[Ips-dsgr] ASWFC Daily Report - 18 December 23 issued 2330 UT on 18 Dec 2023 [SEC=OFFICIAL]
Regional Warning Centre
rwc at ips.gov.au
Tue Dec 19 10:30:11 EST 2023
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 DECEMBER 2023
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 DECEMBER AND FORECAST FOR 19 DECEMBER - 21 DECEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: ** RED **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 Dec: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Dec: 161/115
1B. SOLAR FORECAST
19 Dec 20 Dec 21 Dec
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 162/116 162/116 164/118
COMMENT: Solar activity on UT day 18-Dec was at the R0 level.
Solar region AR3519(S10W27, beta) is currently the largest region
on disk and continues to show decline in its trailer spots. Solar
regions AR3528(N09E15, beta) and AR3529(S20E55, beta) have shown
growth. There are currently nine numbered sunspot regions visible
on the solar disk. All other sunspot regions are small and mostly
stable. Solar activity is expected to be at R0-R1 levels over
19-21 Dec. A small four degree long solar filament located at
S08W29 erupted in GONG H-alpha imagery during the interval 18/0653-0749UT.
A westward CME was observed in LASCO C2 from 18/1100UT which
is not considered associated with the small filament eruption.
A solar filament in the south east solar quadrant centred at
S20E40 has been unstable. A long filament in the north east solar
quadrant has remained stable. The solar wind speed on UT day
18-Dec was mostly elevated with an increase toward the end of
the UT day, ranging from 428 to 590 km/s and is currently near
590 km/s. The peak total interplanetary field strength (IMF,
Bt) was 13 nT and the north south IMF component (Bz) range was
+12 to -11 nT. The IMF Bz component periodically fluctuated southward
throughout the UT day. The solar wind speed is expected to remain
elevated over 19-20 Dec due to coronal hole high speed wind stream
effects from a moderate sized coronal hole in the north west
solar quadrant currently centred at N20W40. Another isolated
coronal hole is starting to cross the solar central meridian
in the southern solar hemisphere centred at S25E10 and may moderately
increase solar wind speeds 24-25 Dec. Old solar region AR3500
which produced an R2 flare on its previous disk transit is due
to return to the south east solar limb (S18) around 18-Dec.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Dec: G0
Estimated Indices 18 Dec : A K
Australian Region 25 34553234
Cocos Island 16 34442223
Darwin 25 34553234
Townsville 34 35653344
Learmonth 31 35653324
Alice Springs 27 35553234
Gingin 26 34553334
Canberra 26 34643234
Hobart 25 24643234
Estimated Antarctic Regional K Indices 18 Dec :
Macquarie Island 30 34654333
Casey 41 56643335
Mawson 51 35754446
Observed Regional daily pc3 Indices 18 Dec :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 12 (Quiet)
Canberra 6 (Quiet)
Hobart 20 (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 18 Dec : A
Fredericksburg 17
Planetary 27
Observed AFr/Ap Indices 17 Dec : A K
Fredericksburg 32
Planetary 44 3445 6723
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Dec 16 G0, slight chance of G1 period
20 Dec 10 G0
21 Dec 10 G0
COMMENT: G1 geomagnetic conditions were observed in the Australian
region on UT day 18-Dec following declining influences from a
CME arrival combined with coronal hole wind stream influences.
An isolated G2 period was observed at some locations. The planetary
Kp reached G2 for one K index period following an interval of
southward IMF conditions. G1-G2 geomagnetic conditions were observed
in the Antarctic region, with an isolated period of G3 observed
at Mawson. G0 geomagnetic conditions are expected over 19-21
Dec, with a slight chance of a G1 period on 19-Dec.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Dec Normal Fair-normal Fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Dec Normal Fair-normal Fair
20 Dec Normal Normal Normal-fair
21 Dec Normal Normal Normal-fair
COMMENT: HF radio communication conditions on UT day 18-Dec were
fair at middle to high latitudes. Fair conditions are expected
for 19-Dec, then improving with normal conditions expected over
20-21 Dec. Isolated shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Dec 71
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 15-20%.
Niue Island Region:
Enhanced by 20% during local day.
Enhanced by 55% during local night.
Northern Australian Region:
Depressed by 15% during local day.
Near predicted monthly values during local night.
Depressed by 20% after local dawn.
Southern Australian Region:
Depressed by 30% during local day.
Depressed by 20% during local night and after local dawn.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Nov 114
Dec 100
Jan 98
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
19 Dec 50 Depressed 15 to 20%/near predicted monthly values
20 Dec 100 Near predicted monthly values
21 Dec 100 Near predicted monthly values
COMMENT: ASWFC HF Communications Warning 131 was issued on 18
December and is current for 19 Dec only. Maximum usable frequencies
(MUFs) were generally depressed 15-30% during the local day in
the Australian region on UT day 18-Dec. Depressions of 20% have
been observed after local dawn this morning due to recent geomagnetic
activity. MUFs are generally expected to be 15-20% depressed
for 19-Dec, then near predicted monthly values for 20-21 Dec.
Isolated shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Dec
Daily Proton Fluence >1 MeV: 8.3E+06
Daily Proton Fluence >10 MeV: 3.7E+04
Daily Electron Fluence >2 MeV: 1.30E+06 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 1%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.3
DSCOVR Satellite Solar Wind Day Averaged Data for 17 Dec
Speed: 480 km/sec Density: 19.1 p/cc Temp: 178000 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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