[Ips-dsgr] ASWFC Daily Report - 18 September 25 issued 2330 UT on 18 Sep 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Fri Sep 19 09:30:46 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 SEPTEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 SEPTEMBER AND FORECAST FOR 19 SEPTEMBER - 21 SEPTEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
-----------------------------------------------------------
1A. SOLAR SUMMARY
Activity 18 Sep: Low
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Sep: 150/105
1B. SOLAR FORECAST
19 Sep 20 Sep 21 Sep
Activity Low to moderate Low to moderate Low to moderate
Fadeouts Possible Possible Possible
10.7cm/SSN 150/105 150/105 150/105
COMMENT: Solar activity on UT day 18-Sep was R0, with no solar
flares. There are currently six numbered sunspot regions on the
solar disk, AR4216 (N11W11, beta gamma) is the most magnetically
complex region on the disk but is showing decay. AR4220 (S18W12,gamma)
is showing growth and an increasing magnetic complexity. All
other regions are either stable or in decay. Solar activity is
expected to be R0 over 19-21 Sep. No Earth-directed CMEs have
been observed over the UT day 18 Sep however and event on 17-Sep
with an uncertain source was further analysed to potentially
arrive at Earth late on 21-Sep. This event is slow and not likely
to be significantly geoeffective. S0 solar radiation storm conditions
were observed on UT day 18-Sep. S0 solar radiation storm conditions
are expected over 19-21 Sep. The solar wind on UT day 18-Sep
has been in a slow steady decline. Currently the solar wind is
481 km/s. The peak total interplanetary field strength (IMF,
Bt) was 4 nT and the north-south IMF component range (Bz) was
+4 to -3 nT. The solar wind is expected to be mostly undisturbed
over 19-21 Sep.
Region 4197 (S18) which previously produced M-flare(s) is due
to return around 19 Sep.
-----------------------------------------------------------
2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Sep: G0
Estimated Indices 18 Sep : A K
Australian Region 6 21222301
Cocos Island 3 21121200
Darwin 7 22222302
Townsville 5 22222201
Learmonth 7 22223301
Alice Springs 5 21222201
Gingin 7 21232301
Canberra 4 11122300
Kennaook Cape Grim 6 11232301
Hobart 6 11232301
Estimated Antarctic Regional K Indices 18 Sep :
Macquarie Island 9 11153200
Casey 14 34432311
Mawson 15 33333243
Observed Regional daily pc3 Indices 18 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 14 (Quiet)
Canberra 23 (Quiet to unsettled)
Hobart 16 (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 7
Planetary 7
Observed AFr/Ap Indices 17 Sep : A K
Fredericksburg 10
Planetary 12 2333 2123
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Sep 8 G0
20 Sep 6 G0
21 Sep 5 G0
COMMENT: G0 geomagnetic conditions were observed in the Australian
and Antarctic regions on UT day 18-Sep. G0 geomagnetic conditions
are expected over 19-21 Sep.
-----------------------------------------------------------
3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Sep Normal Normal Normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Sep Normal Normal Normal-fair
20 Sep Normal Normal Normal
21 Sep Normal Normal Normal
COMMENT: HF radio propagation conditions on UT day 18-Sep were
mostly normal. HF radio propagation conditions are expected to
be mostly normal over 19-21 Sep.
-----------------------------------------------------------
4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Sep 101
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.
Enhanced by 35% 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 96
Sep 92
Oct 90
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
19 Sep 100 Near predicted monthly values
20 Sep 100 Near predicted monthly values
21 Sep 95 Near predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 18-Sep were mostly near predicted values to
35% enhanced. Spread-F was observed in Perth and during local
night hours. MUFs are expected to be near predicted values over
19-21 Sep.
-----------------------------------------------------------
5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Sep
Daily Proton Fluence >1 MeV: 2.2E+06
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 1.80E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:14%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B8.9
DSCOVR Satellite Solar Wind Day Averaged Data for 17 Sep
Speed: 627 km/sec Density: 0.6 p/cc Temp: 110000 K Bz: 1 nT
(Courtesy Space Weather Prediction Center, Boulder USA)
-----------------------------------------------------------
Australian Space Weather Forecasting Centre
Bureau of Meteorology
ASWFC at bom.gov.au
www.bom.gov.au | www.sws.bom.gov.au
More information about the ips-dsgr
mailing list