[Ips-dsgr] SWS Daily Report - 20 April 21 issued 2330 UT on 20 Apr 2021
Regional Warning Centre
rwc at ips.gov.au
Wed Apr 21 09:30:07 EST 2021
SUBJ: SWS DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/20 APRIL 2021 BY Space Weather Services
FROM THE AUSTRALIAN SPACE FORECAST CENTRE
SUMMARY FOR 20 APRIL AND FORECAST FOR 21 APRIL - 23 APRIL
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
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1A. SOLAR SUMMARY
Activity 20 Apr: Moderate
Flares Max Fadeout Freq. Sectors
M1/-- 19/2342UT possible lower West Pacific
Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Apr: 80/20
1B. SOLAR FORECAST
21 Apr 22 Apr 23 Apr
Activity Low Low Low
Fadeouts Possible Possible Possible
10.7cm/SSN 84/26 82/23 82/23
COMMENT: Solar activity was low on UT day 20 April. There are
currently four numbered regions on the visible disk, AR2815,
AR2816, AR2817 and AR2818. There were a series of B-class flares
from regions 2816 and 2817 and one C1.9 flare at 1215UT from
region 2814 that has just rotated off the Eastern limb of the
Sun. Also region 2816 produced a M1.1 flare at the end of UT
day 19 April at 2342 UT that caused a Short Wave Fadeout. A narrow
Eastward CME associated with this flare does not seem to have
a geoeffective component. No other earthward directed CMEs were
observed. Solar activity is expected to be low for the next three
UT days, 21-23 April with a slight possibility of isolated M-class
event. On UT day 20 April, the solar wind speed varied mostly
between 565 km/s and 670 km/s due to the effects of the Southern
polar coronal hole with extension into the low latitudes. The
IMF (Bt) peaked at 7 nT and the north-south IMF (Bz) range was
+4/-5 nT. The solar wind speed is expected to gradually decrease
on UT days 21-22 April due to waning coronal hole effects. However
another equatorial coronal hole will move into geoeffective position
late on UT day 22 or early on 23 April, elevating the solar wind
speed to moderately enhanced levels.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 20 Apr: Quiet to Active
Estimated Indices 20 Apr : A K
Australian Region 10 22242232
Cocos Island 8 22132321
Darwin 9 22242222
Townsville 11 32242232
Learmonth 12 32242332
Alice Springs 9 22242222
Gingin 11 2224232-
Canberra 10 22242232
Hobart 11 22342232
Estimated Antarctic Regional K Indices 20 Apr :
Macquarie Island 29 23374331
Casey 30 34432564
Mawson 58 34442586
Observed Regional daily pc3 Indices 20 Apr :
Darwin 0 (Quiet)
Townsville 2 (Quiet)
Learmonth 4 (Quiet)
Alice Springs 4 (Quiet)
Gingin 48 (Unsettled)
Canberra 68 (Active)
Melbourne NA
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 20 Apr : A
Fredericksburg 11
Planetary 12
Observed AFr/Ap Indices 19 Apr : A K
Fredericksburg 15
Planetary 20 4433 3334
2B. MAGNETIC FORECAST
Date Ap Conditions
21 Apr 10 Mostly quiet to unsettled, isolated active periods
possible
22 Apr 7 Quiet
23 Apr 12 Mostly quiet to unsettled, isolated active periods
possible
COMMENT: Quiet to active geomagnetic conditions were observed
in the Australian region on UT day 20 April. Quiet to storm levels
were observed in the Antarctic region. The observed elevated
geomagnetic activity is due to the coronal hole effects. On UT
day 21 April, geomagnetic activity is expected to be mostly at
quiet to unsettled levels with a possible isolated active period
due to the continued coronal hole effects. Mostly quiet conditions
on 22 April are expected and then quiet to unsettled conditions
with possible active periods on 23 April.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
20 Apr Normal Normal Normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
21 Apr Normal Normal Normal
22 Apr Normal Normal Normal
23 Apr Normal Normal Normal-fair
COMMENT: Mostly normal HF propagation conditions are expected
on UT days 21-22 April. Periods of minor degradation may be observed
on UT day 23 April at high latitudes.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
20 Apr 22
Observed Australian Regional MUFs
Cocos Island Region:
No data available.
Niue Island Region:
No data available.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Scott Base/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Mar 9
Apr 19
May 23
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
21 Apr 22 Near predicted monthly values
22 Apr 22 Near predicted monthly values
23 Apr 15 Near predicted monthly values
COMMENT: MUFs over the Australian regions were mostly near predicted
monthly levels on UT day 20 April. MUFs are expected to be near
predicted monthly values on UT days 21-22 April. Minor MUF depressions
are possible on UT day 23 April due to a possible rise in geomagnetic
activity.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 19 Apr
Daily Proton Fluence >1 MeV: 3.7E+05
Daily Proton Fluence >10 MeV: 4.1E+04
Daily Electron Fluence >2 MeV: 2.10E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:16%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B1.1
DSCOVR Satellite Solar Wind Day Averaged Data for 19 Apr
Speed: 619 km/sec Density: 5.6 p/cc Temp: 233000 K Bz: 0 nT
(Courtesy Space Weather Prediction Center, Boulder USA)
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Space Weather Services email: asfc at bom.gov.au
Bureau of Meteorology
PO Box 1386 WWW: http://www.sws.bom.gov.au
Haymarket NSW 1240 AUSTRALIA FTP: ftp://ftp-out.sws.bom.gov.au
tel: +61 2 9213 8010 fax: +61 2 9213 8060
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