[Ips-dsgr] ASWFC Daily Report - 18 April 25 issued 2331 UT on 18 Apr 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sat Apr 19 09:31:07 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 APRIL 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 APRIL AND FORECAST FOR 19 APRIL - 21 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 Apr: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Apr: 156/110
1B. SOLAR FORECAST
19 Apr 20 Apr 21 Apr
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 150/105 150/105 150/105
COMMENT: Solar activity on UT day 18-Apr was R0, with no significant
solar flares. Solar region AR4064 (N10E49, beta-gamma) has shown
slight growth. Solar region AR4062 (S04E32, beta) appears to
be in slow decay with increased separation evident. Small solar
region AR4067 (S02E54, beta) is slightly growing. Other regions
are small and either stable or in decay. There are currently
seven numbered sunspots on the solar disk. A large coronal hole
is visible in the southern solar hemisphere and has started to
cross the solar central meridian, however most of the area of
this hole is below solar latitude S30. Solar activity is expected
to be R0-R1 over 19-21 Apr. S0 solar radiation storm conditions
were observed on 18-Apr. S0 solar radiation storm conditions
are expected over 19-21 Apr. No Earth directed CMEs were observed.
The solar wind environment on UT day 18-Apr was slightly enhanced.
The solar wind speed was steady and ranged from 503 to 418 km/s
and is currently at 418 km/s. The peak total interplanetary field
strength (IMF, Bt) was 12 nT and the north-south IMF component
range was +7 to -10 nT. The solar wind speed is expected to decline
before increasing over 21-22 Apr due to a wind stream from the
southern hemisphere coronal hole.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Apr: G0
Estimated Indices 18 Apr : A K
Australian Region 6 22221222
Cocos Island 4 22110220
Darwin 8 33221222
Townsville 8 32221223
Learmonth 9 33211322
Alice Springs 6 22121222
Gingin 8 23121322
Canberra 6 22121222
Kennaook Cape Grim 8 22222322
Hobart 9 23222322
Estimated Antarctic Regional K Indices 18 Apr :
Macquarie Island 15 23343422
Casey 10 33331122
Mawson 30 35432265
Observed Regional daily pc3 Indices 18 Apr :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 0 (Quiet)
Hobart 0 (Quiet)
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 Apr : A
Fredericksburg 12
Planetary 13
Observed AFr/Ap Indices 17 Apr : A K
Fredericksburg 11
Planetary 11 3422 3212
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Apr 10 G0
20 Apr 8 G0
21 Apr 18 G0-G1
COMMENT: G0 geomagnetic activity was observed in the Australian
region on UT day 18-Apr. In the Antarctic region G0 conditions
were observed at Macquarie Island and Casey, with G1-G2 periods
were observed at Mawson. G0 conditions are expected for 19-20
Apr with G0-G1 conditions expected on 21-22 Apr due to a coronal
hole wind stream.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Apr Normal Fair-normal Fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Apr Normal Normal Normal-fair
20 Apr Normal Normal Normal-fair
21 Apr Normal Normal-fair Fair
COMMENT: On UT day 18-Apr degraded HF conditions were fair to
normal. HF radio propagation conditions are expected to mostly
normal over 19-20 Apr with fair conditions possible on 21-22 Apr
for middle to high latitudes due to mild geomagnetic activity
from a coronal hole wind stream.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Apr 116
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Depressed by 20% during local night.
Niue Island Region:
Enhanced by 25%.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values.
Hobart depressed 15-20% after dawn.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 20% 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
19 Apr 115 Near predicted monthly values
20 Apr 115 Near predicted monthly values
21 Apr 115 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 generally near predicted
monthly values. Spread F was observed during local night hours
at Hobart. MUFs at Hobart were depressed 15-20% after local dawn
this morning and are expected to gradually recover. MUFs are
generally expected near predicted monthly values over 19-21 Apr.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Apr
Daily Proton Fluence >1 MeV: 1.6E+06
Daily Proton Fluence >10 MeV: 1.4E+04
Daily Electron Fluence >2 MeV: 1.20E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 2%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B8.7
DSCOVR Satellite Solar Wind Day Averaged Data for 17 Apr
Speed: 455 km/sec Density: 11.4 p/cc Temp: 45300 K Bz: 9 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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