[Ips-dsgr] ASWFC Daily Report - 15 April 25 issued 2331 UT on 15 Apr 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Wed Apr 16 09:31:13 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/15 APRIL 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 15 APRIL AND FORECAST FOR 16 APRIL - 18 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:** RED ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 15 Apr: R1
Flares Max Fadeout Freq. Sectors
M1.5 1020UT possible lower European
M1.3 1814UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 15 Apr: 153/108
1B. SOLAR FORECAST
16 Apr 17 Apr 18 Apr
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 160/114 160/114 155/109
COMMENT: Solar activity on UT day 15-Apr was at the R1 level.
The two M1 class flares were from solar region AR4055 from behind
the northwest solar limb. Solar region AR4060 (N09W01, beta-gamma)
continued to show decay in its leader spots with some redistribution
in its trailer spots. The more complex magnetic field in the trailer
spots is weak. Solar region AR4062 (S02E71, beta) has shown growth.
Other regions are minor. A very small spot may be emerging to
the east of AR4062. A new tiny spot is emerging on disk at N03E23,
colocated with a solar filament in the chromosphere which is
dividing. There are currently four numbered sunspot regions on
the visible on the solar disk. All other sunspot groups were
either stable or in decay. Solar activity is expected to be at
the R0-R1 level over 16-18 Apr. S0 solar radiation storm conditions
were observed on UT day 15-Apr. S0 solar radiation storm conditions
are expected over 16-18 Apr. No Earth directed CMEs have been
observed on 15-Apr. Two very narrow non-Earth directed CMEs were
observed, with the first to the east from 15/1524UT and the second
to the south from 15/1600UT. The solar wind speed on UT day 15-Apr
was initially slow and steady before a moderate solar wind shock
was observed at 15/1637UT with the solar wind speed subsequently
increasing to approximately 500km/sec immediately after the shock.
The solar wind parameters then became strongly enhanced. The
wind speed mostly ranged between 369 km/s and 571 km/s. The current
wind speed is around 570 km/s. The peak total interplanetary
field strength (IMF, Bt) was 27 nT and the north-south IMF component
range (Bz) was +19 to -21 nT. Post shock arrival the enhanced
IMF Bz component was briefly strongly southward during the interval
15/1831-1839UT and fluctuated southward during the interval 15/2030-2130UT.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 15 Apr: G1
Estimated Indices 15 Apr : A K
Australian Region 14 22112345
Cocos Island 13 12111345
Darwin 16 22211445
Townsville 14 22122444
Learmonth 15 22122345
Alice Springs 15 22111445
Gingin 20 22111356
Canberra 10 22112334
Kennaook Cape Grim - --------
Hobart 13 22112335
Estimated Antarctic Regional K Indices 15 Apr :
Macquarie Island 13 12234333
Casey 22 33321455
Mawson 50 43322558
Observed Regional daily pc3 Indices 15 Apr :
Darwin 9 (Quiet)
Townsville 6 (Quiet)
Learmonth 14 (Quiet)
Alice Springs 7 (Quiet)
Gingin 17 (Quiet)
Canberra 24 (Quiet to unsettled)
Hobart 32 (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 15 Apr : A
Fredericksburg 12
Planetary 15
Observed AFr/Ap Indices 14 Apr : A K
Fredericksburg 0
Planetary 0 3532 2322
2B. MAGNETIC FORECAST
Date Ap Conditions
16 Apr 30 G1-G2
17 Apr 16 G1 early in UT day , declining to G0
18 Apr 12 G0
COMMENT: ASWFC Geomagnetic Warning 29 was issued on 15 April
and is current for 15-17 Apr. G1 geomagnetic conditions were
observed in the Australian region on UT day 15-Apr. A weak sudden
impulse was observed in regional magnetometers at 15/1722UT due
to the arrival of a CME. A mild increase in geomagnetic activity
was observed after the impulse. The planetary geomagnetic field
reached G2 after the CME arrival. In the Antarctic region G0
conditions were observed at Macquarie Island, G1 conditions at
Casey and G4 conditions at Mawson. The Bureau Dst index has so
far remained positive post shock arrival, possibly indicating
reduced geomagnetic storm activity, however the Dst index may
subsequently become negative during 16-Apr.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
15 Apr Normal Normal-poor Normal-poor
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
16 Apr Normal Poor-fair Poor
17 Apr Normal Fair-normal Fair
18 Apr Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 15-Apr were
normal to poor, with fair to poor conditions at middle to high
latitudes late in the UT day. Degraded HF conditions for middle
to high latitudes are expected for 16-Apr due to ongoing geomagnetic
activity induced by a CME.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
15 Apr 112
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values.
Niue Island Region:
Enhanced by 25% during local day.
Near predicted monthly values during local night.
Northern Australian Region:
Mostly near predicted monthly values.
Enhanced by 20% after local dawn.
Southern Australian Region:
Near predicted monthly values.
Depressed 15-20% pre-dawn period.
Depressed 10-15% after local dawn.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 15% 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
16 Apr 95 Depressed 15 to 20%/near predicted monthly values
17 Apr 105 Depressed 10 to 15%/near predicted monthly values
18 Apr 115 Near predicted monthly values
COMMENT: ASWFC Preliminary HF Communications Warning 38 was issued
on 15 April and is current for 16-17 Apr. Maximum usable frequencies
(MUFs) in the Australian region on UT day 16-Apr were generally
near predicted values with depressions of 15-20% observed after
local dawn for the southeast Australian region. Spread-F was
observed during pre-dawn hours at Perth and Hobart. The Australian
region ionospheric response to ongoing geomagnetic activity has
been limited to depressions of up to 20% during the predawn period,
with Hobart and Canberra only mildly depressed by 15% after dawn
this morning. MUFs are expected to be depressed 15-20% at times
for the southern Australian region on 16-Apr. Northern Australian
region MUFs are mostly expected to remain near normal.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 14 Apr
Daily Proton Fluence >1 MeV: 5.8E+05
Daily Proton Fluence >10 MeV: 1.5E+04
Daily Electron Fluence >2 MeV: 5.60E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 7%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.8
DSCOVR Satellite Solar Wind Day Averaged Data for 14 Apr
Speed: 424 km/sec Density: 2.0 p/cc Temp: 73300 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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