[Ips-dsgr] ASWFC Daily Report - 21 May 25 issued 2331 UT on 21 May 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Thu May 22 09:31:11 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/21 MAY 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 21 MAY AND FORECAST FOR 22 MAY - 24 MAY
STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 21 May: R1
Flares Max Fadeout Freq. Sectors
M1.2 0008UT possible lower West Pacific
Observed 10.7 cm flux/Equivalent Sunspot Number for 21 May: 119/71
1B. SOLAR FORECAST
22 May 23 May 24 May
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 120/72 122/75 122/75
COMMENT: Solar activity on UT day 21-May was at the R1 level,
due to an M1.2 flare at 21/0008UT. There were no other flare
events above the R0 level throughout the day. There are currently
seven numbered sunspot regions visible on the solar disk. AR4087
(N17W37, beta) is the largest region on the solar disk and was
responsible for the M1.2 flare of the day. This region has reduced
in magnetic complexity recently. AR4095 (S05W56, beta-gamma-delta)
showed spot development over the UT day and has increased in
magnetic complexity. All other sunspot regions are either stable
or in decay. Solar activity is expected to be at R0-R1 levels
over 22-24 May. S0 solar radiation conditions were observed on
21-May. S0 conditions are expected over 22-24 May. No Earth-directed
CMEs have been observed. A southwest directed CME is visible
in SOHO and STEREO-A imagery from 21/1424UT. This event is from
the far side of the Sun and is not geoeffective. The solar wind
speed on UT day 21-May was steady and elevated due to coronal
hole high speed wind stream effects, with a slight decline at
the end of the day. The speed mostly ranged between 540 to 670
km/s and is currently near 550 km/s. The peak total interplanetary
magnetic field strength (IMF, Bt) was 9 nT and the north-south
IMF component (Bz) range was -6 to +7 nT. The solar wind speed
is expected to remain elevated over 22-24 May due to ongoing
coronal hole high speed wind stream effects from a large coronal
hole in the southern hemisphere.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 21 May: G0
Estimated Indices 21 May : A K
Australian Region 6 22321111
Cocos Island 5 22320011
Darwin 8 32321122
Townsville 7 22321122
Learmonth 9 32331122
Alice Springs 6 22321111
Gingin 7 32321121
Canberra 6 22321111
Kennaook Cape Grim 7 32321111
Hobart 6 22321111
Estimated Antarctic Regional K Indices 21 May :
Macquarie Island 8 22431101
Casey 11 43322113
Mawson 44 74643235
Observed Regional daily pc3 Indices 21 May :
Darwin 6 (Quiet)
Townsville 0 (Quiet)
Learmonth 7 (Quiet)
Alice Springs 2 (Quiet)
Gingin 43 (Unsettled)
Canberra 58 (Unsettled)
Hobart 71 (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 May : A
Fredericksburg 12
Planetary 12
Observed AFr/Ap Indices 20 May : A K
Fredericksburg 0
Planetary 0 2333 3323
2B. MAGNETIC FORECAST
Date Ap Conditions
22 May 12 G0, chance of G1
23 May 10 G0
24 May 10 G0
COMMENT: G0 geomagnetic conditions were observed in the Australian
region on UT day 21-May. Mostly G0 geomagnetic conditions were
observed in the Antarctic region, with isolated periods of G1-G3
observed at Mawson. G0 geomagnetic conditions are expected over
22-24 May, with a chance of G1 on 22-May due to ongoing coronal
hole high speed wind stream effects from a large coronal hole
in the southern hemisphere.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
21 May Normal-fair Normal-fair Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
22 May Normal Normal Normal-fair
23 May Normal Normal Normal-fair
24 May Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 21-May were
mostly normal to fair with poorer conditions in the northern
hemisphere. HF radio propagation conditions are expected to be
normal to fair over 22-24 May with conditions slowly improving
over the period, due to ongoing coronal hole effects. Shortwave
fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
21 May 96
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Depressed by 25% during local night.
Niue Island Region:
Near predicted monthly values during local day.
Depressed by 25% during local night.
Northern Australian Region:
Near predicted monthly values during local day.
Depressed by 30% during local night.
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
Apr 123
May 113
Jun 111
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
22 May 90 Depressed 15%/near predicted monthly values
23 May 90 Depressed 15%/near predicted monthly values
24 May 90 Depressed 15%/near predicted monthly values
COMMENT: ASWFC SWF HF Communications Warning 50 was issued on
21 May and is current for 21-23 May. Maximum usable frequencies
(MUFs) in the Australian region on UT day 21-May were near predicted
monthly values during local day with depressions of up to 30%
observed in the northern Australian region. Spread F and sporadic
E was observed at Hobart during local night hours and light sporadic
E was observed at Brisbane. MUFs are expected to be near predicted
monthly values to 15% depressed over 22-24 May. Shortwave fadeouts
are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 20 May
Daily Proton Fluence >1 MeV: 6.4E+05
Daily Proton Fluence >10 MeV: 1.6E+04
Daily Electron Fluence >2 MeV: 3.80E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 6%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B5.3
DSCOVR Satellite Solar Wind Day Averaged Data for 20 May
Speed: 527 km/sec Density: 2.7 p/cc Temp: 214000 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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