[Ips-hf-warning] IPS HF COMMS WARNING

[rwc]

SUBJ: IPS PRELIMINARY HF RADIO COMMUNICATIONS WARNING 01/02
ISSUED AT 29/0016Z JANUARY 2001
BY THE AUSTRALIAN SPACE FORECAST CENTRE.

M1 SOLAR XRAY FLARE OBSERVED AT 1603 UT ON 28 JAN. EVENT WAS 
ASSOCIATED WITH A CORONAL MASS EJECTION AND A PROTON EVENT WHICH BEGAN 
AT 2045UT ON 28 JAN. THE MAIN MASS EJECTION DIRECTION APPEARED 
TO BE BIASED MORE WESTWARD, WITH SOME FRACTION EARTHWARD DIRECTED. 
THE M1 FLARE WAS FROM A DECAYING REGION IN THE FAR SOUTHWEST QUADRANT 
OF THE SOLAR DISK.

DEGRADED HF PROPAGATION CONDITIONS ARE EXPECTED FROM 29 JANUARY 2001 TO 01 
FEBRUARY 2001 MID TO HIGH LATITUDES ONLY.

INCREASED ABSORPTION HAS BEEN OBSERVED AT HIGH LATITUDES (POLAR REGIONS) 
SINCE PROTON EVENT ONSET AT 2045UT ON 28 JAN. ABSOPRTION EXPECTED TO EASE 
LATER ON 29 JAN. HIGH LATITUDE HF CONDITIONS ARE EXPECTED TO IMPROVE
ON 30 JAN. MID LATITUDE MUFS EXPECTED TO BE NEAR NORMAL 29-30 JAN.

HF CONDITIONS ARE THEN EXPECTED TO BECOME DEGRADED FOR BOTH MID TO HIGH
LATITUDES LATER ON 31 JAN TO 01 FEB IN ASSOCIATION WITH ANTICPATED
INCREASE IN GEOMAGNETIC ACTIVITY EXPECTED ON 31 JAN FROM THE M1 CME EVENT.

IF COMMS DIFFICULTIES EXPERIENCED 31 JAN TO 01 FEB AT MID LATITUDES TRY 
A LOWER FREQUENCY BAND.
A MORE DETAILED HF WARNING WILL FOLLOW IF DISTURBANCE AT 
MID LATITUDES EVENTUATES.
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IPS Radio and Space Services      | email: asfc at ips.gov.au
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