[Ips-dsgr] ASWFC Daily Report - 30 September 25 issued 2330 UT on 30 Sep 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Wed Oct 1 09:30:49 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/30 SEPTEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 30 SEPTEMBER AND FORECAST FOR 01 OCTOBER - 03 OCTOBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 30 Sep: R1
Flares Max Fadeout Freq. Sectors
M1.2 0056UT possible lower West Pacific
M2.7 0940UT possible lower Mid East/Indian
M1.8 1227UT possible lower European
Observed 10.7 cm flux/Equivalent Sunspot Number for 30 Sep: 187/140
1B. SOLAR FORECAST
01 Oct 02 Oct 03 Oct
Activity R1,chance R2 R1,chance R2 R1,chance R2
Fadeouts Possible Possible Possible
10.7cm/SSN 185/138 180/133 180/133
COMMENT: Solar activity on UT day 30-Sep was at the R1 level.
Solar region AR4232 (N05E27, gamma) produced an M1.2 flare at
30/0056UT, region AR4226 (S10W56, alpha) produced an M2.7 flare
at 30/0940UT and region AR4238 (S16W37, beta) produced an M1.8
flare at 30/1227UT. Solar region AR4236 (N12E19, beta-gamma)
despite being relatively large and magnetically complex produced
only infrequent lower C class flare activity. Solar region AR4236
has grown rapidly and AR4232 is also showing growth. Solar region
AR4226 a more magnetically simple monopole showed umbral decay
later in the UT day. Solar regions AR4230 (S10W33, beta), AR4239
(S10W41, alpha) and AR4238 are in close proximity in the southwest
quadrant of the solar disk. Solar region AR4230 is growing, with
the regions leader spot expanding and squeezing against the single
spot of region AR4239 and the penumbra of these two spots now
appears to have cojoined. These two merging penumbra however
have the same magnetic polarity. AR4238 just south of these two
regions is also showing growth. An erupting solar prominence
was observed on the southwest limb spanning S10-S30 from 30/0836UT.
There are currently ten numbered sunspot regions on the solar
disk. All other sunspot regions are stable or in decaying. Solar
activity is expected to be R1 with isolated R2 flares possible
over 01-Oct to 03-Oct. No significantly Earth directed CMEs were
observed. A faint narrow and slow east directed CME was observed
from 30/0224UT in LASCO C2 imagery is not considered significant,
possibly associated with the M1.2 flare. A fast southwest directed
CME was observed from 30/0948UT in LASCO C2 imagery associated
with the erupting solar prominence on the southwest solar limb.
This CME has been modelled as an Earth miss and is expected to
pass ahead of the Earth. S0 solar radiation storm conditions
were observed on UT day 30-Sep. S0 solar radiation storm conditions
are expected over 01-Oct to 03-Oct. Two moderately large isolated
coronal holes currently have started crossing the solar central
meridian. On UT day 30-Sep the solar wind speed gradually increased
from approximately 30/1100UT. The solar wind speed ranged from
416 to 700 km/s and is currently at 700 km/s. The interplanetary
magnetic field Bt became moderately enhanced. The peak interplanetary
magnetic field strength (IMF, Bt) was 20 nT and the north-south
IMF component range (Bz) was +16 to -16 nT. A prolonged interval
of moderately southward IMF conditions was observed 30/0200-0600UT
and slightly southward IMF conditions were observed 30/1200-1700UT.
The solar phi angle (the magnetic field direction in the ecliptic
plane) swung from toward to away from 30/0500UT. The solar wind
density decreased over the UT day. These solar wind parameter
changes suggest the disturbed conditions may indicate a corotating
interactive region (CIR) in the the solar wind that preceded
a possible coronal hole wind stream entry. The 27 day recurrent
geomagnetic patterns however are only somewhat aligned with this
presumption. THE ACE EPAM CME low energy ion precursor data channel
remained flat over the last three days suggesting no CME arrival.
