[Ips-dsgr] ASWFC Daily Report - 18 September 23 issued 2330 UT on 18 Sep 2023 [SEC=OFFICIAL]
Regional Warning Centre
rwc at ips.gov.au
Tue Sep 19 09:30:49 EST 2023
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 SEPTEMBER 2023
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 SEPTEMBER AND FORECAST FOR 19 SEPTEMBER - 21 SEPTEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 Sep: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Sep: 155/109
1B. SOLAR FORECAST
19 Sep 20 Sep 21 Sep
Activity R0-R1, chance R2 R0-R1, chance R2 R0-R1, chance R2
Fadeouts Possible Possible Possible
10.7cm/SSN 154/109 154/109 152/107
COMMENT: Solar activity on UT day 18-Sep was R0, with no significant
solar flares. There are currently eight numbered sunspot regions
on the solar disk. AR3436 (N21W33, gamma) has shown some minor
growth and AR3437 (S17W16, beta-gamma) has shown rapid growth
over the past 24 hours. All other sunspot regions are either
stable or in decay. Solar activity is expected to be R0-R1 with
a chance fro R2 over 19-21 Sep.
A partial halo CME was observed from 18/1248 UT in the northwest,
but it cannot be correlated to any on-disk activity and is therefore
considered farside and not geoeffective. A prominence eruption
was observed from 18/1800 UT on the southwest solar limb but
no indicators of a CME have been observed yet. No other CMEs were observed.
A shock to the solar wind was observed from 18/1300 UT, likely
the arrival of a CME first observed on 16-Sep. At this time
the solar wind speed increased from near 420 km/s to near 550 km/s,
reaching a maximum of 598 km/s, but appears to have begun declining.
The peak total interplanetary field strength (IMF, Bt) reached 23 nT.
The north-south IMF component (Bz) range was -17 nT to +14 nT,
with periods of sustained southward Bz between 18/1550-1900 UT.
The solar wind speed may decline on 19-Sep but still remain elevated
due to a small coronal hole. The solar wind speed may reach background
levels by 21-Sep.
At 18/0420 UT the 10 MeV proton flux increased
to 1.98 pfu but has since returned to near background levels
and S0 solar radiation storm conditions are expected.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Sep: G0
Estimated Indices 18 Sep : A K
Australian Region 16 32224443
Cocos Island 12 32214332
Darwin 13 32214333
Townsville 19 33224444
Learmonth 25 33225553
Alice Springs 16 32214443
Gingin 24 42214554
Canberra 15 22224443
Hobart 20 22224553
Estimated Antarctic Regional K Indices 18 Sep :
Macquarie Island 33 23544653
Casey 25 43435434
Mawson 48 66524653
Observed Regional daily pc3 Indices 18 Sep :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 2 (Quiet)
Canberra 2 (Quiet)
Hobart 24 (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 18 Sep : A
Fredericksburg 23
Planetary 29
Observed AFr/Ap Indices 17 Sep : A K
Fredericksburg 14
Planetary 20 4333 3443
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Sep 18 G0, chance G1
20 Sep 12 G0
21 Sep 8 G0
COMMENT: ASWFC Geomagnetic Warning 52 was issued on 16 September
and is current for 18-19 Sep. On UT day 18-Sep in the Australia
region, G1 geomagnetic conditions were observed in Learmonth,
Gingin and Hobart, but otherwise was G0. The Antarctica region
observed G1-G2 geomagnetic conditions. Overall planetary geomagnetic
conditions reached G1. The source of the geomagnetic activity
was the anticipated arrival of a CME that was first observed
on 16-Sep. Geomagnetic activity commenced from 18/1300 UT but
has since subsided. Mostly G0 geomagnetic conditions are expected
over 19-21 Sep, with a small chance for an isolated period of
G1 at the beginning of 19-Sep.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Sep Normal-fair Fair Fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Sep Normal-fair Fair Fair-poor
20 Sep Normal Normal-fair Fair
21 Sep Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 18-Sep were
degraded at high and middle latitudes, particularly late in the
UT day, due to geomagnetic activity that commenced from 18/1300
UT. Due to this geomagnetic activity, HF radio conditions are
expected to continue to be moderately degraded over 19-20 Sep
in high and middle latitudes. HF conditions are expected to recover
by 21-Sep.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Sep 102
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Niue Island Region:
Depressed by 15% during local day.
Near predicted monthly values during local night.
Northern Australian Region:
Mostly near predicted monthly values.
Southern Australian Region:
Mostly near predicted monthly values.
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
19 Sep 90 Near predicted monthly values/depressed 15 to
25%
20 Sep 80 Depressed 15 to 25%/near predicted monthly values
21 Sep 90 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 18-Sep were
mostly near predicted values in the Australian region. Sporadic-E
was observed at Norfolk Island and in Brisbane during local night/
dawn hours. Spread F was observed in Hobart and Perth during
local night hours. MUF depressions of 15-25% are expected over
19-21 Sep due to geomagnetic activity that was observed late
in UT day 18-Sep. Degraded conditions are likely at high and
middle latitudes during local night hours.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Sep
Daily Proton Fluence >1 MeV: 1.5E+07
Daily Proton Fluence >10 MeV: 2.3E+04
Daily Electron Fluence >2 MeV: 2.50E+06 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 1%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B9.2
DSCOVR Satellite Solar Wind Day Averaged Data for 17 Sep
Speed: 459 km/sec Density: 9.4 p/cc Temp: 165000 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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