[Ips-dsgr] ASWFC Daily Report - 13 December 25 issued 2330 UT on 13 Dec 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sun Dec 14 10:30:48 AEDT 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/13 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 13 DECEMBER AND FORECAST FOR 14 DECEMBER - 16 DECEMBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 13 Dec: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 13 Dec: 122/75
1B. SOLAR FORECAST
14 Dec 15 Dec 16 Dec
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 120/72 120/72 120/72
COMMENT: Solar activity was at the R0 level for UT day 13-Dec.
No significant flares were observed with solar region AR4296
(S15W83, beta) producing the largest flare of the day a C8.6
at 13/1051UT. Region AR4296 is rotating off disk. There is currently
no solar region of significant area on the visible solar disk.
Solar regions AR4307 (S13W17, beta-gamma) and AR4308 (N11E46,
beta) have shown minor growth. There are currently five regions
on the visible solar disk. Other regions are stable or in decay.
Plasma ejecta was observed on the southwest solar limb at solar
latitude S20 from 13/1057UT in GOES 304 imagery. R0 conditions
are forecast for 14-16 Dec. S0 solar radiation storm conditions
were observed on 13-Dec. S0 solar radiation storm conditions
are expected over 14-16 Dec. The western arm of a north polar
extension coronal hole is now past the solar central meridian,
with the longer eastern arm of the hole just to the east of the
central meridian. No geoeffective coronal mass ejections were
observed over the past UT day. A southwest directed CME was observed
in LASCO C2 imagery from 13/1112UT in association with the plasma
ejecta on the southwest solar limb and is expected to pass well
ahead of the Earth. The solar wind speed increased to strong
due to the influence from the arm of the coronal hole now west
of the centre of the solar disk. The solar wind speed ranged
between 472-689 km/s and is currently at 689 km/s. The peak total
interplanetary magnetic field strength (IMF, Bt) was 17 nT and
the north-south IMF component (Bz) range was -6 to 15 nT. The
interplanetary magnetic field strength was enhanced up to 13/0900UT
then dropped as the Earth entered the coronal wind stream and
is now a very small magnitude of approximately 4 nT. The IMF
Bz was mildly southward (-6 nT) early in the UT day then became
orientated northwards. Coronal hole high speed wind stream effects
are expected to sustain elevated wind speed conditions on 14-Dec,
with the IMF expected to remain small in magnitude.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 13 Dec: G0
Estimated Indices 13 Dec : A K
Australian Region 10 32223322
Cocos Island 7 32222221
Darwin 12 42223323
Townsville 11 32233322
Learmonth 12 32233332
Alice Springs 10 32223322
Gingin 12 42223332
Canberra 11 32233322
Kennaook Cape Grim 14 42324322
Hobart 12 42323322
Estimated Antarctic Regional K Indices 13 Dec :
Macquarie Island 16 32335232
Casey 47 55764332
Mawson 30 53443363
Observed Regional daily pc3 Indices 13 Dec :
Darwin 4 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 13 (Quiet)
Canberra 17 (Quiet)
Hobart 44 (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 13 Dec : A
Fredericksburg 11
Planetary 14
Observed AFr/Ap Indices 12 Dec : A K
Fredericksburg 19
Planetary 28 4434 3355
2B. MAGNETIC FORECAST
Date Ap Conditions
14 Dec 10 G0
15 Dec 8 G0
16 Dec 6 G0
COMMENT: ASWFC Geomagnetic Warning 99 was issued on 13 December
and is current for 13-14 Dec. G0 geomagnetic conditions were
observed in the Australian region on UT day 13-Dec. Geomagnetic
activity was mildly elevated early in the UT day in association
with southward IMF conditions. Periods of G1-G3 geomagnetic conditions
were observed in the Antarctic region. Planetary conditions were
at G1 early in the UT day. The Earth entered a coronal hole wind
stream later in the UT day with little influence on the geomagnetic
field due to the IMF dropping to a very small magnitude after
wind stream entry. G0 conditions are now generally expected over
14-16 Dec.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
13 Dec Normal Fair Fair-poor
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
14 Dec Normal Fair-normal Fair
15 Dec Normal Normal Normal-fair
16 Dec Normal Normal Normal
COMMENT: HF radio propagation conditions on UT day 13-Dec were
fair to poor, with poor conditions at times at high latitudes.
HF conditions at middle to high latitudes are expected to be
fair on 14-Dec and fair to normal on 15-16 Dec with an improving
trend.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
13 Dec 28
Observed Australian Regional MUFs
Cocos Island Region:
Depressed by 50% during local day.
Depressed by 35% during local night.
Depressed by 20% after local dawn.
Niue Island Region:
Near predicted monthly values during local day.
Enhanced by 30% during local night.
Enhanced by 20% after local dawn.
Northern Australian Region:
Depressed by 35% during local day.
Near predicted monthly values during local night.
Southern Australian Region:
Depressed by 30% during local day.
Near predicted monthly values during local night.
Depressed by 25% after local dawn.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 25% 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
14 Dec 70 Depressed 15 to 20%/near predicted monthly values
15 Dec 85 Near predicted monthly values
16 Dec 85 Near predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 13-Dec were 35% depressed to near predicted
monthly values, with depressed conditions observed during the
local day. Sporadic E was observed during local night hours.
MUFs in the southern Australian region are 20% depressed after
local dawn this morning. MUFs are expected to be initially 15-20%
depressed on 14-Dec then gradually recovering and near predicted
monthly values. MUFs are expected to be near predicted monthly
values on 15-16 Dec.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 12 Dec
Daily Proton Fluence >1 MeV: 8.8E+05
Daily Proton Fluence >10 MeV: 1.4E+04
Daily Electron Fluence >2 MeV: 2.00E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.0
DSCOVR Satellite Solar Wind Day Averaged Data for 12 Dec
Speed: 436 km/sec Density: 5.4 p/cc Temp: 81300 K Bz: -6 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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