[Ips-dsgr] ASWFC Daily Report - 17 April 25 issued 2331 UT on 17 Apr 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Fri Apr 18 09:31:19 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/17 APRIL 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 17 APRIL AND FORECAST FOR 18 APRIL - 20 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 17 Apr: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 17 Apr: 151/106
1B. SOLAR FORECAST
18 Apr 19 Apr 20 Apr
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 150/105 148/102 148/102
COMMENT: Solar activity on UT day 17-Apr was R0, with no significant
solar flares. There are currently five numbered sunspots on the
solar disk. AR4062 (S04E43, beta) is the largest spot, however
its positive polarity seems to be weakening, leaving only the
negative polarity dominating. Otherwise, all other sunspot regions
are either stable or in decay. Solar activity is expected to
be R0-R1 over 18-20 Apr.
Several narrow CMEs were observed on UT day 17-Apr but none are considered
geoeffective.
S0 solar radiation storm conditions were observed on UT day 17-Apr.
S0 solar radiation storm conditions are expected over 17-19 Apr.
The solar wind environment on UT day 17-Apr was disturbed due
to residual CME influences, and possibly connection to a small
coronal hole. The solar wind speed ranged from 523 to 428 km/s,
currently on a declining trend. The peak total interplanetary
field strength (IMF, Bt) was 16 nT and the north-south IMF component
range was +13 to -1 nT, with no significant periods of southward
Bz. The solar wind may remain slightly enhanced on 18-Apr due
to the small coronal hole, but on a general declining trend over
19-20 Apr.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 17 Apr: G0
Estimated Indices 17 Apr : A K
Australian Region 9 24213202
Cocos Island 9 34213201
Darwin 14 35213213
Townsville 13 35223211
Learmonth 12 35213202
Alice Springs 11 25213202
Gingin 5 23112102
Canberra 6 24112101
Kennaook Cape Grim 6 24112101
Hobart 6 24112101
Estimated Antarctic Regional K Indices 17 Apr :
Macquarie Island 8 25112001
Casey 13 35322112
Mawson 18 25214115
Observed Regional daily pc3 Indices 17 Apr :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 11 (Quiet)
Canberra 11 (Quiet)
Hobart 26 (Quiet to 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 17 Apr : A
Fredericksburg 10
Planetary 11
Observed AFr/Ap Indices 16 Apr : A K
Fredericksburg 43
Planetary 77 5335 7685
2B. MAGNETIC FORECAST
Date Ap Conditions
18 Apr 16 G0, chance G1
19 Apr 10 G0
20 Apr 8 G0
COMMENT: ASWFC Geomagnetic Warning 32 was issued on 17 April
and is current for 17-18 Apr. G0 geomagnetic activity was observed
in the Australian region on UT day 17-Apr. G0-G1 geomagnetic
activity was observed in the Antarctic region. Mostly G0 geomagnetic
conditions are expected over 18-20 Apr, although a small chance
for G1 remains on 18-Apr in the event there is any southward
Bz before the solar wind returns to background levels.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
17 Apr Normal-fair Fair Fair-poor
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
18 Apr Normal-fair Normal-fair Fair
19 Apr Normal Normal-fair Normal-fair
20 Apr Normal Normal Normal
COMMENT: On UT day 17-Apr degraded HF propagation conditions
were observed across the globe, especially in the northern hemisphere
and at high latitudes. HF radio propagation conditions are expected
to begin improving on 18-Apr, returning to normal over 19-20
Apr.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
17 Apr 99
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 20% during local day.
Enhanced by 35% during local night.
Niue Island Region:
Near predicted monthly values.
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.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 25% over the UT day.
Monthly T index:
Month T index
Mar 126
Apr 115
May 113
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
18 Apr 105 Depressed 10 to 20%/near predicted monthly values
19 Apr 115 Depressed 10 to 20%/near predicted monthly values
20 Apr 120 Near predicted monthly values
COMMENT: ASWFC HF Communications Warning 40 was issued on 16
April and is current for 17-19 Apr. Maximum usable frequencies
(MUFs) in the Australian region were depressed by 30% in the
southern region, but near predicted values to 15% enhanced in
the northern region. Despite geomagnetic storm activity the day
prior, HF conditions were generally non-degraded throughout the
local day and night. MUFs are expected to be depressed by 10-20%
over 18-19 Apr, on an improving trend, and near predicted values
by 20-Apr.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 16 Apr
Daily Proton Fluence >1 MeV: 3.3E+06
Daily Proton Fluence >10 MeV: 1.4E+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: C1.0
DSCOVR Satellite Solar Wind Day Averaged Data for 16 Apr
Speed: 512 km/sec Density: 13.7 p/cc Temp: 105000 K Bz: 5 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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