[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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