[Ips-dsgr] ASWFC Daily Report - 16 September 25 issued 2330 UT on 16 Sep 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Wed Sep 17 09:30:49 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/16 SEPTEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 16 SEPTEMBER AND FORECAST FOR 17 SEPTEMBER - 19 SEPTEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 16 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 16 Sep: 135/89
1B. SOLAR FORECAST
17 Sep 18 Sep 19 Sep
Activity R0, chance of R1 R0, chance of R1 R0, chance of R1
Fadeouts Possible Possible Possible
10.7cm/SSN 138/92 138/92 140/94
COMMENT: Solar activity on UT day 16-Sep was at R0. There are
currently nine numbered regions visible on the solar disk. AR4216
(N11E17,beta) is the largest region on the disk and has shown
a mixture of growth and slight decay in its intermediate spots.
AR4217 (S15E48,beta) has showed a reorganisation of its leaders
spots. AR4221 (N04E45,beta) has shown some growth in the leader
spot. AR4220 (S18E15,beta) and AR4224(S10E50,beta) are both small
regions which have shown some growth over the UT day. AR4225
(N14E80,beta) is a new larger spot which has rotated onto the
solar disk which appears beta complexity however is difficult
to classify noting its proximity to the limb. All other sunspot
regions are either stable or in decay. Solar activity is expected
to be at the R0, chance of R1 over 17-19 Sep. No Earth directed
CMEs have been observed however several eastward non earth directed
CME were observed. Early in the UT day a southeast directed CME
was observed in association with an erupting east limb solar
prominence. Plasma ejecta was observed in SUVI 094 imagery at
16/1240UT possibly attributed to C class flare activity from
AR4223 and a corresponding CME observed in LASCO C2 imagery from
16/1524UT. The small CME was slow moving and unlikely to impact
earth. Two small disappearing solar filaments were observed,
S30E20 at 16/1338UT and N22W22 at 16/1501UT with no associated
CMEs observed. S0 solar radiation storm conditions were observed
on UT day 16-Sep. S0 solar radiation storm conditions are expected
over 17-19 Sep. The solar wind speed on UT day 16-Sep remained
elevated throughout the day ranging from 670 to 800 km/s and
is currently near 670 km/s. The solar wind speed is very strong
and is expected to start to decline over 17 Sep due to the coronal
hole moving out of a geoeffective position. The peak total interplanetary
magnetic field strength (IMF, Bt) was 6 nT and the north-south
IMF component (Bz) range was -5 to +6nT.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 16 Sep: G0
Estimated Indices 16 Sep : A K
Australian Region 12 33333222
Cocos Island 6 22322111
Darwin 13 33333223
Townsville 13 33343222
Learmonth 13 33333322
Alice Springs 12 33333222
Gingin 13 33333322
Canberra 13 33433222
Kennaook Cape Grim 15 33443222
Hobart 15 33443222
Estimated Antarctic Regional K Indices 16 Sep :
Macquarie Island 26 33555332
Casey 19 45433222
Mawson 47 55553366
Observed Regional daily pc3 Indices 16 Sep :
Darwin 14 (Quiet)
Townsville 4 (Quiet)
Learmonth 23 (Quiet to unsettled)
Alice Springs 13 (Quiet)
Gingin 103 (Major storm)
Canberra 107 (Major storm)
Hobart 103 (Major storm)
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 16 Sep : A
Fredericksburg 17
Planetary 22
Observed AFr/Ap Indices 15 Sep : A K
Fredericksburg 34
Planetary 48 7555 5544
2B. MAGNETIC FORECAST
Date Ap Conditions
17 Sep 14 G0, chance of G1
18 Sep 10 G0
19 Sep 10 G0
COMMENT: G0 geomagnetic conditions were observed in the Australian
and G1 with isolated G2 conditions in Antarctic regions on UT
day 16-Sep. Planetary conditions briefly reached G1 early in
the UT day in association with a brief southward IMF conditions
during very strong winds due to a coronal hole. The wind stream
from this coronal hole is a chance of causing isolated periods
of G1 geomagnetic conditions on 17-Sep. G0 conditions are expected
on 18-19 Sep.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
16 Sep Normal Normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
17 Sep Normal Normal Normal-fair
18 Sep Normal Normal Normal-fair
19 Sep Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 16-Sep were
degraded at high latitudes. HF radio propagation conditions are
expected to be normal, grading fair to normal over high latitudes
over 17-19 Sep due to declining geomagnetic activity induced
by coronal hole wind stream. Increased absorption of up to 2db
was observed at times between 16/0000-0200UT and 16/1200-1500UT
at Macquarie Island.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
16 Sep 96
Observed Australian Regional MUFs
Cocos Island Region:
No data available.
Niue Island Region:
Mostly near predicted monthly values.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 30% 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
17 Sep 100 Near predicted monthly values
18 Sep 100 Near predicted monthly values
19 Sep 100 Near predicted monthly values
COMMENT: ASWFC HF Communications Warning 84 was issued on 15
September and is current for 15-17 Sep. Maximum usable frequencies
(MUFs) on UT day 16-Sep were mostly near predicted values. Spread-F
was observed in Perth and Hobart during local night hours. MUFs
are expected to be near predicted values on 17-19 Sep.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 15 Sep
Daily Proton Fluence >1 MeV: N/A
Daily Proton Fluence >10 MeV: N/A
Daily Electron Fluence >2 MeV: N/A
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: N/A
DSCOVR Satellite Solar Wind Day Averaged Data for 15 Sep
Speed: 668 km/sec Density: 2.6 p/cc Temp: 375000 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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