[Ips-dsgr] ASWFC Daily Report - 25 September 23 issued 2330 UT on 25 Sep 2023 [SEC=OFFICIAL]
Regional Warning Centre
rwc at ips.gov.au
Tue Sep 26 09:30:51 EST 2023
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/25 SEPTEMBER 2023
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 25 SEPTEMBER AND FORECAST FOR 26 SEPTEMBER - 28 SEPTEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 25 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 25 Sep: 170/124
1B. SOLAR FORECAST
26 Sep 27 Sep 28 Sep
Activity R1-R2 R1-R2 R1-R2
Fadeouts Possible Possible Possible
10.7cm/SSN 166/120 164/118 164/118
COMMENT: Solar activity on UT day 25-Sep was at the R0 level.
The three most notable regions on the solar disk are AR3435(N10W34,
beta), AR3445(S13W01, beta) and AR3433(N28W77, beta). Solar region
AR3445 showed growth in a northern spot within this region. Solar
region AR3445, which consists of numerous small spots showed
both growth and decay, though maybe in overall decline. Solar
region AR3443 is approaching the north west solar limb. A new
region AR3447(S22E14, beta) is currently showing rapid growth.
There are currently 10 numbered regions on the solar disk. Other
solar regions are small. Solar activity over 26-28 Sep is expected
to be R1, with the chance of an R2 flare. The 10MeV solar proton
flux was S0, with very mildly enhanced flux (0.7PFU) at the start
of the UT day on 25-Sep. A 15 degree long solar filament located
at N25W55 erupted at 25/1537UT (GONG H-alpha imagery). The far
western longitude location will probably reduce geo-effectiveness
of any possibly associated CME. No significantly Earth directed
CMEs have been observed, however available LASCO imagery is only
up to 25/1018UT. CMEs were observed in the second half of the
UT day 24-Sep to the north west and west but could not be correlated
to on disk activity. The solar wind parameters have been recently
enhanced due to the arrival of a recent CME and are currently
declining as the influence of the CME transient abates. The solar
wind speed on UT day 25-Sep was moderately elevated, ranging
from 419 km/s to 508 km/s and is currently near 450 km/s. The
peak total interplanetary field strength (IMF, Bt) was 34 nT
and the north-south IMF component range was +33 to -19 nT. The
solar wind IMF was strongly enhanced following the CME arrival
late on 24-Sep. The IMF Bz orientation became predominately northward
after 25/0400UT, reducing induced geomagnetic activity. Further
weak solar wind enhancements may occur on 25-Sep due to possible
glancing impacts from CMEs first observed on 22-Sep. A decline
towards background levels is possible on 27-Sep.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 25 Sep: G0, with isolated
G1 periods at some sites
Estimated Indices 25 Sep : A K
Australian Region 18 44434222
Cocos Island 16 44433222
Darwin 19 44434223
Townsville 25 44544333
Learmonth 26 54544332
Alice Springs 20 44534222
Gingin 19 54433222
Canberra 18 44434222
Hobart 16 44433222
Estimated Antarctic Regional K Indices 25 Sep :
Macquarie Island 15 34343222
Casey 34 56643223
Mawson 24 55433333
Observed Regional daily pc3 Indices 25 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 14 (Quiet)
Canberra 6 (Quiet)
Hobart 15 (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 25 Sep : A
Fredericksburg 19
Planetary 26
Observed AFr/Ap Indices 24 Sep : A K
Fredericksburg 17
Planetary 24 2132 3366
2B. MAGNETIC FORECAST
Date Ap Conditions
26 Sep 17 G0, chance of G1
27 Sep 11 G0
28 Sep 8 G0
COMMENT: ASWFC Geomagnetic Warning 58 was issued on 24 September
and is current for 25-27 Sep. G0, with isolated G1 periods at
some sites were observed in the Australian region on UT day 25-Sep.
In the Antarctic region G0 conditions were observed at Macquarie
Island, G1-G2 conditions at Casey and G1 periods were observed
at Mawson. G0 geomagnetic conditions are generally expected for
today, with the chance of G1 periods, due to the possible arrival
of further glancing impacts from CMEs first observed on 22-Sep.
G0 conditions are expected on 27-Sep.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
25 Sep Normal Normal Poor-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
26 Sep Normal Fair-normal Fair
27 Sep Normal Normal Normal-fair
28 Sep Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 25-Sep were
moderately degraded at middle to high latitudes particularly
during local night hours. Mostly normal HF propagation conditions
are expected over 26-28 Sep. Shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
25 Sep 105
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values.
Niue Island Region:
Enhanced by 20% during local day.
Near predicted monthly values during local night.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Depressed by 15% during local day.
Near predicted monthly values during local night.
Enhanced by 45% after local dawn.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 40% over the UT day.
Monthly T index:
Month T index
Aug 115
Sep 96
Oct 93
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
26 Sep 100 Near predicted monthly values
27 Sep 100 Near predicted monthly values
28 Sep 100 Near predicted monthly values
COMMENT: ASWFC SWF HF Communications Warning 100 was issued on
24 September and is current for 25-27 Sep. ASWFC Preliminary
HF Communications Warning 101 was issued on 25 September and
is current for 25-26 Sep. Maximum usable frequencies (MUFs) in
the Australian region on UT day 25-Sep were depressed by 15%
in the southern Australian region and near predicted values in
the northern Australian region. Spread-F was observed at Hobart
and Perth during local night hours. Hobart MUFs were enhanced
by 20% after local dawn this morning. MUFs are expected to be
near monthly predicted values over 26-28 Sep. Shortwave fadeouts
are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 24 Sep
Daily Proton Fluence >1 MeV: 2.9E+07
Daily Proton Fluence >10 MeV: 4.5E+04
Daily Electron Fluence >2 MeV: 1.40E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.5
DSCOVR Satellite Solar Wind Day Averaged Data for 24 Sep
Speed: 315 km/sec Density: 1.5 p/cc Temp: 18100 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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