[Ips-dsgr] ASWFC Daily Report - 19 September 25 issued 2330 UT on 19 Sep 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sat Sep 20 09:30:44 AEST 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/19 SEPTEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 19 SEPTEMBER AND FORECAST FOR 20 SEPTEMBER - 22 SEPTEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 19 Sep: R1
Flares Max Fadeout Freq. Sectors
M1.5 2141UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 19 Sep: 160/114
1B. SOLAR FORECAST
20 Sep 21 Sep 22 Sep
Activity R0,chance R1 R0,chance R1 R0,chance R1
Fadeouts Possible Possible Possible
10.7cm/SSN 160/114 160/114 155/109
COMMENT: Solar activity on UT day 19-Sep was at R1-Minor due
to an M1.5 flare at 19/2141UT from solar region AR4216. Solar
region AR4216 (N11W23, beta) is showing decay in its trailer
spots. Solar regions AR4217 (S15E08, beta) and AR4219 (N26W63,
beta) produced sporadic low level C class flare activity. Solar
region AR4220 (S18W24, beta) whilst exhibiting a more complex
and compact spot pattern has been flare quiet. This region has
increased in longitudinal extent, with the umbral area in its
trailer spots initially declining then regrowing. Solar region
AR4223 (S15E24, beta) which has also been flare quiet is currently
growing. There are currently nine numbered sunspot regions on
the solar disk. Most solar regions on the visible solar disk
are small. All other regions are either stable or in decay. Solar
activity is expected to be R0,chance R1 over 20-22 Sep. A solar
prominence eruption was observed from 18/1900UT in GOES SUVI
imagery on the southwest solar limb and is not considered to
be geoeffective. No Earth-directed CMEs have been observed on
UT day 19-Sep up to 19/1724UT. In LASCO C2 and STEREO-A imagery
an eastward behind the solar limb (estimated at E108 degrees)
non Earth directed CME was observed from 18/2312UT. Narrow coronal
streamer activity to the southwest was observed 19/0500-1200UT
in LASCO C2 imagery. S0 solar radiation storm conditions were
observed on UT day 19-Sep. S0 solar radiation storm conditions
are expected over 20-22 Sep. A moderately sized isolated coronal
hole is visible in the northern solar hemisphere currently crossing
the solar central meridian with centre solar latitude at approximately
N25. This hole is larger in area compared to its previous rotation.
The solar wind on UT day 19-Sep continued to slowly decline.
The solar wind speed ranged from 452 km/s to 380 km/s. Currently
the solar wind is 380 km/s. The peak total interplanetary field
strength (IMF, Bt) was 3 nT and the north-south IMF component
range (Bz) was +3 to -1 nT. The magnitude of the IMF has been
very small. The solar wind is expected to be near background
levels over 20-21 Sep. A moderate increase in solar wind speed
is expected from late 22-Sep due to the solar wind stream from
the coronal hole now crossing the solar central meridian. Old
solar region AR4197 is due back to the southeast solar limb on
19-Sep. This region produced an interval R1 flare activity on
its previous disk transit, but was not consistently flare active.
The US GOES geosynchronous satellite 2MeV energy electron detector
has been elevated over the past three days. An elevated 2MeV
electron flux is statistically associated with an increased risk
of geosynchronous satellite anomalies.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 19 Sep: G0
Estimated Indices 19 Sep : A K
Australian Region 1 11000001
Cocos Island 0 11000000
Darwin 2 21100002
Townsville 1 11001011
Learmonth 1 11101000
Alice Springs 1 11000001
Gingin 0 10000000
Canberra 0 00000001
Kennaook Cape Grim 0 00001001
Hobart 0 00001001
Estimated Antarctic Regional K Indices 19 Sep :
Macquarie Island 0 00000000
Casey 4 23220001
Mawson 8 22211034
Observed Regional daily pc3 Indices 19 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 17 (Quiet)
Canberra 11 (Quiet)
Hobart 4 (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 19 Sep : A
Fredericksburg 5
Planetary 4
Observed AFr/Ap Indices 18 Sep : A K
Fredericksburg 6
Planetary 6 2222 2211
2B. MAGNETIC FORECAST
Date Ap Conditions
20 Sep 6 G0
21 Sep 5 G0
22 Sep 17 G0, G1 periods possible late in the UT day
COMMENT: ASWFC Geomagnetic Warning 70 was issued on 19 September
and is current for 22-23 Sep. G0 geomagnetic conditions were
observed in the Australian and Antarctic regions on UT day 19-Sep.
G0 geomagnetic conditions are expected over 20-21 Sep. Periods
of G1 geomagnetic activity are possible from late 22-Sep and
on 23-Sep due to a coronal hole wind stream.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
19 Sep Normal Fair-normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
20 Sep Normal Normal Normal
21 Sep Normal Normal Normal
22 Sep Normal Normal-fair Fair
COMMENT: HF radio propagation conditions on UT day 19-Sep were
mostly normal. HF radio propagation conditions are expected to
be mostly normal over 20-21 Sep. HF conditions at middle to high
latitudes may become mildly degraded from late 22-23 Sep in association
with a mild increase in geomagnetic activity from a coronal hole
wind stream. Isolated minor shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
19 Sep 96
Observed Australian Regional MUFs
Cocos Island Region:
No data available.
Niue Island Region:
Near predicted monthly values during local day.
Enhanced by 25% during local night.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Mostly near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Enhanced by 15% over the UT day.
Monthly T index:
Month T index
Aug 96
Sep 92
Oct 90
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
20 Sep 95 Near predicted monthly values
21 Sep 95 Near predicted monthly values
22 Sep 95 Near predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 19-Sep were mostly near predicted values to
25% enhanced. Spread-F was observed at Hobart during local night
hours. MUFs are expected to be near predicted values over 20-22
Sep. Mildly degraded HF conditions may be experienced during
local night hours for the southern Australian region during 22-23
Sep, due to an anticipated mild increase in geomagnetic activity
from a coronal hole wind stream. Isolated minor shortwave fadeouts
are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 18 Sep
Daily Proton Fluence >1 MeV: 2.0E+06
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 2.90E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:18%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B8.6
DSCOVR Satellite Solar Wind Day Averaged Data for 18 Sep
Speed: 526 km/sec Density: 1.0 p/cc Temp: 73600 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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