[Ips-dsgr] ASWFC Daily Report - 20 March 26 issued 2330 UT on 20 Mar 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sat Mar 21 10:30:50 AEDT 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/20 MARCH 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 20 MARCH AND FORECAST FOR 21 MARCH - 23 MARCH
STATUS INDICATORS SOL:GREEN MAG:** RED ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 20 Mar: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Mar: 102/50
1B. SOLAR FORECAST
21 Mar 22 Mar 23 Mar
Activity R0, chance R1 R0, chance R1 R0, chance R1
Fadeouts None expected None expected None expected
10.7cm/SSN 102/50 100/48 100/48
COMMENT: Solar activity on UT day 20-Mar was R0, with no solar
flares. There are currently two numbered sunspot regions on the
solar disk. Active region (AR) 4392 (S15W31, beta) has shown
decay in its trailing spots, and AR 4397 (N16E46, beta) is stable.
Solar activity is generally expected to be R0 with a slight chance
of R1 over 21-13 Mar.
>From 1136 UT on 20-Mar a CME to the northeast can be seen, although
this even is not expected to be geoeffective. Shortly after imagery
shows a weak halo signature, although this is considered an event
on the farside of the Sun and therefore not Earth-directed. No other
CMEs were observed.
S0 solar radiation storm conditions were observed on UT day 20-Mar.
S0 solar radiation storm conditions are expected over 21-23 Mar.
On UT day 20-Mar the solar wind environment disturbed. The solar wind
speed slowly increased, beginning the day near 330 km/s and ending near 500
km/s. The interplanetary magnetic field strength (IMF, Bt) also
increased steadily over the day and peaked at 33 nT. The north-south
IMF component range (Bz) was +19 to -22 nT. The solar wind is
expected to remained disturbed on 21-Mar, with parameters likely
to continue to increase further. The solar wind environment may
begin to return to background levels by 22 or 23 Mar. The source
of the disturbance is the CME from 18-Mar arriving from 20/2016UT
coupled with coronal hole activity. The CME from 16-Mar may have
arrived, but its signature masked from coronal hole effects.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 20 Mar: G0
Estimated Indices 20 Mar : A K
Australian Region 21 23343345
Cocos Island 19 23242345
Darwin - --------
Townsville 25 23353445
Learmonth 30 33353446
Alice Springs 23 23353345
Gingin 24 23342346
Canberra 15 13342334
Kennaook Cape Grim 35 ---44455
Hobart 19 14432335
Estimated Antarctic Regional K Indices 20 Mar :
Macquarie Island 18 13433235
Casey 32 36543335
Mawson 24 23433246
Observed Regional daily pc3 Indices 20 Mar :
Darwin NA
Townsville 19 (Quiet)
Learmonth 13 (Quiet)
Alice Springs 18 (Quiet)
Gingin 22 (Quiet to unsettled)
Canberra 61 (Active)
Hobart 68 (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 20 Mar : A
Fredericksburg 20
Planetary 34
Observed AFr/Ap Indices 19 Mar : A K
Fredericksburg 3
Planetary 3 1111 1100
2B. MAGNETIC FORECAST
Date Ap Conditions
21 Mar 25 G2-G3
22 Mar 20 G1-G2
23 Mar 16 G0-G2
COMMENT: ASWFC Geomagnetic Warning 18 was issued on 20 March
and is current for 21-23 Mar. On UT day 20-Mar geomagnetic activity
in the Australian region was G1. Geomagnetic activity in the
Antarctic region was G0-G2. G2 geomagnetic conditions were reached
on the planetary scale. The CME from 16-Mar may possibly have
arrived although its signature in the solar wind likely masked
by the coronal hole. It is possible the CME from 18-Mar arrived,
as there were multiple sudden impulses detected on 20-Mar, and
a solar wind shock from 20/2016UT. Coronal hole activity is expected
to continue over the next 3 days. Overall, geomagnetic activity
is expected to be G2-G3 on 21-Mar, and G1-G2
on 22-Mar as CME effects subside, and G0-G2 as coronal hole effects
begin to subside.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
20 Mar Normal-fair Normal-fair Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
21 Mar Fair Fair Fair
22 Mar Normal-fair Normal-fair Fair
23 Mar Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 20-Mar were
normal to mildly degraded across the globe. HF radio propagation
conditions are expected to become degraded early on 21-Mar, possibly
recovering by 22-Mar and likely to be mostly normal by 23-Mar.
This is due to the anticipated arrival of a CME from 18-Mar coupled
with coronal hole activity.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
20 Mar 95
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 25% during local day.
Enhanced by 30% during local night.
Niue Island Region:
Near predicted monthly values during local day.
No data available during local night.
Northern Australian Region:
Mostly near predicted monthly values.
Southern Australian Region:
Mostly near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 15% 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
21 Mar 55 Depressed by up to 20%
22 Mar 65 Depressed by up to 20%
23 Mar 80 Near predicted monthly values to 15% depressed
COMMENT: ASWFC Preliminary HF Communications Warning 27 was issued
on 19 March and is current for 20-21 Mar. Maximum usable frequencies
(MUFs) in the Australian region on UT day 20-Mar were near predicted
values. Some spread-F was observed in Hobart during local night
hours. MUFs are expected to become depressed by 20% early on
21-Mar and continue through to 23-Mar but improving on this last
day. Spread-F is possible at middle and high latitudes and scintillation
may be possible in equatorial regions. The source of this activity
is an anticipated CME from 18-Mar coupled with coronal hole activity.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 19 Mar
Daily Proton Fluence >1 MeV: 9.2E+05
Daily Proton Fluence >10 MeV: 1.7E+04
Daily Electron Fluence >2 MeV: 1.60E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:14%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B2.3
DSCOVR Satellite Solar Wind Day Averaged Data for 19 Mar
Speed: 356 km/sec Density: 0.8 p/cc Temp: 42100 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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