[Ips-hf-warning] IPS HF COMMS WARNING issued 0303 UT on 28 Mar 2012

[rwc]

SUBJ: IPS HF RADIO COMMUNICATIONS WARNING 12/19
ISSUED AT 28/0302Z MARCH 2012
BY THE AUSTRALIAN SPACE FORECAST CENTRE.

Degraded conditions have been observed for southern Aus/NZ regions 
so far today. Mildly degraded conditions are expected at times 
over the next few days for southern regions.

DEGRADED HF PROPAGATION CONDITIONS EXPECTED
FROM 28-30 MARCH 2012 FOR SOUTHERN REGIONS
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
_____________________________________________________________
28 Mar:   45          -15%      2  4  6  8 12 12 16 22
29 Mar:   45          -15%      2  4  6  8 12 12 16 22
30 Mar:   45          -15%      2  4  6  8 12 12 16 22

Note:
An IPS MUF depression HF Warning and IPS 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.

IPS Radio and Space Services        email: asfc at ips.gov.au
PO Box 1386                         WWW: http://www.ips.gov.au
Haymarket NSW 1240  AUSTRALIA       FTP: ftp://ftp.ips.gov.au 
tel: +61 2 9213 8010                fax: +61 2 9213 8060 

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