[Ips-dsgr] ASWFC Daily Report - 21 April 25 issued 2330 UT on 21 Apr 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Tue Apr 22 09:30:56 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/21 APRIL 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 21 APRIL AND FORECAST FOR 22 APRIL - 24 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 21 Apr: R1
Flares Max Fadeout Freq. Sectors
M1.9 1837UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 21 Apr: 163/117
1B. SOLAR FORECAST
22 Apr 23 Apr 24 Apr
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 163/117 160/114 160/114
COMMENT: Solar activity on UT day 21-Apr was R1, with an isolated
M1.9 solar flare from AR4062 (S03W16, beta). There are currently
seven numbered sunspot regions on the solar disk. All sunspots
are currently stable, with none showing any significant growth
in th e past day. Solar activity is expected to be R0-R1 over
22-24 Apr.
No Earth directed CMEs have been observed in the past
24 hours, although several non-Earth directed CMEs were observed
from a region on the western solar limb.
S0 solar radiation storm conditions were observed on UT day 21-Apr.
S0 solar radiation storm conditions are expected over 22-24 Apr.
The solar wind on UT day 21-Apr was mildly disturbed, possibly due to a
co-rotating
interaction region ahead of the large coronal hole in the southern
solar hemisphere, or else the arrival of this coronal hole. The
peak total interplanetary field strength (IMF, Bt) was 18 nT
and the north-south IMF component range (Bz) was +10 to -13 nT.
The solar wind speed showed a notable increase from 0600 UT onwards,
and ranged from 420 to 735 km/s. The solar wind environment is
expected to continue to be disturbed over 22-24 Apr due to the
large coronal hole in the southern hemisphere.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 21 Apr: G0
Estimated Indices 21 Apr : A K
Australian Region 18 33444332
Cocos Island 14 22434331
Darwin 19 33444333
Townsville 17 33444322
Learmonth 20 32454332
Alice Springs 17 33444232
Gingin 17 32444332
Canberra 16 33443322
Kennaook Cape Grim 17 33443332
Hobart 18 33443333
Estimated Antarctic Regional K Indices 21 Apr :
Macquarie Island 37 33465553
Casey 19 44433333
Mawson 44 44544573
Observed Regional daily pc3 Indices 21 Apr :
Darwin 4 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 17 (Quiet)
Canberra 19 (Quiet)
Hobart 66 (Active)
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 21 Apr : A
Fredericksburg 28
Planetary 39
Observed AFr/Ap Indices 20 Apr : A K
Fredericksburg 14
Planetary 0 ---- ----
2B. MAGNETIC FORECAST
Date Ap Conditions
22 Apr 20 G1-G2
23 Apr 25 G1-G2
24 Apr 25 G1-G2
COMMENT: ASWFC Geomagnetic Warning 33 was issued on 18 April
and is current for 21-22 Apr. G0 geomagnetic conditions were
observed in the Australian region on UT day 21-Apr. G0-G3 geomagnetic
conditions were observed in the Antarctic region, and G0-G1 geomagnetic
conditions were observed on the planetary scale. G1-G2 geomagnetic
conditions are expected over 22-24 Apr due to a large coronal
hole in the southern solar hemisphere. This feature has already
connected to Earth with strong solar wind speeds and is expected
to remain connected with Earth for several days.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
21 Apr Normal-fair Normal-fair Fair-poor
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
22 Apr Normal-fair Fair Fair-poor
23 Apr Normal-fair Fair Fair-poor
24 Apr Normal-fair Fair Fair-poor
COMMENT: On UT day 21-Apr HF radio propagation conditions were
normal to fair in the first half of the day, then degradations
began setting in by the latter half to all latitudes. HF radio
propagation conditions are expected to be degraded over 22-24
Apr, particularly during local night hours and particularly for
high latitudes. The cause for the degradations is a large coronal
hole in the southern solar hemisphere.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
21 Apr 105
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values.
Niue Island Region:
Near predicted monthly values during local day.
Depressed by 20% during local night.
Northern Australian Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Southern Australian Region:
Near predicted monthly values during local day.
Depressed by 20% during local night.
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
22 Apr 100 10 to 20% below predicted monthly values
23 Apr 90 15 to 25% below predicted monthly values
24 Apr 85 15 to 25% below predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 21-Apr were near predicted values to 20% depressed.
Sporadic-E was observed in the Cocos Islands during local night
hours. MUFs are expected to be depressed 10-25% over 22-24 Apr
due to coronal hole activity. Spread-F is expected over local
night hours.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 20 Apr
Daily Proton Fluence >1 MeV: 3.1E+05
Daily Proton Fluence >10 MeV: 1.5E+04
Daily Electron Fluence >2 MeV: 2.30E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 4%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.0
DSCOVR Satellite Solar Wind Day Averaged Data for 20 Apr
Speed: 394 km/sec Density: 5.9 p/cc Temp: 87600 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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