[Ips-dsgr] ASWFC Daily Report - 18 September 26 issued 2330 UT on 18 Sep 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sat Sep 19 09:30:51 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 SEPTEMBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 SEPTEMBER AND FORECAST FOR 19 SEPTEMBER - 21 SEPTEMBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Sep: 96/43
1B. SOLAR FORECAST
19 Sep 20 Sep 21 Sep
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 95/41 95/41 95/41
COMMENT: Solar flare activity on UT day 18-Sep was at the R0
level, with no observed flares at the C-class level or higher.
The visible solar disk is currently spotless, with no active
regions. Solar flare activity is forecast to remain at the R0
level over 19-21 Sep due to the lack of notable active regions.
Solar radiation storm conditions were at the S0 level over 18-Sep,
with S0 conditions forecast over 19-21 Sep. No coronal mass ejections
(CMEs) were observed over the past 24 hours in available coronagraph
imagery. The solar wind speed declined over 18-Sep as the high
speed wind stream effects of a previous coronal hole continued
to wane. The solar wind speed began the day at 450-460 km/s,
and is currently at approximately 410 km/s. The interplanetary
magnetic field strength (IMF, Bt) was largely stable throughout
the UT day, peaking at 5 nT, with the north-south component (Bz)
ranging between -4 and +4 nT. The solar wind is expected to continue
to trend toward background values over 19-21 Sep.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Sep: G0
Estimated Indices 18 Sep : A K
Australian Region 2 12110002
Cocos Island 1 11110001
Darwin 2 12110002
Townsville 3 12111012
Learmonth 3 22110002
Alice Springs 2 11110002
Gingin 2 21110002
Canberra 2 11110002
Kennaook Cape Grim 2 12110001
Hobart 2 12110001
Estimated Antarctic Regional K Indices 18 Sep :
Casey 10 34331002
Mawson 16 33321154
Observed Regional daily pc3 Indices 18 Sep :
Darwin 2 (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 18 Sep : A
Fredericksburg 8
Planetary 8
Observed AFr/Ap Indices 17 Sep : A K
Fredericksburg 7
Planetary 9 3222 3222
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Sep 4 G0
20 Sep 4 G0
21 Sep 3 G0
COMMENT: Geomagnetic conditions in the Australian region were
at the G0 level over 18-Sep, with G0 conditions also observed
at the planetary level. Mostly G0 conditions were reported in
the Antarctic region, with a single G1 interval recorded at Mawson.
G0 conditions are forecast over 19-21 Sep.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Sep Normal Normal-fair Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Sep Normal Normal Normal
20 Sep Normal Normal Normal
21 Sep Normal Normal Normal
COMMENT: Global high-frequency (HF) radio propagation conditions
were normal-fair on 18-Sep, with some degradations observed in
northern hemisphere mid-latitude regions during local night hours.
Global propagation conditions are forecast to be mostly normal
over 19-21 Sep.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Sep 52
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Northern Australian Region:
Depressed by 15% during local day.
Near predicted monthly values during local night.
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
19 Sep 60 Near predicted monthly values
20 Sep 60 Near predicted monthly values
21 Sep 60 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
region on UT day 18-Sep were mostly near predicted monthly values,
with some daytime depressions observed early in the UT day across
the northern Australian region, particularly at Darwin and Townsville.
Strong spread-F was also observed at Hobart. MUFs are expected
to remain near predicted values over 19-21 Sep.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Sep
Daily Proton Fluence >1 MeV: 2.9E+05
Daily Proton Fluence >10 MeV: 2.0E+04
Daily Electron Fluence >2 MeV: 2.30E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 4%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B2.0
Solar Wind Day Averaged Data for 17 Sep
Speed: 474 km/sec Density: 3.3 p/cc Temp: 126000 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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