[Ips-dsgr] ASWFC Daily Report - 25 September 25 issued 2330 UT on 25 Sep 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Fri Sep 26 09:30:48 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/25 SEPTEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 25 SEPTEMBER AND FORECAST FOR 26 SEPTEMBER - 28 SEPTEMBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 25 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 25 Sep: 170/124
1B. SOLAR FORECAST
26 Sep 27 Sep 28 Sep
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 170/124 165/119 165/119
COMMENT: Solar activity on UT day 25-Sep was at the R0 level.
Solar region AR4230 (S11E43, beta) is growing, though currently
exhibiting a more open spot configuration. Solar region AR4226
(S11E03, beta) which was a region of interest is now in decay
with decline evident in its trailer spots. Smaller solar region
AR4227 (S17E03, alpha) just to the south of AR4226 is in decay.
Solar region AR4229 (S03W49, beta) initially showed development
in its trailer spots then they declined toward the end of the
UT day. The small surrounding spots of AR4217 (S14W79, beta)
are in decay as the region approaches the southwest solar limb.
There are currently ten numbered sunspot regions on the solar
disk. All other solar regions are either stable or in decay.
Solar activity is expected to be at the R0 level over 26-28 Sep.
There is some small emission on the northeast solar at solar
latitude N10, indicating a small solar region may soon rotate
onto the disk. No Earth-directed CMEs have been observed. S0
solar radiation storm conditions were observed on UT day 25-Sep.
S0 solar radiation storm conditions are expected over 26-28 Sep.
Two small sized coronal holes are currently located just west
of the solar central meridian and may increase the solar wind
late 27-Sept. The solar wind speed slowly declined on UT day
25-Sep ranged from 440 km/s to 515 km/s and is currently at 460
km/s. The peak total interplanetary field strength (IMF, Bt)
was 6 nT and the north-south IMF component (Bz) range was +5
to -4 nT. The solar wind is expected to continue to slowly decline
with a slight increase late on 27-Sept due to the small coronal
holes.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 25 Sep: G0
Estimated Indices 25 Sep : A K
Australian Region 6 11223112
Cocos Island 5 22212111
Darwin 8 22213213
Townsville 6 11123122
Learmonth 7 22223221
Alice Springs 6 11223112
Gingin 7 22213222
Canberra 4 11212112
Kennaook Cape Grim 6 11223112
Hobart 6 11223112
Estimated Antarctic Regional K Indices 25 Sep :
Macquarie Island 7 11134111
Casey 20 35523232
Mawson 18 23332354
Observed Regional daily pc3 Indices 25 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 29 (Quiet to unsettled)
Canberra 26 (Quiet to unsettled)
Hobart 18 (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 25 Sep : A
Fredericksburg 8
Planetary 8
Observed AFr/Ap Indices 24 Sep : A K
Fredericksburg 6
Planetary 8 2212 2223
2B. MAGNETIC FORECAST
Date Ap Conditions
26 Sep 5 G0
27 Sep 12 G0, slight chance G1
28 Sep 12 G0, slight chance G1
COMMENT: G0 geomagnetic conditions were observed in the Australian
region on UT day 25-Sep. In the Antarctic region G0-G1 geomagnetic
conditions were observed. G0 conditions are expected on 26-Sep.
G0 with a slight chance of G1 are expected during 27-28 Sep due
to the influence of weak coronal hole wind streams.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
25 Sep Normal Fair-normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
26 Sep Normal Normal Normal
27 Sep Normal Normal-fair Fair
28 Sep Normal Normal-fair Fair
COMMENT: HF radio propagation conditions on UT day 25-Sep were
fair to normal. HF radio propagation conditions are expected
to be mostly normal over 26-28 Sep, with fair conditions possible
for middle to high latitudes during 27-28 Sep during local night
hours. Isolated minor shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
25 Sep 129
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 55% during local day.
Enhanced by 85% during local night.
Niue Island Region:
Enhanced by 15-20% during local day.
Northern Australian Region:
Enhanced by 15%.
Southern Australian Region:
Near predicted monthly values during local day.
Enhanced by 20% during local night.
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
26 Sep 110 Near to 15% above predicted monthly values
27 Sep 110 Near to 15% above predicted monthly values
28 Sep 110 Near to 15% above predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 25-Sep were near predicted values to 20% enhanced.
Spread F was observed at Hobart, Canberra and Perth during local
night hours. Very strong enhancements of up to 85% were observed
at Cocos Island during the interval 25/0600-1900UT. MUFs are
expected to be near predicted values to 15% enhanced over 26-28
Sep. Mildly degraded HF conditions may be experienced for the
southern Australian region during local night hours on 27-28
Sep. Isolated minor shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 24 Sep
Daily Proton Fluence >1 MeV: 7.1E+05
Daily Proton Fluence >10 MeV: 1.6E+04
Daily Electron Fluence >2 MeV: 2.20E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 4%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.7
DSCOVR Satellite Solar Wind Day Averaged Data for 24 Sep
Speed: 520 km/sec Density: 0.1 p/cc Temp: 81600 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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