[Ips-dsgr] SWS Daily Report - 21 April 21 issued 2330 UT on 21 Apr 2021
Regional Warning Centre
rwc at ips.gov.au
Thu Apr 22 09:30:09 EST 2021
SUBJ: SWS DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/21 APRIL 2021 BY Space Weather Services
FROM THE AUSTRALIAN SPACE FORECAST CENTRE
SUMMARY FOR 21 APRIL AND FORECAST FOR 22 APRIL - 24 APRIL
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
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1A. SOLAR SUMMARY
Activity 21 Apr: Low
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 21 Apr: 78/17
1B. SOLAR FORECAST
22 Apr 23 Apr 24 Apr
Activity Low Low Low
Fadeouts Possible Possible None expected
10.7cm/SSN 80/20 78/17 78/17
COMMENT: Solar activity was low on UT day 21 April. There are
currently three numbered regions on the visible disk, AR2816,
AR2817 and AR2818. There were a series of B-class flares and
one C1.5 flare at 0129UT from region 2817. A narrow CME was associated
with this C1.5 flare off the Western limb of the Sun but does
not appear to have any geoeffective component. No other earthward
directed CMEs were observed. Solar activity is expected to be
low for the next three UT days, 22-24 April with some possibility
of C-class flares during this period and a slight possibility
of an isolated M-class event on 22 and 23 April. On UT day 21
April, the solar wind speed followed a decreasing trend from
570 km/s down to 465 km/s due to waning coronal hole effects.
The IMF (Bt) peaked at 5 nT and the north-south IMF (Bz) range
was +3/-4 nT. The solar wind speed is expected to continue gradually
decreasing on UT day 22 April. 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 again.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 21 Apr: Quiet to Unsettled
Estimated Indices 21 Apr : A K
Australian Region 5 12232001
Cocos Island 3 12221001
Darwin 4 12221011
Townsville 5 12232001
Learmonth 5 12222012
Alice Springs 4 02232001
Gingin 5 12222112
Canberra 4 02232001
Hobart 6 22232101
Estimated Antarctic Regional K Indices 21 Apr :
Macquarie Island 6 12242000
Casey 11 34332112
Mawson 23 34542225
Observed Regional daily pc3 Indices 21 Apr :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 8 (Quiet)
Canberra 15 (Quiet)
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 21 Apr : A
Fredericksburg 7
Planetary 8
Observed AFr/Ap Indices 20 Apr : A K
Fredericksburg 10
Planetary 12 3422 2233
2B. MAGNETIC FORECAST
Date Ap Conditions
22 Apr 7 Mostly quiet to unsettled, isolated active periods
possible during late hours
23 Apr 12 Quiet to unsettled with possible active periods
24 Apr 10 Quiet to unsettled with possible active periods
COMMENT: Quiet to unsettled geomagnetic conditions were observed
in the Australian region on UT day 21 April. Quiet to active
levels with one minor storm period were observed in the Antarctic
region. On UT day 22 April, geomagnetic activity is expected
to be initially at quiet to unsettled levels due to waning coronal
hole effects. Then mostly quiet to unsettled conditions with
possible active periods are expected from late on UT day 22 April
through UT days 23-24 April.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
21 Apr Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
22 Apr Normal Normal Normal
23 Apr Normal Normal Normal-fair
24 Apr Normal Normal Normal-fair
COMMENT: Mostly normal HF propagation conditions are expected
on UT day 22 April. Periods of minor degradation may be observed
on UT days 23-24 April at high latitudes.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
21 Apr 15
Observed Australian Regional MUFs
Cocos Island Region:
No data available.
Niue Island Region:
No data available.
Northern Australian Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
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
22 Apr 20 Near predicted monthly values
23 Apr 10 Near predicted monthly values/depressed 10 to
20%
24 Apr 15 Near predicted monthly values/depressed 10 to
20%
COMMENT: MUFs in the Australian region on UT day 21 April were
mostly near predicted monthly values with some mild depressions
in the Northern Australian region during the local night. MUFs
are expected to be near predicted monthly values on UT day 22
April. Minor to mild MUF depressions are possible on UT days
23-24 April due to a possible rise in geomagnetic activity.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 20 Apr
Daily Proton Fluence >1 MeV: 2.1E+05
Daily Proton Fluence >10 MeV: 4.2E+04
Daily Electron Fluence >2 MeV: 4.70E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:23%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B1.9
DSCOVR Satellite Solar Wind Day Averaged Data for 20 Apr
Speed: 605 km/sec Density: 5.9 p/cc Temp: 268000 K Bz: -1 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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