[Ips-dsgr] ASWFC Daily Report - 19 September 23 issued 2330 UT on 19 Sep 2023 [SEC=OFFICIAL]
Regional Warning Centre
rwc at ips.gov.au
Wed Sep 20 09:30:08 EST 2023
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/19 SEPTEMBER 2023
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
M1.1 0355UT possible lower E. Asia/Aust.
M1.8 0938UT possible lower Mid East/Indian
M4.0 2014UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 19 Sep: 166/120
1B. SOLAR FORECAST
20 Sep 21 Sep 22 Sep
Activity R0-R1, chance R2 R0-R1, chance R2 R0-R1, chance R2
Fadeouts Possible Possible Possible
10.7cm/SSN 162/116 160/114 155/109
COMMENT: Solar activity on UT day 19-Sep was R1, with three R1
solar flares. All flares were from AR3435(N13E43, beta), and
the largest being M4 at 19/2014 UT. There are currently nine
numbered sunspot regions on the solar disk. AR3435 is currently
the most complex, but has not shown much significant growth over
the past 24 hours. AR3437 (S17W30, beta) has shown some minor
growth, and a new unnumbered region has appeared near N08E13.
All other sunspot regions are either stable or in decay. Solar
activity is expected to be R0-R1 with a chance for R2 over 20-22
Sep.
Several weak CMEs were observed on 19-Sep, but none are
considered geoeffective.
A CME impact was observed from 18/1300
UT, whose effects flowed into 19-Sep. There is some uncertainty
of the source of this CME, as it may be from an M2 flare event
on 14-Sep, else it may have been a CME from a large filament
eruption on 16-Sep. Maximum solar wind speeds reached 622 km/s.
On 19-Sep the peak total interplanetary field strength (IMF,
Bt) was 15 nT as CME effects continued from the previous UT day,
and the north-south IMF component (Bz) range was 5 nT to -13
nT. Several periods of sustained southward Bz were observed over
18/2240 - 19/0330 UT and 19/1000 - 19/1600 UT. It is possible
a second CME weakly impacted in the second half of the day, but
since solar wind parameters were already slightly enhanced it
is difficult to discern. A small equatorial coronal hole wind
stream may have also been contributing to enhanced solar wind
speeds. The solar wind speed is expected to remain somewhat enhanced
on 20-Sep but on a declining trend as CME effects subside. Solar
wind speeds may increase again by 22-Sep due to another equatorial
coronal hole wind stream.
Auroras may have been visible at high
latitudes on 19-Sep.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 19 Sep: G1
Estimated Indices 19 Sep : A K
Australian Region 24 44434532
Cocos Island 20 43334442
Darwin 22 44334532
Townsville 24 44434532
Learmonth 29 54435532
Alice Springs 24 44434532
Gingin 27 53434543
Canberra 21 44434432
Hobart 25 44443533
Estimated Antarctic Regional K Indices 19 Sep :
Macquarie Island 47 45566631
Casey 23 54533331
Mawson 71 75645672
Observed Regional daily pc3 Indices 19 Sep :
Darwin 0 (Quiet)
Townsville 2 (Quiet)
Learmonth 6 (Quiet)
Alice Springs 0 (Quiet)
Gingin 40 (Quiet to unsettled)
Canberra 43 (Unsettled)
Hobart 67 (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 19 Sep : A
Fredericksburg 37
Planetary 50
Observed AFr/Ap Indices 18 Sep : A K
Fredericksburg 21
Planetary 41 4322 5764
2B. MAGNETIC FORECAST
Date Ap Conditions
20 Sep 16 G0, chance G1
21 Sep 10 G0
22 Sep 18 G1, slight chance G2
COMMENT: In the Australian region on UT day 19-Sep G1 geomagnetic
conditions were observed. G1-G3 geomagnetic conditions were observed
in the Antarctica region. Planetary conditions reached G3, although
only briefly, around 19/0600 UT. The source of the geomagnetic
activity is somewhat unclear, as there were two possible CME
impacts during the day, one possibly from 14-Sep and one from
16-Sep. As the solar wind parameters were enhanced for most of
the UT day it is difficult to discern a second impact, however
DST-index data suggests a weak impact around 19/1215 UT. G0 geomagnetic
conditions are expected on 20-Sep with a chance for G1 as CME
impacts subside. G0 geomagnetic conditions are expected on 21-Sep,
then G1 geomagnetic conditions may be expected on 22-Sep due
to an equatorial coronal hole. Due to proximity to the September
equinox, there is a small chance for G2 geomagnetic conditions
from this.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
19 Sep Normal-fair Normal Poor
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
20 Sep Normal Normal Fair
21 Sep Normal Normal Normal-fair
22 Sep Normal-fair Normal Fair
COMMENT: HF radio propagation conditions on UT day 19-Sep were
degraded at high latitudes due to recent geomagnetic activity.
Further degradations may be observed in high latitudes, particularly
during local night hours, on 20-Sep before ionospheric conditions
begin to recover. Some further degradations may be observed on
22-Sep due to anticipated geomagnetic activity from a coronal
hole wind stream. H
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
19 Sep 66
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Niue Island Region:
Near predicted monthly values.
Northern Australian Region:
Near predicted monthly values during local day.
Depressed by 20% during local night.
Southern Australian Region:
Depressed by 35% during local day.
Depressed by 15% during local night.
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
20 Sep 80 Depressed 15 to 25%/near predicted monthly values
21 Sep 90 10 to 15% below predicted monthly values
22 Sep 85 Near predicted monthly values
COMMENT: ASWFC HF Communications Warning 95 was issued on 19
September and is current for 19-21 Sep. Maximum usable frequencies
(MUFs) in the Australian region on UT day 19-Sep were near predicted
values to 35% depressed. Spread-F was observed at Hobart and
Canberra, and sporadic-E was observed at Brisbane. Degraded HF
propagation conditions were observed in high latitudes. MUFs
are expected to be 15-25% depressed on 20-Sep before beginning
to recover to near predicted values on 21-Sep. Some further degradations
may be observed late on 22-Sep due to some anticipated geomagnetic
activity from a coronal hole.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 18 Sep
Daily Proton Fluence >1 MeV: 4.2E+07
Daily Proton Fluence >10 MeV: 3.9E+04
Daily Electron Fluence >2 MeV: 7.80E+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 18 Sep
Speed: 437 km/sec Density: 7.8 p/cc Temp: 70800 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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