George Issac
Cloud Physics and
Severe Weather Research Division
Meteorological Service of Canada
Air traffic at airports can be considerably disrupted during winter
weather such as a snowstorm and freezing precipitation. De-icing
operations must commence, the total amount of traffic the airport can
handle is often reduced, and delays and flight cancellations are common.
In-flight icing is also a problem for aircraft on approach or taking off.
MSC is developing a Nowcasting system to help provide decision makers
(airport authorities, airline dispatch, ground de-icing crews, pilots,
etc) with real-time, accurate, and up-to-date weather information to help
alleviate the problems and to increase safety. The system is currently
called the Airport Vicinity Icing and Snow Advisor (AVISA). This system
uses numerical model data, pilot reports, ground sensor data
(precipitation, ceiling, visibility, winds, etc) as well as remote sensing
(satellite, radar, radiometer) information to provide the necessary
Nowcasts out to approximately 6 hours. Other countries are developing
similar systems and they will be briefly described and compared with
AVISA. The limitations and strengths of some of the component inputs
(e.g. model data, radar, radiometric, precipitation rate) will be
discussed using experiences from the Alliance Icing Research Study II
(AIRS2) which was conducted in the Ottawa-Mirabel area from 3 November
2003 to 12 February 2004. This project involved 5 research aircraft and
several airport Nowcasting systems which were installed at Mirabel.
Plans for future work will also be described including the difficulties
associated with designing the system products, and implementing it
operationally.