[Ips-dsgr] ASWFC Daily Report - 19 April 25 issued 2330 UT on 19 Apr 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sun Apr 20 09:30:43 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/19 APRIL 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 19 APRIL AND FORECAST FOR 20 APRIL - 22 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 19 Apr: R0
Flares Max Fadeout Freq. Sectors
M4.4 18/2350UT possible lower West Pacific
Observed 10.7 cm flux/Equivalent Sunspot Number for 19 Apr: 157/111
1B. SOLAR FORECAST
20 Apr 21 Apr 22 Apr
Activity R0-R1 R1 R1
Fadeouts Possible Possible Possible
10.7cm/SSN 160/114 165/119 165/119
COMMENT: Solar activity on UT day 19-Apr was R0. An R1 M4.4 flare
was observed yesterday late in the UT day from just behind the
southeast solar limb at solar latitude S28. Solar region AR4062
(S04E19, beta) and AR4064 (N03E37, beta) are medium sized and
the larger of the on disk regions. Both these regions have been
relatively quiet, with solar region AR4062 showing decay and
AR4064 showing redistribution in its trailer spots. Small solar
region AR4060 (N07W53, beta) produced a minor C1 flare at 19/1114UT.
Small solar region AR4065 (S30E39, beta) shows some growth in
its trailer spots. There are currently seven numbered sunspots
on the solar disk, other regions are small with simple magnetic
configurations. Some plasma emission is visible at solar latitudes
S28 and N15 on the eastern solar limb suggesting solar regions
may soon rotate onto the solar disk at these latitudes. A 15
degree long section of a solar filament located at N25E20 slowly
lifted off over 19/1200-1500UT and a 10 degree long filament
located at S05W25 is showing motion in GONG H-alpha imagery.
A large coronal hole is visible in the southern solar hemisphere
and is transiting the solar central meridian. Solar activity
is expected to be R0-R1 on 20-Apr and R1 on 21-22 Apr. S0 solar
radiation storm conditions were observed on 19-Apr. S0 solar
radiation storm conditions are expected over 20-22 Apr. No Earth
directed CMEs were observed. Yesterday's M4.4 flare on the southeast
solar limb was associated with a steeply southeast directed CME
and has been modelled as an Earth miss. A directly southward
CME was observed from 19/1700UT and from event timing may possibly
be associated with the filament lift off in the northeast solar
quadrant, however it is directly steeply southward out of the
ecliptic plane. This low confidence pairing has been modelled
as an Earth miss. The solar wind speed slowly declined and ranged
from 409 to 370 km/s and is currently at 370 km/s. The peak total
interplanetary field strength (IMF, Bt) was 9 nT and the north-south
IMF component range was +4 to -8 nT. The IMF Bz component was
mildly southward during the second half of the UT day. The solar
wind speed is expected to decline before increasing to moderate
to strong over 21-22 Apr due to a wind stream from the southern
hemisphere coronal hole. The solar wind may then stay elevated
for 3-4 days.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 19 Apr: G0
Estimated Indices 19 Apr : A K
Australian Region 11 22333322
Cocos Island 7 22223212
Darwin 10 22332223
Townsville 11 22333322
Learmonth 13 22343323
Alice Springs 10 22333222
Gingin 13 22343323
Canberra 14 22443322
Kennaook Cape Grim 14 22443322
Hobart 16 22443333
Estimated Antarctic Regional K Indices 19 Apr :
Macquarie Island 35 33665432
Casey 12 34332212
Mawson 41 64434465
Observed Regional daily pc3 Indices 19 Apr :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 2 (Quiet)
Alice Springs 0 (Quiet)
Gingin 3 (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 19 Apr : A
Fredericksburg 16
Planetary 17
Observed AFr/Ap Indices 18 Apr : A K
Fredericksburg 11
Planetary 13 3432 2223
2B. MAGNETIC FORECAST
Date Ap Conditions
20 Apr 8 G0
21 Apr 18 G0-G1
22 Apr 22 G1, chance G2
COMMENT: ASWFC Geomagnetic Warning 33 was issued on 18 April
and is current for 21-22 Apr. G0 geomagnetic activity was observed
in the Australian region on UT day 19-Apr. In the Antarctic region
G0 conditions were observed at Casey, with G1-G2 periods were
observed at Macquarie Island and Mawson. G0 conditions are expected
for 20 Apr with G0-G1, chance G2 conditions expected during 21-22
Apr due to the anticipated Earth entry into a coronal hole wind
stream.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
19 Apr Normal Fair-normal Fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
20 Apr Normal Normal Normal-fair
21 Apr Normal Normal-fair Fair
22 Apr Normal Normal-fair Fair
COMMENT: On UT day 19-Apr degraded HF conditions were fair to
normal. HF radio propagation conditions are expected to mostly
normal over 20 Apr with fair conditions possible on 21-22 Apr
for middle to high latitudes due to expected geomagnetic activity
from a coronal hole wind stream.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
19 Apr 121
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 40% during local day.
Enhanced by 25% during local night.
Niue Island Region:
Near predicted monthly values during local day.
Depressed by 25% during local night.
Enhanced by 20% after local dawn.
Northern Australian Region:
Mostly near predicted monthly values.
Enhanced by 20% after local dawn.
Southern Australian Region:
Near predicted monthly values.
Hobart 15-25% depressed 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
20 Apr 120 Near predicted monthly values
21 Apr 120 Near predicted monthly values
22 Apr 100 10 to 15% below predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 19-Apr were generally near predicted monthly
values. Spread F was observed during local night hours at Hobart.
MUFs at Hobart were depressed 15-25% after local dawn and northern
region MUFs were 15% enhanced after local dawn this morning.
MUFs are generally expected to be near predicted monthly values over
20-22 Apr. Hobart MUFs are expected to gradually recover. Southern
Australian region HF conditions may become degraded from 22-Apr.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 18 Apr
Daily Proton Fluence >1 MeV: 1.7E+05
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 18 Apr
Speed: 433 km/sec Density: 2.8 p/cc Temp: 97500 K Bz: -1 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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