[Ips-dsgr] ASWFC Daily Report - 26 December 25 issued 2330 UT on 26 Dec 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sat Dec 27 10:30:50 AEDT 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/26 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 26 DECEMBER AND FORECAST FOR 27 DECEMBER - 29 DECEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 26 Dec: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 26 Dec: 166/120
1B. SOLAR FORECAST
27 Dec 28 Dec 29 Dec
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 170/124 175/129 170/124
COMMENT: Solar activity on UT day 26-Dec was R0. Solar region
AR4317 (N11W03,beta) showed some umbral redistribution in its
leader spot and decay in its trailer spots. Solar region AR4321
(S11W35, beta) is decaying with a decrease in umbral area and
an increase in penumbral area and exhibits a north-south magnetic
polarity orientation rather than the more typical east-west orientation.
These two medium sized regions are the larger of the on disk
regions. A new medium sized region is rotating onto the solar
disk over the northeast limb at solar latitude N26. Region AR4323
(S10E80, alpha) is a small solar region in the southeast quadrant.
Just to the southwest of this region are possibly the returned
remnants of decayed AR4294 in an area of faculae and possibly
very small spots/pores. There is still some east limb emission
at S15 which may possibly be the return of AR4296, though the
plasma arch activity doesn't appear to be that significant. Solar
regions AR4317 and AR4323 produced isolated C class flare activity,
with the largest a C6.9 at 26/0914UT from AR4323. There are currently
eight numbered sunspot regions and one unnumbered region on the
solar disk. All other sunspot regions are small and either stable
or in decay. Solar activity is expected to be R0-R1 over 27-29
Dec. No Earth directed CMEs were observed on UT day 26-Dec. A
faint south southeast directed CME was observed from 26/1436UT
which could not be correlated to on disk activity. S0 solar radiation
storm conditions were observed on UT day 26-Dec. S0 solar radiation
storm conditions are expected over 27-29 Dec. The solar wind
speed on UT day 26-Dec was moderate to strong and slightly declined
as the influence of a coronal hole slowly abates. The solar wind
speed ranged from 508 to 570 km/s and is currently at 520 km/s.
The peak total interplanetary field strength (IMF, Bt) was 6
nT and the north-south IMF component range was +4 to -4 nT. The
solar wind is expected to continue to slowly decline. Whilst
the transequatorial section of the coronal hole that is currently
influencing the solar wind is now well west on the solar disk,
another shorter south polar extension section of this hole is
now just past the solar central meridian. This may cause the
solar wind to decline more slowly over coming days. An isolated
coronal hole is visible in the northeast solar quadrant with
centre location at N20E30.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 26 Dec: G0
Estimated Indices 26 Dec : A K
Australian Region 5 12222211
Cocos Island 5 12222210
Darwin 7 22222312
Townsville 5 12212221
Learmonth 7 22222312
Alice Springs 5 12222211
Gingin 7 22222312
Canberra 5 02222212
Kennaook Cape Grim 5 12222211
Hobart 6 12222212
Estimated Antarctic Regional K Indices 26 Dec :
Macquarie Island 8 13223311
Casey 28 46543322
Mawson 15 34333313
Observed Regional daily pc3 Indices 26 Dec :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 13 (Quiet)
Canberra 4 (Quiet)
Hobart 14 (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 26 Dec : A
Fredericksburg 7
Planetary 8
Observed AFr/Ap Indices 25 Dec : A K
Fredericksburg 8
Planetary 11 3332 2212
2B. MAGNETIC FORECAST
Date Ap Conditions
27 Dec 8 G0
28 Dec 8 G0
29 Dec 10 G0
COMMENT: G0 geomagnetic conditions were observed in the Australian
region on UT day 26-Dec. G0-G2 geomagnetic conditions were observed
in the Antarctic region. G0 geomagnetic conditions are expected
over 27-29 Dec.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
26 Dec Normal Normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
27 Dec Normal Normal Fair-normal
28 Dec Normal Normal Fair-normal
29 Dec Normal Normal Fair-normal
COMMENT: HF radio propagation conditions on UT day 26-Dec were
mostly normal. HF radio propagation conditions are expected to
be mostly normal over 27-29 Dec. Isolated minor shortwave fadeouts
are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
26 Dec 128
Observed Australian Regional MUFs
Cocos Island Region:
No data available.
Niue Island Region:
Near predicted monthly values.
Northern Australian Region:
Near predicted monthly values during local day.
Enhanced by 25% during local night.
Southern Australian Region:
Near predicted monthly values during local day.
Enhanced by 15% during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values 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
27 Dec 115 Near predicted monthly values to 15% enhanced
28 Dec 115 Near predicted monthly values to 15% enhanced
29 Dec 115 Near predicted monthly values to 15% enhanced
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 26-Dec were near predicted values to 25% enhanced.
Mild depressions were observed after local dawn at some sites
which are not expected to persist. MUFs are expected to be near
predicted values to 15% enhanced over 27-29 Dec. Isolated minor
shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 25 Dec
Daily Proton Fluence >1 MeV: 2.3E+06
Daily Proton Fluence >10 MeV: 1.7E+04
Daily Electron Fluence >2 MeV: 2.90E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:18%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.4
DSCOVR Satellite Solar Wind Day Averaged Data for 25 Dec
Speed: 587 km/sec Density: 2.2 p/cc Temp: 135000 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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