[Ips-dsgr] ASWFC Daily Report - 18 April 24 issued 2330 UT on 18 Apr 2024 [SEC=OFFICIAL]
Regional Warning Centre
rwc at ips.gov.au
Fri Apr 19 09:30:55 EST 2024
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 APRIL 2024
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 APRIL AND FORECAST FOR 19 APRIL - 21 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 Apr: R1
Flares Max Fadeout Freq. Sectors
M1.6 17/2208UT possible lower East Pacific/
North American
M2.2 0248UT possible lower E. Asia/Aust.
M1.3 0739UT possible lower Mid East/Indian
M1.6 2001UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Apr: 227/177
1B. SOLAR FORECAST
19 Apr 20 Apr 21 Apr
Activity R1, chance of R2 R1, chance of R2 R1, chance of R2
Fadeouts Possible Possible Possible
10.7cm/SSN 225/175 220/170 220/170
COMMENT: Solar activity on UT day 18-Apr was at the R1 level,
due to an M2.2 flare at 18/0253UT, an M1.3 flare at 18/0809UT
and an M1.6 flare which peaked at 18/2001UT and 18/2016UT. There
are currently thirteen numbered sunspot regions on the solar
disk and one unnumbered region. The collection of sunspot regions
consisting of AR3643 (S12E23, beta), AR3645 (S09E10, beta-delta)
and newly numbered AR3647 (S15E15, beta-delta) along with the
nearby AR3638 (S16E07, beta) were responsible for all the M-class
flares over the UT day and are the most significant regions on
the solar disk. They all showed spot development on 18-Apr, with
at least two delta spot candidates visible. AR3635 (N19W60, beta),
AR3636 (S21W22, alpha) and AR3639 (N29E17, beta) also showed
spot development but are magnetically simple regions with no
history of flaring. All other numbered regions are either stable
or in decay. An unnumbered region has developed on the solar
disk at around N15W08 with beta magnetic characteristics. Solar
activity is expected to be at the R1 level over 19-21 Apr, with
a chance of R2. Primarily due to the combination of AR3643, AR3645
and AR3647. Solar radiation conditions were at the S0 level on
18-Apr and are expected to remain at this level over 19-21 Apr.
No geoeffective CMEs were observed on 18-Apr. STEREO-A images
were unavailable for CME modelling over 18-Apr, making CME analysis
less certain today. A series of slow southeast directed CMEs
were observed from 18/0336UT through to 18/1800UT in SOHO and
STEREO-A imagery. These are likely due to eruptions associated
with flares produced by the conglomerate of sunspot groups mentioned
previously. These CMEs are not considered geoeffective. A west
directed CME is visible in SOHO and STEREO-A imagery from 18/1800UT
with associated faint coronal movement visible behind the western
limb in GOES SUVI from 18/1528UT. This CME is not considered
geoeffective. The solar wind speed was mostly in decline on UT
day 18-Apr, with an increase observed from 18/2030UT onwards.
The wind speed ranged from 300 to 440 km/s and is currently around
350 km/s. The peak total interplanetary field strength (IMF,
Bt) was 8 nT and the north-south IMF component (Bz) range was
+8 to -4 nT. A sudden small increase in wind speed and IMF Bt
at around 18/2030UT suggests the possible late arrival of the
anticipated glancing impact from a CME first observed on 15-Apr.
The solar wind speed is expected to remain around current levels
until a possible increase on 20-Apr due to a possible glancing
impact from a CME first observed on 16-Apr. The solar wind is
expected to be slightly enhanced on 21-Apr due to high speed
wind stream effects from a small coronal hole rotating towards
a geoeffective location.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Apr: Quiet
Estimated Indices 18 Apr : A K
Australian Region 2 21100001
Cocos Island 1 21100000
Darwin 3 22100002
Townsville 3 22100012
Learmonth 2 21100001
Alice Springs 2 21100002
Gingin 2 21100001
Canberra 1 11000001
Kennaook Cape Grim 1 11100001
Hobart 1 11100001
Estimated Antarctic Regional K Indices 18 Apr :
Macquarie Island 0 00000001
Casey 4 32210001
Mawson 2 22200000
Observed Regional daily pc3 Indices 18 Apr :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 0 (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 Apr : A
Fredericksburg 5
Planetary 6
Observed AFr/Ap Indices 17 Apr : A K
Fredericksburg 8
Planetary 7 3102 2212
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Apr 7 G0
20 Apr 15 G0, chance of G1
21 Apr 10 G0
COMMENT: G0 geomagnetic conditions were observed in the Australian
and Antarctic regions on UT day 18-Apr. G0 geomagnetic conditions
are expected over 19-21 Apr, with a chance of G1 on 20-Apr due
to a possible glancing impact from a CME first observed on 16-Apr.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Apr Normal Normal Normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Apr Normal Normal Normal
20 Apr Normal Normal Normal-fair
21 Apr Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 18-Apr were
mostly normal. HF radio propagation conditions are expected to
be mostly normal over 19-21 Apr, with a chance of mild degradations
at high latitudes over 20-21 Apr due to possible geomagnetic
activity on 20-Apr. Shortwave fadeouts are probable.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Apr 133
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Enhanced by 85% during local night.
Niue Island Region:
Near predicted monthly values during local day.
Enhanced by 35% during local night.
Northern Australian Region:
Near predicted monthly values during local day.
Enhanced by 35% during local night.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Mar 120
Apr 114
May 115
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
19 Apr 135 Near to 15% above predicted monthly values
20 Apr 135 Near to 15% above predicted monthly values
21 Apr 135 Near to 15% above predicted monthly values
COMMENT: ASWFC SWF HF Communications Warning 37 was issued on
18 April and is current for 18-20 Apr. Maximum usable frequencies
(MUFs) in the Australian region on UT day 18-Apr were near predicted
monthly values, with enhanced conditions observed at Darwin during
local night. Long periods of spread F were observed at Canberra
during local night. MUFs are expected to be near predicted monthly
values to 15% enhanced over 19-21 Apr, with a chance of mild
depressions in the southern Australian region over 20-21 Apr
due to possible geomagnetic activity on 20-Apr. Shortwave fadeouts
are probable.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Apr
Daily Proton Fluence >1 MeV: 9.0E+05
Daily Proton Fluence >10 MeV: 1.5E+04
Daily Electron Fluence >2 MeV: 9.10E+05 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 1%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.9
DSCOVR Satellite Solar Wind Day Averaged Data for 17 Apr
Speed: 365 km/sec Density: 5.5 p/cc Temp: 56600 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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