[Ips-dsgr] ASWFC Daily Report - 24 September 23 issued 2334 UT on 24 Sep 2023 [SEC=OFFICIAL]
rwc
rwc at ips.gov.au
Mon Sep 25 09:34:28 EST 2023
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/24 SEPTEMBER 2023
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 24 SEPTEMBER AND FORECAST FOR 25 SEPTEMBER - 27 SEPTEMBER
STATUS INDICATORS SOL:** RED ** MAG:** RED ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 24 Sep: MR1
Flares Max Fadeout Freq. Sectors
M1.2 0307UT possible lower E. Asia/Aust.
M1.9 0314UT possible lower E. Asia/Aust.
M4.4 0328UT possible lower E. Asia/Aust.
M1.0 1500UT possible lower South American/
Atlantic
Observed 10.7 cm flux/Equivalent Sunspot Number for 24 Sep: 174/128
1B. SOLAR FORECAST
25 Sep 26 Sep 27 Sep
Activity R1-R2, chance R3 R1-R2, chance R3 R1-R2, chance R3
Fadeouts Probable Probable Probable
10.7cm/SSN 172/126 168/122 164/118
COMMENT: Solar activity on UT day 24-Sep was at the R1 level,
due to a multi-peaked M4.4 flare at 24/0328UT and an M1.0 flare
at 25/1500UT, there were also multiple strong C-class flares
over the day. There are currently ten numbered sunspot regions
visible on the solar disk and one unnumbered region. AR3435 (N10W23,
beta-delta) and AR3445 (S13E10, gamma-delta) are the most magnetically
complex regions on the solar disk. AR3445 was responsible for
the largest flare of the UT day and for the majority of the strong
C-class flares. Both of these regions showed spot development
over the UT day, with AR3435 developing a small delta spot in
the north and AR3445 exhibited complex spot movement coupled
with the emergence of new spots. The M1.0 flare was produced
by AR3443 (N28W66, beta) which exhibited decay in its intermediate
spots. All other numbered regions were either stable or in decay.
An unnumbered region has appeared on the solar disk at around
S23E23 with gamma magnetic complexity, but this region is small.
Solar activity over 25-27 Sep is expected to be R1-R2, with a
slight chance of R3. The > 10MeV proton flux was enhanced over
24-Sep. S0 conditions, with the chance of S1 are expected on
25-Sep dependent on flaring activity. Multiple CMEs were observed
on 24-Sep, currently none are considered significantly geoeffective.
A northwest directed CME is visible in SOHO and STEREO-A imagery
from 24/0748UT, this event is associated with an eruption on
the limb is visible in SDO and GOES SUVI imagery from 24/0719UT
at around N25. Modelling suggests this CME is not geoeffective.
A northwest directed CME is visible in SOHO and STEREO-A imagery
from 24/1012UT, this event is associated with coronal movement
visible behind the western limb visible in GOES SUVI imagery.
Modelling suggests this CME is not geoeffective. A narrow, west
directed CME is visible in SOHO imagery from 24/1536UT, corresponding
with a Type II radio sweep. No on disk activity is visible associated
with this CME. this CME is currently considered geoeffective,
further analysis will be performed when more imagery is available.
A faint, west directed CME is visible in SOHO and STEREO-A imagery
from 24/1836UT, possibly associated with an eruption on the western
limb in SDO and GOES SUVI imagery at around N20 from 24/1559UT.
Modelling suggests the possibility of a faint glancing impact
with Earth on 29-Sep at 1800UT +/- 12 hours. A strong shock in
the solar wind speed was detected at 24/1954UT. Prior to this
an energetic ion enhancement was detected by ACE EPAM beginning
at 24/1400UT. This indicates a CME impact has occurred. The solar
wind speed on UT day 24-Sep was steady for most of the day until
the shock at 24/1954UT. The wind speed jumped from around 300
km/s to 460 km/s and is currently at around 440 km/s. The peak
total interplanetary field strength (IMF, Bt) was 28 nT and the
north-south IMF component range was +21 to -28 nT. A sustained
period of mostly -Bz began at around 24/1954UT and ended at 24/2251UT.
