[Ips-hf-warning] IPS HF COMMS WARNING

[rwc]

SUBJ: IPS HF RADIO COMMUNICATIONS WARNING 01/16
ISSUED AT 31/2352Z MARCH 2001
BY THE AUSTRALIAN SPACE FORECAST CENTRE.

DEGRADED HF PROPAGATION CONDITIONS EXPECTED FROM 
01-02 APRIL 2001. MID LATITUDE STATIONS SHOW A STRONG 
DEPRESSION RESPONSE TO SEVERE OVERNIGHT GEOMAGNETIC ACTIVITY. 
STATIONS SOUTH OF BRISBANE ARE CURRENTLY DEPRESSED BY UP 
TO 50% AFTER LOCAL DAWN THIS MORNING.

THE SOLAR REGION MOSTLY RESPONSIBLE FOR RECENT FLARE 
ACTIVITY REMAINS FLARE CAPABLE. IF A SOLAR FLARE
OCCURS DURING LOCAL DAYLIGHT HOURS WITH THESE
DEPRESSED MUF CONDITIONS THE HF SPECTRUM COULD
BECOME UNAVAILABLE DURING THE FLARE EVENT.

LOW LATITUDE MUFs (DARWIN, VANIMO) HAVE SO FAR NOT
RESPONDED TO THE OVERNIGHT STORM AND COMMUNICATORS
WITHIN LOW LATITUDES CAN CONTINUE TO USE A T INDEX OF 
AROUND 120.

IF COMMS DIFFICULTIES EXPERIENCED TRY A LOWER FREQUENCY BAND
FOLLOW ON HF WARNING FROM HF WARNING: 15
-------------------------------------------------------------
SOLAR ACTIVITY FORECAST       HF COMMS FADEOUTS             
01 Apr:  moderate to high     Probable             
02 Apr:  moderate to high     Probable             

HF COMMUNICATIONS FORECAST (AUSTRALIAN/NEW ZEALAND REGION)
                                   FREQUENCY BANDS  
       T-index  MUFs          2  4  6  8 12 16 22 26
-------------------------------------------------------------
Southern region (mid to high latitudes):
01 Apr   30    -40%           2  4  4  4  8  8 12 12 
Northern region (low latitudes):
01 Apr  120    -15%           2  4  6  8 12 12 16 22 
02 Apr  100    -15%           2  4  6  8 12 12 16 22 

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