[Ips-dsgr] ASWFC Daily Report - 16 December 25 issued 2330 UT on 16 Dec 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Wed Dec 17 10:30:50 AEDT 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/16 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 16 DECEMBER AND FORECAST FOR 17 DECEMBER - 19 DECEMBER
STATUS INDICATORS SOL:GREEN MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 16 Dec: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 16 Dec: 117/69
1B. SOLAR FORECAST
17 Dec 18 Dec 19 Dec
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 118/70 118/70 115/66
COMMENT: Solar activity on UT day 16-Dec was R0, with no solar
flares. There are currently five numbered sunspot regions on
the solar disk. Overall the regions are all either stable or
decaying, however several regions went through a short growth
phase before maturing. Solar activity is mostly expected to be
R0 over 17-19 Dec.
No CMEs were observed on UT day 16-Dec.
S0 solar radiation storm conditions were observed on UT day 16-Dec.
S0 solar radiation storm conditions are expected over 17-19 Dec.
On UT day 16-Dec the solar wind environment was mildly disturbed.
The solar wind speed steadily increased and ranged from 500-700km/s,
but is now coming down from its peak. The maximum total interplanetary
field strength (IMF, Bt) was 14nT and the north-south IMF component
range (Bz) was +12 to -8nT. The source of this disturbance was
likely a weak transience, or else possibly the early arrival of the
anticipated coronal hole. Should the coronal hole still be expected
to connect with Earth, the solar wind is expected to increase late on
17-Dec into 18-Dec. Otherwise, the solar wind is expected to return
to background levels.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 16 Dec: G0
Estimated Indices 16 Dec : A K
Australian Region 9 32222322
Cocos Island 6 22121312
Darwin 10 32222323
Townsville 10 33-22322
Learmonth 10 32222323
Alice Springs 8 32122322
Gingin 10 32222323
Canberra 7 32122222
Kennaook Cape Grim 9 32232222
Hobart 10 32233222
Estimated Antarctic Regional K Indices 16 Dec :
Macquarie Island 12 32243321
Casey 39 56653333
Mawson 25 44433435
Observed Regional daily pc3 Indices 16 Dec :
Darwin 0 (Quiet)
Townsville 39 (Quiet to unsettled)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 19 (Quiet)
Canberra 19 (Quiet)
Hobart 56 (Unsettled)
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 Dec : A
Fredericksburg 10
Planetary 11
Observed AFr/Ap Indices 15 Dec : A K
Fredericksburg 5
Planetary 6 1011 3211
2B. MAGNETIC FORECAST
Date Ap Conditions
17 Dec 14 G0, chance G1
18 Dec 20 G0-G1
19 Dec 12 G0
COMMENT: ASWFC Geomagnetic Warning 100 was issued on 15 December
and is current for 17-18 Dec. G0 geomagnetic conditions were
observed in the Australian region on UT day 16-Dec. G0-G2 geomagnetic
conditions were observed in the Antarctic region. Mostly G0 geomagnetic
conditions are expected on 17-Dec. A coronal hole is possibly
expected to connect with Earth either late 17-Dec or else early
18-Dec which may induce G1 conditions. G0 geomagnetic conditions
are expected on 19-Dec.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
16 Dec Normal-fair Normal-fair Fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
17 Dec Normal Normal Normal-fair
18 Dec Normal-fair Normal-fair Normal-fair
19 Dec Normal Normal Normal
COMMENT: HF radio propagation conditions on UT day 16-Dec were
normal to mildly degraded across the globe. HF radio propagation
conditions are expected to be mostly normal on 17-Dec, with possible
degradations beginning on 18-Dec. Conditions are expected to
be normal by 19-Dec.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
16 Dec 81
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values.
Niue Island Region:
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 15% over the UT day.
Monthly T index:
Month T index
Nov 103
Dec 89
Jan 89
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
17 Dec 95 Near predicted monthly values
18 Dec 90 Near predicted monthly values to 10-15% depressed
19 Dec 90 Near predicted monthly values to 10-15% depressed
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region were near predicted values on UT day 16-Dec. Sporadic-E
was observed in Brisbane and spread-F was observed in Hobart.
MUFs are expected to be near predicted values on 17-Dec. MUFs
may experience mild 10-15% depressions over 18-19 Dec.
Strong sporadic-E is expected to continue in Brisbane,
causing degraded signal propagation.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 15 Dec
Daily Proton Fluence >1 MeV: 8.3E+05
Daily Proton Fluence >10 MeV: 1.5E+04
Daily Electron Fluence >2 MeV: 2.70E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 4%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B5.0
DSCOVR Satellite Solar Wind Day Averaged Data for 15 Dec
Speed: 466 km/sec Density: 1.9 p/cc Temp: 92000 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
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