[Ips-dsgr] ASWFC Daily Report - 27 September 26 issued 2330 UT on 27 Sep 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Mon Sep 28 09:30:48 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/27 SEPTEMBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 27 SEPTEMBER AND FORECAST FOR 28 SEPTEMBER - 30 SEPTEMBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 27 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 27 Sep: 97/44
1B. SOLAR FORECAST
28 Sep 29 Sep 30 Sep
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 98/45 100/48 105/54
COMMENT: Solar flare activity on UT day 27-Sep was at the R0
level, with only low-level C-class flares observed. There are
currently five numbered sunspot regions visible on the solar
disk. Active region (AR) 4533 (S13W27, beta) has returned after
decaying on the 26-Sep, but remains on the precipice of decay.
ARs 4534, 4537 and 4538 have all rotated off disk. AR 4536 (N03W77,
alpha) will rotate of disk in the next 24 hours. AR4524 is due
to return on the 29-Sep, if it has not yet decayed. It was previously
responsible for low-level M-class flares. All other sunspot regions
are either stable or in decay. Solar flare activity is expected
to be at the R0 level over 28-30 Sep. Solar radiation storm conditions
were at the S0 level on the 27-Sep, with the solar proton flux
at background levels. S0 solar radiation storm conditions are
forecast over 28-30 Sep. No Earth-directed coronal mass ejections
(CMEs) were observed over the past UT day. The solar wind speed
on UT day 27-Sep has gradually decreased as coronal hole high
speed wind stream effects abate. Speeds ranged from 470 to 365
km/s, the latter being the current speed. The peak total interplanetary
magnetic field strength (IMF, Bt) was 5 nT. The north-south component
(Bz) ranged between -4 and +2 nT over the same period. Sustained
periods of weak southward IMF were observed over most of the
UT day. The solar wind speed is expected to continue its decline
over the 28-Sep, before stabilising at typical levels.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 27 Sep: G0
Estimated Indices 27 Sep : A K
Australian Region 3 21212000
Cocos Island 2 21111000
Darwin 4 22212001
Townsville 4 31112011
Learmonth 2 21112000
Alice Springs 2 21102000
Gingin 3 21212000
Canberra 3 21212000
Kennaook Cape Grim 3 22212000
Hobart 3 22212000
Estimated Antarctic Regional K Indices 27 Sep :
Casey 9 34322101
Mawson 15 53222124
Observed Regional daily pc3 Indices 27 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 16 (Quiet)
Canberra 15 (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 27 Sep : A
Fredericksburg 10
Planetary 10
Observed AFr/Ap Indices 26 Sep : A K
Fredericksburg 11
Planetary 13 3433 2123
2B. MAGNETIC FORECAST
Date Ap Conditions
28 Sep 9 G0
29 Sep 5 G0
30 Sep 5 G0
COMMENT: G0 geomagnetic conditions were observed in Australia.
One period of G1 geomagnetic conditions was observed in the Antarctic
region at Mawson. Planetary geomagnetic conditions were at G0.
G0 geomagnetic conditions are expected over 28-30 Sep.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
27 Sep Normal Normal-fair Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
28 Sep Normal Normal Normal
29 Sep Normal Normal Normal
30 Sep Normal Normal Normal
COMMENT: Global high-frequency (HF) radio propagation conditions
on the 27-Sep were degraded at mid to high latitude regions due
to geomagnetic activity from a coronal hole. Global HF conditions
at mid to high latitudes are expected to return to normal conditions
on the 28-Sep and remain so on 29-30 Sep.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
27 Sep 55
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Enhanced by 45% during local day.
Enhanced by 45% 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
28 Sep 60 Near predicted monthly values
29 Sep 65 Near predicted monthly values
30 Sep 65 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
region were near predicted monthly values over UT day 27-Sep.
Notable enhancements were seen at Niue. Canberra experienced
spread-F during local night. MUFs are forecast to be near predicted
monthly values over 28-30 Sep.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 26 Sep
Daily Proton Fluence >1 MeV: 2.7E+05
Daily Proton Fluence >10 MeV: 2.1E+04
Daily Electron Fluence >2 MeV: 3.90E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 6%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B3.9
Solar Wind Day Averaged Data for 26 Sep
Speed: 471 km/sec Density: 4.1 p/cc Temp: 138000 K Bz: -1 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
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