[Ips-dsgr] ASWFC Daily Report - 17 September 23 issued 2334 UT on 17 Sep 2023 [SEC=OFFICIAL]
rwc
rwc at ips.gov.au
Mon Sep 18 09:34:18 EST 2023
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/17 SEPTEMBER 2023
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 17 SEPTEMBER AND FORECAST FOR 18 SEPTEMBER - 20 SEPTEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** RED ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 17 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 17 Sep: 145/99
1B. SOLAR FORECAST
18 Sep 19 Sep 20 Sep
Activity R0-R1,chance R2 R0-R1,chance R2 R0-R1,chance R2
Fadeouts Possible Possible Possible
10.7cm/SSN 145/99 140/94 140/94
COMMENT: Solar activity on UT day 17-Sep was at the R0 level.
Solar region AR3435(N10E59, beta) is currently the most significant
region on the solar disk. The far eastern edge of the umbra of
the large trailer spot of this region shows a small area of magnetic
delta configuration, and the southern edge of the trailer spot's
penumbra appears to be growing. A new unnumbered solar region
has emerged on disk at N12W18 consisting of a number of small
spots, and another new region located at N19W58 has also emerged
on disk and has shown growth over the past 24 hours. A new unnumbered
small region has rotated onto the solar disk, currently located
at S26E77. There are currently five numbered solar regions on
the visible disk and 3 unnumbered regions. Other spot groups
are stable or in decay. A small solar filament visible in GONG
H-alpha imagery located at S10W18, slowly lifted off during the
interval 17/0900-1300UT. Solar activity is expected to be at
R0-R1 level over 18-20 Sep, with a slight chance of an R2 flare
from AR3435. No new significantly Earth directed CMEs were observed.
In LASCO C2 imagery a south west CME is visible from 17/1325UT.
This is currently considered to be more associated with prominence
activity on the south west solar limb 17/0900-1000UT in SDO304
imagery, rather than the small filament eruption, but there is
some solar origin ambiguity. An eastward non Earth directed CME
is visible from 17/1636UT. The solar wind speed was variable
on 16-Sep, ranging from 421 to 508 km/s and is currently near
450 km/s. A very weak shock signature is evident in the DSCOVR
solar wind data at 17/0154UT, with the wind speed briefly peaking
at 500km/sec. This shock is attributed to the 14-Sep filament
eruption from the north west solar quadrant. The peak total interplanetary
field strength (IMF, Bt) was 11 nT and the north-south IMF component
(Bz) range was +8 to -9 nT. The solar wind IMF Bz very briefly
fluctuated to -9nT post shock arrival. A strong shock in the
solar wind speed is expected from late in the UT day 18-Sep to
middle of the UT day 19-Sep from a recent large filament eruption.
The ACE EPAM CME precursor channel flux trend suggests CME arrival
may be more towards the second half of this forecast arrival
period. Two small equatorial coronal holes are visible at solar
longitudes E25 and W25.The west located coronal hole is currently
mildly elevating solar wind speeds.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 17 Sep: G0
Estimated Indices 17 Sep : A K
Australian Region 11 33222233
Cocos Island 10 33222232
Darwin 11 43122223
Townsville 11 24222233
Learmonth 11 43222232
Alice Springs 11 43222232
Gingin 12 33222333
Canberra 11 33222233
Hobart 12 33223233
Estimated Antarctic Regional K Indices 17 Sep :
Macquarie Island 16 33344322
Casey 20 54332243
Mawson 27 44333364
Observed Regional daily pc3 Indices 17 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 9 (Quiet)
Canberra 14 (Quiet)
Hobart 19 (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 17 Sep : A
Fredericksburg 14
Planetary 19
Observed AFr/Ap Indices 16 Sep : A K
Fredericksburg 5
Planetary 10 2011 3433
2B. MAGNETIC FORECAST
Date Ap Conditions
18 Sep 12 G0, chance of G1 periods late in UT day.
19 Sep 55 G2, chance of an isolated G3 period.
20 Sep 18 Initially G1 then G0.
COMMENT: ASWFC Geomagnetic Warning 52 was issued on 16 September
and is current for 18-19 Sep. G0 geomagnetic conditions were
observed in the Australian region on 17-Sep. Mostly G0 conditions
were observed in the Antarctic region, with an isolated period
of G1 at Casey. A very weak arrival of the 14-Sep CME was observed
early on 17/0154UT with no significant geomagnetic activity subsequently
observed. A stronger CME associated with a large solar filament
eruption on 16-Sep is expected to increase geomagnetic activity
to G2, with the chance of G3 periods from late 18-Sep to 19-Sep.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
17 Sep Normal Normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
18 Sep Normal Normal-fair Normal-fair
19 Sep Normal Fair-poor Poor
20 Sep Normal Poor-fair Poor-fair
COMMENT: HF radio propagation conditions on UT day 17-Sep were
normal. HF conditions are expected to become moderately to strongly
degraded at middle to high latitudes during 19-20 Sep, due to
the anticipated arrival of a recent CME associated with a large
solar filament eruption on 16-Sep.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
17 Sep 102
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Enhanced by 20% during local night.
Niue Island Region:
Near predicted monthly values.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values during local day.
Enhanced by 15% during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values 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
18 Sep 100 Near predicted monthly values
19 Sep 80 Near predicted monthly values/depressed 15 to
25%
20 Sep 70 Depressed 15 to 25%/near predicted monthly values
COMMENT: ASWFC Preliminary HF Communications Warning 93 was issued
on 17 September and is current for 19-20 Sep. ASWFC SWF HF Communications
Warning 94 was issued on 17 September and is current for 17-19
Sep. Maximum usable frequencies (MUFs) on UT day 17-Sep were
near predicted monthly values. Brief ionospheric phase scintillation
(<1deg.) was observed at Weipa at approximately 17/1000UT. Degraded
HF conditions are expected during 19-20 Sep, particularly for
the southern Australian region, due to expected geomagnetic storm
activity from a recent CME associated with an solar filament
eruption. The timing of any middle latitude ionospheric depression
response will depend on the geomagnetic storm onset time and
subsequent strength. Isolated minor fadeouts possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 16 Sep
Daily Proton Fluence >1 MeV: 4.5E+05
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 6.50E+06 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 1%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.0
DSCOVR Satellite Solar Wind Day Averaged Data for 16 Sep
Speed: 427 km/sec Density: 4.4 p/cc Temp: 105000 K Bz: 0 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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