay 
over the past UT day. All other sunspot regions are either stable 
or in decay. Solar flare activity is expected to be at the R0 
level over 24-26 Sep, with a chance of R1. Solar radiation storm 
conditions were at the S0 level on 23-Sep, with the solar proton 
flux at background levels. S0 solar radiation storm conditions 
are forecast over 24-26 Sep. No Earth-directed coronal mass ejections 
(CMEs) were observed over the past UT day. The solar wind speed 
on UT day 23-Sep slightly increased, ranging from 275 to 315 
km/s, and is currently near 310 km/s. The peak total interplanetary 
magnetic field strength (IMF, Bt) was 14 nT. The north-south 
component (Bz) ranged between -3 and +9 nT over the same period. 
The solar wind speed is expected to increase over 24-Sep and 
remain elevated over 25-26 Sep due to coronal hole high speed 
wind stream effects from a southern hemisphere coronal hole.

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2A. MAGNETIC SUMMARY

Geomagnetic field for Australian Region 23 Sep: G0

Estimated Indices 23 Sep : A   K           
   Australian Region       2   11000012
      Cocos Island         2   11100012
      Darwin               4   11101023
      Townsville           3   11001122
      Learmonth            5   2-200123
      Alice Springs        1   00000022
      Gingin               1   10000011
      Canberra             1   01000012
      Kennaook Cape Grim   2   11000012
      Hobart               1   11000011    

Estimated Antarctic Regional K Indices 23 Sep :
      Casey                4   23220000
      Mawson               0   11000000

Observed Regional daily pc3 Indices 23 Sep : 
      Darwin               0   (Quiet)
      Townsville           0   (Quiet)
      Learmonth            0   (Quiet)
      Alice Springs        0   (Quiet)
      Gingin               0   (Quiet)
      Canberra             0   (Quiet)

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 23 Sep : A 
           Fredericksburg         4
           Planetary              7                         

Observed AFr/Ap Indices 22 Sep :  A   K
           Fredericksburg         2
           Planetary              3   2100 0111     

2B. MAGNETIC FORECAST 
Date      Ap    Conditions
24 Sep    24    G1
25 Sep     8    G0
26 Sep     8    G0

COMMENT: ASWFC Geomagnetic Warning 57 was issued on 23 September 
and is current for 23-24 Sep. G0 geomagnetic conditions were 
observed in the Australian and Antarctic regions on UT day 23-Sep, 
with G0 geomagnetic conditions also recorded at the planetary 
scale. G1 planetary geomagnetic conditions are forecast on 24-Sep 
due to coronal hole high speed wind stream effects and the solar 
equinox. The solar equinox period can heighten geomagnetic activity. 
G0 geomagnetic conditions are expected over 25-26 Sep.

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3A. GLOBAL HF PROPAGATION SUMMARY
	            Latitude Band
Date        Low            Middle         High 
23 Sep      Normal         Normal         Normal-fair    

PCA Event : No event.

3B. GLOBAL HF PROPAGATION FORECAST
	            Latitude Band
Date        Low            Middle         High 
24 Sep      Normal         Normal-fair    Fair
25 Sep      Normal         Normal         Normal-fair
26 Sep      Normal         Normal         Normal-fair

COMMENT: Global high-frequency (HF) radio propagation conditions 
on the 23-Sep were mostly normal, with some normal-fair conditions 
observed in high latitude regions. Global HF conditions are expected 
to be normal to fair on 24-Sep due to forecast geomagnetic activity. 
Conditions are expected to return to normal over 25-26 Sep.

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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY

Date   T index
23 Sep    68

Observed Australian Regional MUFs
   Cocos Island Region:
      No data available during local day.
      No data available during local night.
   Niue Island Region:
      Enhanced by 35% during local day.
      Enhanced by 20% during local night.
   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
Aug      66
Sep      62
Oct      60

4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date   T index  MUFs
24 Sep    45    Near predicted monthly values
25 Sep    60    Near predicted monthly values
26 Sep    70    Near predicted monthly values

COMMENT: Maximum Usable Frequencies (MUFs) in the Australian 
region were mostly near predicted monthly values over UT day 
23-Sep, with enhancements of 20-35% observed at Niue. Spread-F 
was observed at Hobart during local night hours. MUFs are forecast 
to be near predicted monthly values over 24-26 Sep. While depressions 
are expected due to anticipated geomagnetic activity, current 
MUFs are already mildly elevated above predicted monthly values.

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5. SPACE ENVIRONMENT SUMMARY

GOES satellite data for 22 Sep
       Daily Proton Fluence >1 MeV:   3.0E+05
       Daily Proton Fluence >10 MeV:  2.1E+04
       Daily Electron Fluence >2 MeV: 2.90E+07   (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 5%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
       X-ray background: B4.0

Solar Wind Day Averaged Data for 22 Sep
Speed: 305 km/sec  Density:    1.9 p/cc  Temp:    46900 K  Bz:   2 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