[Ips-hf-warning] ASWFC HF DEPRESSION WARNING issued 0207 UT on 24 Mar 2024 [SEC=OFFICIAL]

[rwc]

SUBJ: ASWFC HF RADIO COMMUNICATIONS WARNING 24/32
ISSUED AT 0206UT/24 MARCH 2024
BY THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE.

A coronal hole wind stream inducing G1-G2 geomagnetic conditions 
has caused some depressions to Australian region maximum usable 
frequencies (MUFs). Further MUF depressions are expected by the end 
of UT day 24-Mar or early 25-Mar due to an anticipated geomagnetic 
storm.

DEGRADED HF PROPAGATION CONDITIONS EXPECTED
FROM 24-26 MARCH 2024
IF COMMS DIFFICULTIES EXPERIENCED TRY A LOWER FREQUENCY BAND
_____________________________________________________________

HF COMMUNICATIONS FORECAST (AUSTRALIAN/NEW ZEALAND REGION)
                                   FREQUENCY BANDS
       T-index      MUFs        2  4  6  8 12 16 22 26
_____________________________________________________________
24 Mar:   80   normal/-30%      2  4  6  6  8 12 16 16
25 Mar:   60          -30%      2  4  6  6  8 12 16 16
26 Mar:   70          -20%      2  4  6  8  8 12 16 16

Note:
An ASWFC MUF depression HF Warning and ASWFC shortwave fadeout 
HF Warning are both current. Shortwave fadeouts degrade 
lower shortwave radio frequencies first (through increased 
ionospheric absorption) and the usual strategy during shortwave 
fadeouts is to try a higher frequency. In contrast, during 
periods of ionospheric MUF depression, the upper frequencies 
are degraded first and the usual strategy is to use a 
lower frequency. 

In general use a lower frequency if you are having trouble
with your normal workable frequency.

If a shortwave fadeout occurs during a period when ionospheric 
MUFs are depressed the available HF bandwidth will be "squeezed", 
with increased absorption raising the lowest usable frequency 
and the ionospheric depression lowering the highest usable 
frequency. Under such conditions it is suggested that the 
HF communicator operates on the highest usable frequency, 
even though this may well be in fact lower than what is normally 
supported for that particular circuit.

Australian Space Weather Forecasting Centre
Bureau of Meteorology
ASWFC at bom.gov.au
www.bom.gov.au | www.sws.bom.gov.au