[Ips-dsgr] ASWFC Daily Report - 17 April 24 issued 2330 UT on 17 Apr 2024 [SEC=OFFICIAL]
Regional Warning Centre
rwc at ips.gov.au
Thu Apr 18 09:30:59 EST 2024
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/17 APRIL 2024
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 17 APRIL AND FORECAST FOR 18 APRIL - 20 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 17 Apr: R1
Flares Max Fadeout Freq. Sectors
M1.6 2208UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 17 Apr: 217/167
1B. SOLAR FORECAST
18 Apr 19 Apr 20 Apr
Activity R0-R1, chance R2 R0-R1, chance R2 R0-R1, chance R2
Fadeouts Possible Possible Possible
10.7cm/SSN 210/161 200/152 190/143
COMMENT:
Solar activity on UT day 17-Apr was at the R1 level, due to an M1.6 flare
at 17/2208UT produced by AR3645 (S09E24, beta-gamma). Several high C-class
flares were also observed.
There are currently thirteen numbered sunspot regions on the solar disk.
AR3633 (S10W78, beta), AR3635 (N19W47, alpha), AR3637 (S10E12, beta), AR3638
S16E19, beta-gamma), AR3643 (S12E32, beta), AR3645 and AR3646 (N21E64, beta)
all showed spot development on 17-Apr. Of these, AR3643 and AR3645 showed the
most significant development. Active regions AR3637, AR3638, AR3643 and AR3645
are all developing in close proximity to each other and were collectively
responsible for the large C-class flares along with AR3639 (N29E29, beta).
These five regions make up the most significant active regions on the solar
disk. Meanwhile AR3634 (N25W72, beta) is the largest active region, but is
magnetically simple, stable and soon to rotate off the solar disk. All other
numbered regions are either stable or in decay.
Solar activity is expected to be at R0-R1 levels over 18-20 Apr, with a
chance of R2.
Solar radiation conditions were at the S0 level on 17-Apr and are expected
to remain at this level over 18-20 Apr.
No significantly geoeffective CMEs were observed on 17-Apr. A large solar
filament lift off was observed from 17/0215UT at around N30W05. This lift off
is associated with a north directed CME from 17/0236UT visible in SOHO and
STEREO-A imagery. Modelling suggests a chance of a glancing impact on 20-Apr at
1500UT +/- 12 hours. Although this is lower confidence due to a lack of
available
STEREO-A imagery. This impact is not expected to be significant. Several other
narrow CMEs were observed but none are considered geoeffective.
The solar wind speed was mildly elevated and steady over the UT day 17-Apr
ranging from 334 to 402 km/s. The wind speed is currently around 390 km/s.
The peak total interplanetary field strength (IMF, Bt) was 10 nT and the
north-south IMF component (Bz) range was +9 to -8 nT.
There is a chance of an increase in solar wind speed in the first half of 18-Apr
due to the late arrival of a possible glancing impact from a CME first observed
from 15-Apr. Otherwise, the solar wind is expected to remain steady and slightly
elevated over 18-19 Apr, a further increase is possible on 20-Apr due to a
possible glancing impact from a CME first observe on 17-Apr.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 17 Apr: G0
Estimated Indices 17 Apr : A K
Australian Region 4 21120212
Cocos Island 3 21120101
Darwin 5 22220212
Townsville 5 22220212
Learmonth 5 22121212
Alice Springs 4 22120211
Gingin 4 21121211
Canberra 4 21120212
Kennaook Cape Grim 6 21121312
Hobart 6 21121312
Estimated Antarctic Regional K Indices 17 Apr :
Macquarie Island 8 20133410
Casey 9 33321222
Mawson 9 32222322
Observed Regional daily pc3 Indices 17 Apr :
Darwin 6 (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 17 Apr : A
Fredericksburg 8
Planetary 9
Observed AFr/Ap Indices 16 Apr : A K
Fredericksburg 17
Planetary 30 4344 4454
2B. MAGNETIC FORECAST
Date Ap Conditions
18 Apr 13 G0, chance of G1
19 Apr 8 G0
20 Apr 15 G0, chance of G1
COMMENT:
G0 geomagnetic conditions were observed in the Australian and Antarctic
regions on UT day 17-Apr.
G0 geomagnetic conditions, with a chance of G1 are expected on 18-Apr,
due to a combination of ongoing CME effects and a possible glancing impact
from a CME first observed on 15-Apr. G0 conditions are expected on 19-20
Apr, with a further chance of G1 on 20-Apr due to a possible glancing
impact from a CME first observed on 17-Apr.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
17 Apr Normal-fair Normal-fair Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
18 Apr Normal Normal Normal-fair
19 Apr Normal Normal Normal-fair
20 Apr Normal Normal Normal-fair
COMMENT:
HF radio propagation conditions on UT day 17-Apr were degraded at middle
to high latitudes in the northern hemisphere for the first third of the
day, before recovering to mostly normal conditions for the remainder of
the day.
HF radio propagation conditions are expected to be mostly normal over
18-20 Apr, with mildly degraded conditions again possible for middle to
high latitudes on 18-Apr. Shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
17 Apr 127
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Enhanced by 30% during local night.
Enhanced by 20% after local dawn.
Niue Island Region:
Near predicted monthly values during local day.
Enhanced by 25% during local night.
Northern Australian Region:
Mostly near predicted monthly values.
Enhanced by 20% after local dawn.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 20% 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
18 Apr 130 Near to 15% above predicted monthly values
19 Apr 130 Near to 15% above predicted monthly values
20 Apr 130 Near to 15% above predicted monthly values
COMMENT:
Maximum usable frequencies (MUFs) in the Australian region on UT day
18-Apr were near predicted monthly values, with enhanced conditions
observed in the northern Australian region after local dawn. Long
periods of spread F were observed at Hobart, Canberra and Perth during
local night.
MUFs are expected to be near predicted monthly values to 15% enhanced
over 18-20 Apr. Shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 16 Apr
Daily Proton Fluence >1 MeV: 3.8E+06
Daily Proton Fluence >10 MeV: 1.5E+04
Daily Electron Fluence >2 MeV: 9.40E+05 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 1%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.6
DSCOVR Satellite Solar Wind Day Averaged Data for 16 Apr
Speed: 373 km/sec Density: 11.5 p/cc Temp: 39800 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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