[Ips-hf-warning] IPS HF COMMS WARNING issued 0548 UT on 23 Jun 2015

[rwc]

SUBJ: IPS HF RADIO COMMUNICATIONS WARNING 15/20
ISSUED AT 0548UT/23 JUNE 2015
BY THE AUSTRALIAN SPACE FORECAST CENTRE.

CME arrival just before 18UT/22Jun has resulted in minor geomagnetic 
storm levels. Another CME from the recent M6.5 flare on 22Jun 
is expected to impact the Earth over the next 24-36 hours. Degraded 
HF conditions are likely in association with this activity and 
to continue into 25 June.

DEGRADED HF PROPAGATION CONDITIONS EXPECTED
FROM 23-25 JUNE 2015
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
_____________________________________________________________
23 Jun:   40          -17%      2  4  6  8  8 12 16 22
24 Jun:   40          -17%      2  4  6  8  8 12 16 22
25 Jun:   40          -17%      2  4  6  8  8 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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