[Ips-dsgr] ASWFC Daily Report - 04 October 25 issued 2330 UT on 04 Oct 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sun Oct 5 10:30:50 AEDT 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/04 OCTOBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 04 OCTOBER AND FORECAST FOR 05 OCTOBER - 07 OCTOBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 04 Oct: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 04 Oct: 158/112
1B. SOLAR FORECAST
05 Oct 06 Oct 07 Oct
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 160/114 160/114 165/119
COMMENT: Solar activity on UT day 04-Oct was R0. Solar regions
AR4232 (N05W27, beta), AR4241 (N16E09, beta) and AR4242 (S11E17,
beta-gamma) produced low level C class flares. The two larger on disk
solar regions AR4236 (N12W34, beta-gamma) and AR4232 are slowly decaying.
Smaller regions AR4242 and AR4241 are slowly growing. There are
currently eight numbered solar regions on the visible solar disk.
All other sunspot regions are either stable or in decay. Solar
flare activity is expected to be R0-R1 over 05-07 Oct. No significant
Earth directed CMEs have been observed. A review of STEREO-A
imagery showed that yesterday's M1.5 flare from AR4236 was associated
with a minor CME that was not visible in LASCO imagery. This
CME was modelled using STEREO-A imagery and a weak Earth arrival
is expected at 06/0500UT +/- 12 hours. On 04-Oct a sequence of
west directed CMEs were visible in LASCO C2 imagery during the
interval 04/0500-2000UT, mostly northwest directed. These CMEs
could not be correlated to any on disk plasma motion in GOES
SUVI 195 imagery. Yesterday, numerous overlapping eastward non-Earth
directed CMEs were observed, with several associated with filament
eruptions. In particular, a faint slow CME front expanding initially
to the southeast and then to the southwest was visible from 03/2100UT
and may be related to the southeast filament eruption at 03/1925UT.
However the modelled speed was extremely slow at 270km/sec and
is considered an insignificant arrival at 08/0300UT +/- 12 hours.
S0 solar radiation storm conditions were observed on UT day 04-Oct.
S0 solar radiation storm conditions are expected over 05-07 Oct.
The influence of a broad coronal hole now located in the south
western solar quadrant is reducing as it moves further away from
the solar central meridian. The solar wind speed is declining
and ranged from 670 to 560 km/s, and is currently near 560 km/s.
The total interplanetary field strength (IMF, Bt) peaked at 8
nT. The north-south IMF component range (Bz) was +3 to -5 nT.
The magnitude of the IMF Bt is currently small. The solar wind
speed is expected to further decline on 05-Oct, with a minor
disturbance to the solar wind during 06-07 Oct due to a possible
weak CME arrival. The GOES 2MeV electron flux is currently strongly
elevated, which is statistically associated with an increased
rate of geosynchronous orbiting satellite anomalies. An equatorial
coronal hole is visible in the eastern solar hemisphere at solar
longitude E50.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 04 Oct: G0
Estimated Indices 04 Oct : A K
Australian Region 14 23344321
Cocos Island 8 22233220
Darwin 12 23333322
Townsville 14 23344321
Learmonth 12 22343321
Alice Springs 13 23343321
Gingin 14 22344331
Canberra 13 23344221
Kennaook Cape Grim 18 23454321
Hobart 18 23454321
Estimated Antarctic Regional K Indices 04 Oct :
Macquarie Island 50 25676431
Casey 17 44432332
Mawson 49 54644664
Observed Regional daily pc3 Indices 04 Oct :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 28 (Quiet to unsettled)
Canberra 38 (Quiet to unsettled)
Hobart 41 (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 04 Oct : A
Fredericksburg 15
Planetary 20
Observed AFr/Ap Indices 03 Oct : A K
Fredericksburg 20
Planetary 30 4554 334-
2B. MAGNETIC FORECAST
Date Ap Conditions
05 Oct 12 G0
06 Oct 16 G0-G1
07 Oct 15 G0-G1
COMMENT: ASWFC Geomagnetic Warning 77 was issued on 4 October
and is current for 6-7 Oct. G0 geomagnetic conditions were observed
in the Australian region on UT day 04-Oct. The Australian regional
geomagnetic field was mildly active due to the ongoing influence
of a coronal hole high speed wind stream. In the Antarctic region
G2-G3 geomagnetic conditions were observed at Mawson and Macquarie
Island, with G0 conditions observed at Casey. G0 geomagnetic
activity is expected on 05-Oct. G1 periods may be experienced
over 06-07 Oct due to a possible weak CME arrival.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
04 Oct Normal Fair-normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
05 Oct Normal Fair-normal Fair-normal
06 Oct Normal Normal-fair Fair
07 Oct Normal Normal-fair Fair
COMMENT: HF radio propagation conditions were fair to normal
on 04-Oct. Increased absorption of 1-3db was observed at times
on the Macquarie Island 30Mhz riometer during the interval 04/0900-2100UT.
HF conditions are expected to be fair to normal on 05-Oct, with
fair conditions at middle to high latitudes. Middle to high latitude
conditions may become mildly degraded 06-07 Oct during local
night hours due to a possible weak CME arrival.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
04 Oct 121
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 20-30%.
Niue Island Region:
Enhanced by 25% during local day.
Near predicted monthly values during local night.
Enhanced by 25% after local dawn.
Northern Australian Region:
Enhanced by 25% during local day.
Enhanced by 40% during local night.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Sep 109
Oct 89
Nov 89
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
05 Oct 80 Depressed 15 to 20%/near predicted monthly values
06 Oct 110 Near predicted monthly values to 15% enhanced
07 Oct 110 Near predicted monthly values to 15% enhanced
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 04-Oct were near predicted values to 40% enhanced.
Spread F was observed at Hobart and Canberra during local night
hours. Australian region MUFs have become depressed by 15-30%
after 04/2200UT. The cause of this ionospheric frequency depression
is unclear. MUFs are expected to be 15-20% depressed to near
predicted monthly values for the Australian region for 05-Oct.
MUFs are expected to be near predicted monthly values to 15%
enhanced over 06-07 Oct, with mildly degraded conditions during
local night hours for the southern Australian region.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 03 Oct
Daily Proton Fluence >1 MeV: 3.3E+06
Daily Proton Fluence >10 MeV: 2.1E+04
Daily Electron Fluence >2 MeV: 2.80E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:18%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.7
DSCOVR Satellite Solar Wind Day Averaged Data for 03 Oct
Speed: 705 km/sec Density: 0.8 p/cc Temp: 211000 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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