[Ips-dsgr] ASWFC Daily Report - 31 May 25 issued 2330 UT on 31 May 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sun Jun 1 09:30:48 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/31 MAY 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 31 MAY AND FORECAST FOR 01 JUNE - 03 JUNE
STATUS INDICATORS SOL:** RED ** MAG:** RED ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 31 May: R2
Flares Max Fadeout Freq. Sectors
M8.2 0005UT probable lower West Pacific
M2.4 0518UT possible lower E. Asia/Aust.
M4.5 0818UT possible lower Mid East/Indian
M2.9 1549UT possible lower South American/
Atlantic
Observed 10.7 cm flux/Equivalent Sunspot Number for 31 May: 164/118
1B. SOLAR FORECAST
01 Jun 02 Jun 03 Jun
Activity R1-R2 R1-R2 R1-R2
Fadeouts Probable Probable Probable
10.7cm/SSN 165/119 160/114 150/105
COMMENT: Solar activity on UT day 31-May was at the R2 level
due to a long duration M8.2 flare at 31/0005UT. There were also
three, impulsive, R1 level M-class flares over the UT day. There
are currently five numbered sunspot regions visible on the solar
disk. AR4100 (N07E01, gamma-delta) is the largest and most magnetically
complex sunspot region on the solar disk. This region underwent
some trailer spot simplification over the UT day but still has
two delta spot candidates and was responsible for all the M-class
flares of the UT day. AR4104 (N05E31, beta) also showed spot
development, but remains magnetically simple. All other sunspot
regions are stable or in decay. Solar activity is expected to
be at R1-R2 levels over 01-03 Jun. S1 solar radiation storm conditions
were observed on 31-May. S1 conditions, with a chance of S2 are
expected on 01-Jun. S0-S1 conditions are expected on 02-Jun.
S0 conditions, with a chance of S1 are expected on 03-Jun. A
fast, halo CME was observed from 31/0012UT in SOHO and STEREO-A
imagery associated with the M8.2 flare at 31/0005UT. This CME
is expected to impact Earth at 2100UT on 01-Jun +/- 12 hours.
The solar wind speed on UT day 31-May was steady and elevated,
mostly ranging between 580 to 820 km/s and is currently near
680 km/s. The peak total interplanetary magnetic field strength
(IMF, Bt) was 7 nT and the north-south IMF component (Bz) range
was -6 to +6 nT. Elevated solar wind speeds are expected over
the period 01-03 Jun. An increase in solar wind speed is expected
on 01-Jun at around 2100UT due to the anticipated arrival of
a halo CME first observed on 31-May.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 31 May: G0
Estimated Indices 31 May : A K
Australian Region 9 22223223
Cocos Island 7 22212223
Darwin 9 22223223
Townsville 10 22323223
Learmonth 10 22223233
Alice Springs 9 22223223
Gingin 12 32223234
Canberra 10 22323223
Kennaook Cape Grim 11 22324223
Hobart 12 22334223
Estimated Antarctic Regional K Indices 31 May :
Macquarie Island 27 33356333
Casey 17 34333234
Mawson 44 55444347
Observed Regional daily pc3 Indices 31 May :
Darwin 8 (Quiet)
Townsville 8 (Quiet)
Learmonth 4 (Quiet)
Alice Springs 6 (Quiet)
Gingin 51 (Unsettled)
Canberra 60 (Unsettled)
Hobart 85 (Minor 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 31 May : A
Fredericksburg 14
Planetary 18
Observed AFr/Ap Indices 30 May : A K
Fredericksburg 18
Planetary 16 ---- ----
2B. MAGNETIC FORECAST
Date Ap Conditions
01 Jun 75 G3-G4
02 Jun 100 G4
03 Jun 45 G1-G2
COMMENT: ASWFC Geomagnetic Warning 41 was issued on 31 May and
is current for 1-3 Jun. G0 geomagnetic conditions were observed
in the Australian region during the UT day 31-May. Mostly G1
conditions were observed in the Antarctic region, with an isolated
period of G2 at Macquarie Island and G3 at Mawson. G3-G4 geomagnetic
conditions are expected on 01-Jun (in the second half of the
UT day), G4 conditions are expected on 02-Jun and G1-G2 conditions
are expected on 03-Jun due to an anticipated impact at 2100UT
on 01-Jun +/- 12 hours from a CME first observed on 31-May.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
31 May Normal-fair Normal-fair Fair-poor
PCA Event : 10MeV Proton/PCA Event Began 31 05 2025 1700UT and is in progress
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
01 Jun Poor Poor Poor(PCA)
02 Jun Poor Poor Poor
03 Jun Fair Fair-poor Poor
COMMENT: HF radio propagation conditions on UT day 31-May were
mostly normal to fair, with fair to poor conditions observed
at high latitudes. HF radio propagation conditions are expected
to be degraded at the end of 01-Jun and over 02-Jun, due to an
anticipated CME impact. Conditions are expected to recover slightly
on 03-Jun. Conditions are expected to be poor at high latitudes
on 01-Jun due to an ongoing polar cap absorption event. Shortwave
fadeouts are probable.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
31 May 84
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Depressed by 30% during local night.
Niue Island Region:
No data available during local day.
No data available during local night.
Northern Australian Region:
Near predicted monthly values during local day.
Depressed by 20% during local night.
Southern Australian Region:
Near predicted monthly values during local day.
Depressed by 30% during local night.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 20% over the UT day.
Proton event in progress, increased absorption observed.
Monthly T index:
Month T index
Apr 123
May 113
Jun 111
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
01 Jun 80 15 to 20% below predicted monthly values
02 Jun 60 20 to 30% below predicted monthly values
03 Jun 70 20 to 30% below predicted monthly values
COMMENT: ASWFC Preliminary HF Communications Warning 56 was issued
on 31 May and is current for 2-4 Jun. Maximum usable frequencies
(MUFs) in the Australian region on UT day 31-May were near predicted
monthly values with depressions of up to 30% observed during
local night. Spread F was observed at Hobart, Canberra and Perth
during local night hours. MUFs are expected to be near predicted
monthly values to depressed by up to 20% on 01-Jun. Stronger
depressions are expected over 02-03 Jun due to anticipated geomagnetic
activity beginning in the second half of 01-Jun. Shortwave fadeouts
are probable.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 30 May
Daily Proton Fluence >1 MeV: 2.2E+06
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 1.20E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:12%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.0
DSCOVR Satellite Solar Wind Day Averaged Data for 30 May
Speed: 732 km/sec Density: 1.7 p/cc Temp: 346000 K Bz: 0 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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