[Ips-dsgr] ASWFC Daily Report - 20 August 25 issued 2330 UT on 20 Aug 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Thu Aug 21 09:30:49 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/20 AUGUST 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 20 AUGUST AND FORECAST FOR 21 AUGUST - 23 AUGUST
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 20 Aug: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Aug: 120/72
1B. SOLAR FORECAST
21 Aug 22 Aug 23 Aug
Activity R0, chance R1 R0, chance R1 R0, chance R1
Fadeouts None expected None expected None expected
10.7cm/SSN 120/72 125/78 125/78
COMMENT: Solar activity on UT day 20-Aug was at the R0 level,
with no significant flaring activity. There are currently five
numbered sunspot regions visible on the solar disk. AR4187 (S18W03,
beta) has shown mild growth in its leader spots over the UT day.
AR4189 (N07E35, beta) has exhibited spot growth. Newly numbered
region AR4191 (N10E77, alpha) recently rotated over the eastern
limb and appears stable. AR4190 (N16E55, alpha) recently appeared
on the solar disk and has shown slight growth. All other sunspot
regions are either stable or in decay. Solar activity is expected
to be at the R0 level over 21-23 Aug, with a chance of R1. S0
solar proton conditions were observed on UT day 20-Aug. S0 solar
proton conditions are expected over 21-23 Aug. Several CMEs were
observed, but none are considered geoeffective. A prominence
eruption was observed, visible in GOES SUVI imagery near S30E90
at 20/0424UT. A subsequent associated eastward CME was observed,
visible in LASCO C2 coronagraph imagery from 20/0512UT. Modelling
indicates this CME is not geoeffective. A second prominence eruption
was observed, visible in GOES SUVI imagery near N35E90 at 20/0836UT.
The subsequent associated CME observed at 20/1036UT in LASCO
C2 coronagraph imagery is not considered to be Earth-directed.
The solar wind speed on UT day 20-Aug mildly declined, ranging
from 560 to 670 km/s and is currently near 560 km/s. The peak
total interplanetary magnetic field strength (IMF, Bt) was 8
nT and the north-south IMF component (Bz) range was -8 to +5
nT. The solar wind speed is expected to decline over 21-23 Aug
due to waning coronal hole high speed wind stream effects.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 20 Aug: G0
Estimated Indices 20 Aug : A K
Australian Region 7 32231112
Cocos Island 4 22220111
Darwin 9 33321122
Townsville 10 32331213
Learmonth 7 32221122
Alice Springs 7 32231112
Gingin 9 33231122
Canberra 7 32231112
Kennaook Cape Grim 9 32242112
Hobart 9 32242112
Estimated Antarctic Regional K Indices 20 Aug :
Macquarie Island 11 23342122
Casey 14 44331123
Mawson 50 75533446
Observed Regional daily pc3 Indices 20 Aug :
Darwin 4 (Quiet)
Townsville 0 (Quiet)
Learmonth 4 (Quiet)
Alice Springs 0 (Quiet)
Gingin 53 (Unsettled)
Canberra 37 (Quiet to unsettled)
Hobart 74 (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 Aug : A
Fredericksburg 15
Planetary 16
Observed AFr/Ap Indices 19 Aug : A K
Fredericksburg 19
Planetary 0 3223 4454
2B. MAGNETIC FORECAST
Date Ap Conditions
21 Aug 12 G0, chance of G1
22 Aug 8 G0
23 Aug 8 G0
COMMENT: G0 geomagnetic conditions were observed in the Australian
region on UT day 20-Aug. Mostly G0-G1 geomagnetic conditions
were observed in the Antarctic region, with an isolated period
of G2 and an isolated period of G3 observed at Mawson. G0 geomagnetic
conditions are expected over 21-23 Aug, with a chance of G1 on
21-Aug due to ongoing high speed solar wind conditions from an
equatorial coronal hole.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
20 Aug Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
21 Aug Normal Normal Normal-fair
22 Aug Normal Normal Normal-fair
23 Aug Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 20-Aug were
mostly normal. HF radio propagation conditions are expected to
be mostly normal over 21-23 Aug, with fair conditions possible
at high latitudes.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
20 Aug 107
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 15% during local day.
Depressed by 35% during local night.
Niue Island Region:
Near predicted monthly values during local day.
Enhanced by 25% during local night.
Northern Australian Region:
Enhanced by 15% during local day.
Near predicted monthly values during local night.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 20% over the UT day.
Monthly T index:
Month T index
Jul 88
Aug 96
Sep 93
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
21 Aug 95 Near predicted monthly values
22 Aug 95 Near predicted monthly values
23 Aug 95 Near predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 20-Aug were mostly near predicted monthly values,
with some enhancements observed in the northern Australian region
during local day hours. Spread F was observed at Hobart during
local night hours. MUFs are expected to be near predicted monthly
values over 21-23 Aug.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 19 Aug
Daily Proton Fluence >1 MeV: 9.2E+05
Daily Proton Fluence >10 MeV: 1.5E+04
Daily Electron Fluence >2 MeV: 1.60E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B6.3
DSCOVR Satellite Solar Wind Day Averaged Data for 19 Aug
Speed: 447 km/sec Density: 5.2 p/cc Temp: 215000 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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