The solar wind speed is expected to remain elevated over 25-26
Sep due to a recent CME impact. Further enhancements may occur
on 25-Sep due to possible further 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 24 Sep: G1
Estimated Indices 24 Sep : A K
Australian Region 11 11220054
Cocos Island 11 21210054
Darwin 11 11120054
Townsville 15 21220055
Learmonth 11 21210054
Alice Springs 11 11120054
Gingin 11 20120054
Canberra 7 01220034
Hobart 11 01230035
Estimated Antarctic Regional K Indices 24 Sep :
Macquarie Island 11 01331044
Casey 13 22221045
Mawson 38 43422267
Observed Regional daily pc3 Indices 24 Sep :
Darwin 2 (Quiet)
Townsville 5 (Quiet)
Learmonth 4 (Quiet)
Alice Springs 4 (Quiet)
Gingin 9 (Quiet)
Canberra 27 (Quiet to unsettled)
Hobart 35 (Quiet to unsettled)
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 24 Sep : A
Fredericksburg 11
Planetary 20
Observed AFr/Ap Indices 23 Sep : A K
Fredericksburg 9
Planetary 13 3223 3332
2B. MAGNETIC FORECAST
Date Ap Conditions
25 Sep 28 G1 - G2, chance of G3
26 Sep 12 G0, chance of G1
27 Sep 8 G0
COMMENT: ASWFC Geomagnetic Warning 58 was issued on 24 September
and is current for 25-27 Sep. G1 geomagnetic conditions were
observed in the Australian region on UT day 24-Sep. Mostly G0
geomagnetic conditions were observed in the Antarctic region,
with an isolated period of G1 at Casey and periods of G2-G3 at
Mawson. G2 geomagnetic conditions were observed globally. G1-G2
geomagnetic conditions, with a chance of G3 are expected on 25-Sep
and G0 conditions with a chance of G1 are expected on 26-Sep.
Due to a recent CME impact and the chance 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
24 Sep Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
25 Sep Fair Fair Fair-poor
26 Sep Normal Normal Normal-fair
27 Sep Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 24-Sep were
mostly normal. Mildly degraded HF propagation conditions are
expected on 25-Sep, particularly at higher latitudes, due to
recent and ongoing geomagnetic activity. Degraded conditions
may continue into 26-Sep dependent on how long the geomagnetic
activity persists. Otherwise mostly normal HF propagation conditions
are expected over 26-27 Sep. Shortwave fadeouts are probable.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
24 Sep 113
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 15% during local day.
Enhanced by 40% during local night.
Niue Island Region:
Enhanced by 20% during local day.
Enhanced by 50% during local night.
Enhanced by 20% after local dawn.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 15% 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
25 Sep 100 Near predicted monthly values/depressed 10 to
15%
26 Sep 115 Near to 15% above predicted monthly values
27 Sep 115 Near to 15% above predicted monthly values
COMMENT: ASWFC Preliminary HF Communications Warning 99 was issued
on 23 September and is current for 24-26 Sep. ASWFC SWF HF Communications
Warning 100 was issued on 24 September and is current for 25-27
Sep. Maximum usable frequencies (MUFs) in the Australian region
on UT day 24-Sep were near predicted values in the Australian
region. Spread-F was observed at Hobart during local night hours.
Depressions are expected on 25-Sep, particularly in the southern
Australian region, due to recent and ongoing geomagnetic activity.
Depressions may continue into 26-Sep dependent on how long the
geomagnetic activity persists. Otherwise MUFs are expected to
be near monthly predicted values to 15% enhanced over 26-27 Sep.
Shortwave fadeouts are probable.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 23 Sep
Daily Proton Fluence >1 MeV: 1.1E+05
Daily Proton Fluence >10 MeV: 1.9E+04
Daily Electron Fluence >2 MeV: 7.60E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 9%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.2
DSCOVR Satellite Solar Wind Day Averaged Data for 23 Sep
Speed: 348 km/sec Density: 0.4 p/cc Temp: 38500 K Bz: -3 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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