[Ips-dsgr] ASWFC Daily Report - 18 March 26 issued 2330 UT on 18 Mar 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Thu Mar 19 10:30:49 AEDT 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 MARCH 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 MARCH AND FORECAST FOR 19 MARCH - 21 MARCH
STATUS INDICATORS SOL:** YELLOW ** MAG:** RED ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 Mar: R1
Flares Max Fadeout Freq. Sectors
M2.7 0842UT possible lower Mid East/Indian
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Mar: 113/64
1B. SOLAR FORECAST
19 Mar 20 Mar 21 Mar
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 115/66 115/66 110/60
COMMENT: Solar activity on UT day 18-Mar was R1 due to an M2.7
flare from AR4392 (S15W05, beta-gamma). This flare was associated
with on disk dimming with plasma motion and was followed by a
coronal mass ejection. The numerous small spots around this regions
large main spot appear to show a mix of growth, decay and redistribution.
Solar region AR4397 (N16E72, beta) is a small region that has
recently rotated onto the solar disk and is slowly growing. There
are currently five numbered sunspot regions on the solar disk.
Other solar regions are small and are either stable or in decay.
Solar activity is expected to be R0-R1 over 19-21 Mar. The CME
associated with the M2.7 flare from region AR4392 had a west
directed component. Event modelling shows an Earth arrival at
20/1700UT +/- 12 hours. S0 solar radiation storm conditions were
observed on UT day 18-Mar. S0 solar radiation storm conditions
are expected over 19-21 Mar. A coronal hole is visible in the
northeast solar quadrant approaching the solar central meridian.
Another coronal hole is visible in the southern solar hemisphere
across the solar central meridian. On UT day 18-Mar the solar
wind speed was moderately enhanced with a declining trend as
the influence of a recent coronal hole wind stream continues
to decline. The solar wind speed ranged from 385 km/s to 440
km/s and is currently at 395 km/s. The peak total interplanetary
field strength (IMF, Bt) was 6 nT. The north-south IMF component
range (Bz) was +4 to -4 nT. Two CME arrivals are now expected.
The first CME is associated with the M2.7 flare on 16-Mar which
is expected to arrive during the second half of the UT day on
19-Mar. The second CME is associated with another M2.7 flare
on 18-Mar and is expected to arrive late in the UT day on 20-Mar.
The second CME has a westward bias and model output shows a potentially
less direct impact than the first CME. Both these flare/CME events
originated from solar region AR4392. In addition, solar wind
27 day recurrent patterns suggest coronal hole wind streams are
likely to increase the solar wind speed over 21-23 Mar.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Mar: G0
Estimated Indices 18 Mar : A K
Australian Region 1 11110001
Cocos Island 0 -1100000
Darwin 1 22000000
Townsville 2 21110001
Learmonth 2 21111001
Alice Springs 1 20010000
Gingin 2 21100001
Canberra 1 01110001
Kennaook Cape Grim 1 11110001
Hobart 1 01110001
Estimated Antarctic Regional K Indices 18 Mar :
Macquarie Island 1 01110000
Casey 8 23332012
Mawson 11 22222115
Observed Regional daily pc3 Indices 18 Mar :
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 Mar : A
Fredericksburg 6
Planetary 7
Observed AFr/Ap Indices 17 Mar : A K
Fredericksburg 4
Planetary 4 2112 1011
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Mar 25 Initially G0, then G1-G2
20 Mar 30 G1-G2
21 Mar 25 G1-G2
COMMENT: ASWFC Geomagnetic Warning 16 was issued on 17 March
and is current for 19-20 Mar. Geomagnetic conditions in the Australian
region on UT day 18-Mar were G0. Conditions in the Antarctic
region were G0. Two CME arrivals are expected over 19-20 Mar,
with the first CME modelled to arrive 19/1800UT +/12 hrs and
the second at 20/1700UT +/- 12hrs. G1-G2 geomagnetic conditions
are expected from late in the UT 19-Mar and continuing into the
first half of 21-Mar. In addition coronal hole wind streams
are expected to contribute to geomagnetic activity over 21-23
Mar.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Mar Normal Normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Mar Normal Normal-fair Fair-poor
20 Mar Normal Fair Fair-poor
21 Mar Normal Fair Fair-poor
COMMENT: HF radio propagation conditions on UT day 18-Mar were
fair to normal. HF radio propagation conditions are expected
to be initially normal on 19-Mar then becoming poor to fair at
middle to high latitudes from late 19-Mar to 21-Mar due to anticipated
geomagnetic activity from two CME arrivals and coronal hole wind
streams.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Mar 87
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Niue Island Region:
Near predicted monthly values during local day.
Depressed by 20% during local night.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Feb 98
Mar 87
Apr 85
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
19 Mar 80 Near predicted monthly values, depressed 15%
late in UT day.
20 Mar 60 Depressed by up to 20%
21 Mar 60 Depressed by up to 20%
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 18-Mar were near predicted monthly values. MUFs
are expected to be near predicted monthly values for most of
the UT day 19-Mar, then becoming 15% depressed late in the UT
day (after local dawn 20-Mar). Australian regional MUFs are expected
to be depressed by up to 20% over 20-21 Mar due to an anticipated
increase in geomagnetic activity from two CME arrivals and coronal
hole wind streams.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Mar
Daily Proton Fluence >1 MeV: 6.6E+05
Daily Proton Fluence >10 MeV: 1.6E+04
Daily Electron Fluence >2 MeV: 8.50E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:10%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B3.5
DSCOVR Satellite Solar Wind Day Averaged Data for 17 Mar
Speed: 463 km/sec Density: 0.7 p/cc Temp: 52700 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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