[Ips-dsgr] ASWFC Daily Report - 18 May 25 issued 2332 UT on 18 May 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Mon May 19 09:32:00 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 MAY 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 MAY AND FORECAST FOR 19 MAY - 21 MAY
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 May: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 May: 118/70
1B. SOLAR FORECAST
19 May 20 May 21 May
Activity R0-R1, chance R2 R0-R1, chance R2 R0-R1, chance R2
Fadeouts Possible Possible Possible
10.7cm/SSN 120/72 118/70 118/70
COMMENT: Solar activity on UT day 18-May was R0, with no significant
solar flares. There are currently four numbered sunspots on the
solar disk, however all of them are either stable or in decay.
Solar activity is expected to be R0-R1 over 19-21 May, with possible
isolated R2 events from the trailing end of AR4087 (N17E03, beta-delta).
No Earth directed CMEs were observed on UT day 18-May.
S0 solar radiation storm conditions were observed on UT day 18-May. Solar
radiation storm conditions are expected over 19-21 May.
The solar wind environment on UT day 18-May was enhanced, with ongoing
coronal hole influence, however the previous day's CME effects
have diminished. The solar wind speed ranged from 823 to 594
km/s and is currently near 600 km/s. The peak total interplanetary
field strength (IMF, Bt) was 12 nT and the north-south IMF component
range (Bz) was +8 to -9 nT. The solar wind is expected to remain
enhanced over 19-21 May, although may be variable as the edge
of the coronal hole may be in and out of range to connect with
Earth due to its latitude.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 May: G0
Estimated Indices 18 May : A K
Australian Region 14 32333432
Cocos Island 9 22322331
Darwin 15 33333432
Townsville 16 32433432
Learmonth 15 33333432
Alice Springs 14 32333432
Gingin 17 33333442
Canberra 16 32433432
Kennaook Cape Grim 19 32444432
Hobart 16 32433432
Estimated Antarctic Regional K Indices 18 May :
Macquarie Island 28 32465432
Casey 21 45432333
Mawson 56 46653375
Observed Regional daily pc3 Indices 18 May :
Darwin 28 (Quiet to unsettled)
Townsville 14 (Quiet)
Learmonth 52 (Unsettled)
Alice Springs 26 (Quiet to unsettled)
Gingin 144 (Severe storm)
Canberra 127 (Severe storm)
Hobart 167 (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 18 May : A
Fredericksburg 17
Planetary 23
Observed AFr/Ap Indices 17 May : A K
Fredericksburg 25
Planetary 38 6535 4443
2B. MAGNETIC FORECAST
Date Ap Conditions
19 May 20 G0-G1
20 May 20 G0, chance G1
21 May 18 G0, chance G1
COMMENT: ASWFC Geomagnetic Warning 38 was issued on 17 May and
is current for 17-19 May. G0 geomagnetic conditions were observed
in the Australian region on UT day 18-May. G1-G3 geomagnetic
conditions were observed in the Antarctic region. An isolated
period of G1 was observed on the planetary geomagnetic scale.
The source of the disturbances was a large coronal hole in the
southern hemisphere. Effects of this coronal hole are expected
to continue over 19-21 May, however may fluctuate as the edge
of the coronal hole may, at times, not be a low enough solar
latitude to connect with Earth.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 May Fair Normal-fair Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 May Normal-fair Normal-fair Normal-fair
20 May Normal-fair Normal-fair Normal-fair
21 May Normal-fair Normal-fair Normal-fair
COMMENT: HF radio propagation conditions on UT day 18-May were
degraded in the northern hemisphere for much of the day. Conditions
were normal to mildly degraded in the southern hemisphere. HF
radio propagation conditions are expected to be fluctuating over
normal to mildly degraded over 19-21 May due to ongoing coronal
hole effects.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 May 94
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Depressed by 20% during local night.
Niue Island Region:
Near predicted monthly values during local day.
Depressed by 30% during local night.
Northern Australian Region:
Depressed by 15% during local day.
Depressed by 15% during local night.
Southern Australian Region:
Mostly near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 30% over the UT day.
Monthly T index:
Month T index
Apr 123
May 113
Jun 111
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
19 May 95 Near predicted values to 15-20% depressed
20 May 95 Near predicted monthly values to 15-20% depressed
21 May 95 Near predicted monthly values to 15-20% depressed
COMMENT: ASWFC HF Communications Warning 48 was issued on 16
May and is current for 17-19 May. ASWFC SWF HF Communications
Warning 49 was issued on 18 May and is current for 18-20 May.
Maximum usable frequencies (MUFs) in the Australian region on
UT day 18-May were near predicted values to 15% depressed. Sporadic-E
was observed in Cocos Islands and Darwin during local night hours.
Spread-F was observed in Hobart. MUFs are expected to be depressed
by 15-20% to near predicted values over 19-21 May due to ongoing
coronal hole effects.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 May
Daily Proton Fluence >1 MeV: 1.2E+06
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: B4.0
DSCOVR Satellite Solar Wind Day Averaged Data for 17 May
Speed: 559 km/sec Density: 5.7 p/cc Temp: 341000 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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