The solar wind is now expected to remain strong for today. A
27 day recurrent pattern is present for 02-03 Oct however this
is now ambiguous considering what appears to be a wind stream
entry that matches the polarity of the holes now crossing the
solar central meridian.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 30 Sep: G1
Estimated Indices 30 Sep : A K
Australian Region 33 34455445
Cocos Island 22 34334444
Darwin 33 34455445
Townsville 31 34355445
Learmonth 36 34455554
Alice Springs 29 34355444
Gingin 31 43355544
Canberra 32 24455445
Kennaook Cape Grim 38 35455545
Hobart 40 36455445
Estimated Antarctic Regional K Indices 30 Sep :
Macquarie Island 68 47566655
Casey 27 55344334
Mawson 92 58555477
Observed Regional daily pc3 Indices 30 Sep :
Darwin 11 (Quiet)
Townsville 6 (Quiet)
Learmonth 4 (Quiet)
Alice Springs 4 (Quiet)
Gingin 34 (Quiet to unsettled)
Canberra 63 (Active)
Hobart 124 (Severe 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 30 Sep : A
Fredericksburg 40
Planetary 64
Observed AFr/Ap Indices 29 Sep : A K
Fredericksburg 13
Planetary 27 3345 4553
2B. MAGNETIC FORECAST
Date Ap Conditions
01 Oct 20 G1 then declining to G0 late in UT day
02 Oct 10 G0, chance G1 late in UT day
03 Oct 20 G1
COMMENT: G1 geomagnetic conditions were observed in the Australian
region on UT day 30-Sep associated with southward orientated
interplanetary magnetic field conditions. Planetary conditions
reached G3 on 30-Sep. The cause of the recent enhanced southward
IMF conditions is not definitive but appears to have preceded
a coronal hole wind stream entry. In the Antarctic region G4
conditions were observed at Mawson, G3 geomagnetic conditions
were observed at Macquarie Island, G1 conditions were observed
at Casey. G1 geomagnetic periods are expected on 01-Oct, then
declining to G0 by 02-Oct with 27 day recurrent patterns suggesting
possible G1 periods from late in the UT day on 02-Oct and on
03-Oct.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
30 Sep Normal Poor-fair Poor
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
01 Oct Normal Fair Poor-fair
02 Oct Normal Normal Normal-fair
03 Oct Normal Normal-fair Fair
COMMENT: HF radio propagation conditions on UT day 30-Sep were
poor to normal, with degraded HF conditions at middle to high
latitudes due to G3 geomagnetic activity. Increased absorption
of up to 3db was observed on the 30MHz riometer at Davis and
Mawson 30/0300-0400UT and at Macquarie Island 30/1700-2000UT.
HF radio propagation conditions are expected to be fair to poor
to middle at high latitudes for 01-Oct with middle to low latitudes
remaining normal. HF conditions at middle to high latitudes may
become mildly degraded late in the UT day on 02-Oct and into
03-Oct.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
30 Sep 88
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 30% during local day.
Near predicted monthly values during local night.
Enhanced by 45% after local dawn.
Niue Island Region:
Enhanced by 20% during local day.
Enhanced by 30% during local night.
Northern Australian Region:
Enhanced by 15% during local day.
Near predicted monthly values during local night.
Southern Australian Region:
Depressed by 30% during local day.
Depressed by 25% during local night.
Depressed by 20% after local dawn.
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
01 Oct 75 Depressed 15 to 20%/near predicted monthly values
02 Oct 110 Near predicted monthly values
03 Oct 110 Near predicted monthly values
COMMENT: ASWFC SWF HF Communications Warning 86 was issued on
28 September and is current for 29 Sep to 1 Oct. Maximum usable
frequencies (MUFs) in the Australian region on UT day 30-Sep
were variable. Northern Australian region MUFs were generally
15% enhanced. MUFs in the southern Australian region were depressed
20-30%. Southern Australian MUFs were depressed 20% after local
dawn this morning. Spread F was observed at Hobart and Canberra
during local night hours. Southern Australian region MUFs are
expected to be depressed 15-20% on 01-Oct. Northern region MUFs
are expected to be near predicted monthly values to 15% enhanced
for 01-Oct. Isolated minor shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 29 Sep
Daily Proton Fluence >1 MeV: 6.0E+05
Daily Proton Fluence >10 MeV: 1.5E+04
Daily Electron Fluence >2 MeV: 1.10E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 2%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.7
DSCOVR Satellite Solar Wind Day Averaged Data for 29 Sep
Speed: 391 km/sec Density: 1.6 p/cc Temp: 33100 K Bz: -7 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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