[Ips-dsgr] ASWFC Daily Report - 21 April 23 issued 2331 UT on 21 Apr 2023 [SEC=OFFICIAL]
Regional Warning Centre
rwc at ips.gov.au
Sat Apr 22 09:31:14 EST 2023
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/21 APRIL 2023
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 21 APRIL AND FORECAST FOR 22 APRIL - 24 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:** RED ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 21 Apr: R1
Flares Max Fadeout Freq. Sectors
M1.7 1813UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 21 Apr: 151/106
1B. SOLAR FORECAST
22 Apr 23 Apr 24 Apr
Activity R0-R1 R0-R1 R0-R1
Fadeouts Possible Possible Possible
10.7cm/SSN 140/94 135/89 130/84
COMMENT: Solar activity on UT day 21-Apr was at the R1 level,
due to a long duration M1.7 flare from AR3283 (S19W09, beta)
at 21/1815UT. There are currently six numbered sunspot regions
visible on the solar disk. AR3282 (N11W37, beta) is the largest
sunspot region and has shown spot development in its leader spot
whilst its intermediate spots have decayed. AR3283 has decayed
since producing the R1 flare event. Newly numbered AR3285 (S19E71,
beta) recently rotated over the eastern limb and appears stable.
AR3275 (N19W83, alpha) will soon rotate over the western limb
and appears stable. All other sunspot regions are either stable
or in decay. Solar activity is expected to be at R0-R1 levels
over 22-24 Apr. A filament eruption was observed, visible in
H-alpha imagery at 21/1801UT from S19W07. This eruption is associated
with the aforementioned M1.7 flare from AR3283. A subsequent
full halo CME was observed in LASCO C2 and STEREO-A coronagraph
imagery at 21/1812UT. Modelling indicates this CME is Earth-directed,
with an impact to Earth's magnetosphere expected in the second
half of UT day 23-Apr. No other Earth-directed CMEs have been
observed. The solar wind speed on UT day 21-Apr was mostly stable,
ranging from 360 to 410 km/s. The peak total interplanetary magnetic
field strength (IMF, Bt) was 7 nT and the north-south IMF component
(Bz) range was +5 to -6 nT. A period of sustained southward IMF
conditions was observed starting at 21/1315UT and is ongoing.
A large coronal hole in the southern solar hemisphere may increase
solar wind speeds over 23-24 Apr, but its influence may be limited
due to its southern extent.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 21 Apr: G0
Estimated Indices 21 Apr : A K
Australian Region 6 22130222
Cocos Island 6 22110232
Darwin 7 32121222
Townsville 8 32131222
Learmonth 10 32121333
Alice Springs 6 21130222
Gingin 8 21030333
Canberra 5 21030222
Hobart 7 21140222
Estimated Antarctic Regional K Indices 21 Apr :
Macquarie Island 11 11151322
Casey 12 33321333
Mawson 34 32222367
Observed Regional daily pc3 Indices 21 Apr :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 0 (Quiet)
Hobart 2 (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 21 Apr : A
Fredericksburg 9
Planetary 10
Observed AFr/Ap Indices 20 Apr : A K
Fredericksburg 5
Planetary 4 1011 1212
2B. MAGNETIC FORECAST
Date Ap Conditions
22 Apr 10 G0
23 Apr 60 G2-G3
24 Apr 30 G1, chance G2
COMMENT: G0 geomagnetic conditions were observed in the Australian
region on UT day 21-Apr. Mostly G0-G1 geomagnetic conditions
were observed in the Antarctic region, with an isolated period
of G2-G3 observed at Mawson. G0 geomagnetic conditions are expected
on 22-Apr. G2-G3 geomagnetic conditions are expected on 23-Apr
due to the expected arrival of a CME first observed on 21-Apr.
G1 geomagnetic conditions are expected on 24-Apr, with a chance
of G2 as CME impacts abate.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
21 Apr Normal Normal Normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
22 Apr Normal Normal Normal-fair
23 Apr Poor Poor Poor
24 Apr Fair Fair Fair-poor
COMMENT: Mostly normal HF propagation conditions were observed
on 21-Apr, with some degradations observed during local night
hours. Mostly normal HF propagation conditions are expected on
22-Apr. Fair to poor HF conditions are expected over 23-24 Apr
due to a CME impact from a CME first observed on 21-Apr.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
21 Apr 114
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 20% during local day.
Enhanced by 45% during local night.
Niue Island Region:
Enhanced by 30% during local day.
Enhanced by 45% during local night.
Northern Australian Region:
Enhanced by 15% during local day.
Near predicted monthly values during local night.
Southern Australian Region:
Enhanced by 15% during local day.
Enhanced by 20% during local night.
Antarctic Region (Casey/Scott Base/Davis/Mawson):
Enhanced by 30% over the UT day.
Monthly T index:
Month T index
Mar 132
Apr 84
May 84
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
22 Apr 115 Near to 15% above predicted monthly values
23 Apr 95 Near predicted monthly values
24 Apr 60 Depressed 15%/near predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) on UT day 21-Apr in
the Australian region were enhanced by 15-20%. Sporadic-E was
observed at Brisbane. Spread F was observed at Hobart during
local night hours. MUFs are expected to be 15-25% enhanced on
22-Apr. MUFs are expected to be near predicted monthly values
on 23-Apr and depressed by 15% on 24-Apr due to a CME impact
on 23-Apr.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 20 Apr
Daily Proton Fluence >1 MeV: 6.8E+04
Daily Proton Fluence >10 MeV: 2.2E+04
Daily Electron Fluence >2 MeV: 1.40E+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 20 Apr
Speed: 400 km/sec Density: 5.5 p/cc Temp: 16600 K Bz: 7 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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