Keep Watching the Skies

Improved weather forecasting is on Isztar Zawadzki’s radar. Literally.

By Mark Reynolds

From high atop Burnside Hall on McGill’s downtown campus, atmospheric studies researcher Isztar Zawadzki collects weather data that plays a crucial role in everything from municipal storm sewer management to air travel safety. <em>Credit: Rachel Granofsky</em>
From high atop Burnside Hall on McGill’s downtown campus, atmospheric studies researcher Isztar Zawadzki collects weather data that plays a crucial role in everything from municipal storm sewer management to air travel safety. Credit: Rachel Granofsky

Weather forecasting can be a matter of life and death. In a year that saw tens of thousands of deaths in Burma from the cyclone Nargis, that would seem to be an obvious statement, but too often Canadians forget that too much rain at the wrong time can kill. Take a sudden summer deluge that hit Montreal in 1987: Basements, streets and the Metro system were flooded—and a man died when his car was submerged in a flash flood on the Decarie expressway.

Isztar Zawadzki warns that we’re building a world where we will need to worry more about weather. “As our population increases, our need for understanding grows and our need for information grows,” he says.

As director of McGill’s J.S. Marshall Weather Radar Observatory, Zawadzki is there to provide that information. The City of Montreal, for example, uses data from Zawadzki’s facility in Ste. Anne de Bellevue to help manage its run-off and sewer systems. This sort of direct application of high-end research work is what has always driven Zawadzki. He came to Canada from Argentina in the 1960s for a nine-month training period, studying under McGill’s James Stewart Marshall. As the head of a World War II government task force on radar called, appropriately, Stormy Weather, Marshall was one of the first to see beyond the immediate aircraft-spotting applications of radar. After all, wars come and go, but weather is forever.

Stranded by a coup back home, Zawadzki has been in Montreal ever since, and is now in charge of the institute at which he was once a student. His “lab” has been based near the Macdonald Campus since 1968. The most visible part of the observatory is the 30-metre tower topped with what looks like a giant golf ball, 12 metres in diameter. Within this spherical wind shield is the rotating nine-metre dish of the S-Band Doppler weather radar, the largest such instrument in Canada.

As a physics student in Buenos Aires, Zawadzki entered into atmospheric studies because, he says, “I wanted to do something socially useful,” adding self-deprecatingly, “I was young.”

At the time, a great deal of research in the field was directed to understanding the formation of hail, with a view to limiting its devastating effects on crops. Zawadzki’s work continues to focus on freezing precipitation—and continues to be socially useful.

Zawadzki explains that, counter to what one may think, water can exist in the upper atmosphere in liquid form even in temperatures of minus 20 Celsius. It can co-exist with ice crystals in clouds, and the dynamics of the different forms of liquid within air currents can drastically change the nature of the precipitation that results.

“These ice crystals can grow by aggregation, if they collide with each other, or by collecting super-cooled water,” he says.

His research aims, in part, to develop algorithms that will allow radar installations to better distinguish between the varieties of ice crystals and super-cooled water in the atmosphere. This will allow forecasters to better predict whether sleet, hail, snow, freezing rain or some unholy combination thereof is on the way.

The team at J.S. Marshall, in addition to the brainpower they offer, is also in the hardware business. In a throwback to the do-it-yourself spirit that characterized Marshall’s Stormy Weather days, it created vertical pointing radar hardware and software, designed to probe the atmosphere for mixes of ice and water. A version of this innovative device, designed to spot snow and super-cooled water vapour, is currently being tested for Pearson International Airport in Toronto.

“Aircraft flying in such conditions are in danger of collecting super-cooled water that will subsequently freeze, with ice building up on the wings, which causes them to lose lift,” says Zawadzki. Icing is implicated in several large and small aircraft accidents every year, and may have been a factor in a fatal crash of a small cargo plane in Manitoba in 2006.

Zawadzki’s research horizons are extending considerably beyond the 300-kilometre radius of the J.S. Marshall’s radar range. The McGill radar group is the only Canadian participant in the American Collaborative Adaptive Sensing of the Atmosphere (CASA) project, which aims to revolutionize the way weather data are gathered and reported. Weather radar’s greatest weakness is their over-sampling of the upper atmosphere; the curvature of the Earth prevents most radars from making effective observations sufficiently close to the surface. To counter this, the CASA project, which is funded by the National Science Foundation and led by the University of Massachusetts, aims to develop a network of high-density, low-cost radars that provide localized data that can accurately paint the bigger weather picture, filling in those hard-to-reach corners of the lower atmosphere that the broad brush of traditional radar can’t reach.

Zawadzki and two assistant professors in the Department of Atmospheric and Oceanic Sciences, Frédéric Fabry and Pavlos Kollias, are currently doing research on a CASA test bed in Oklahoma, and operate a test radar in Amherst, Massachusetts, but the team has bigger ambitions. Zawadzki believes that Canada should become a full partner in the CASA project. While the benefits from intellectual property rights are one incentive—the McGill team is already working with Raytheon, a major American technology conglomerate—the new technology could well be adapted to observe northern weather.

“The whole idea is to build a Canadian test bed, so we can develop this system for Canadian conditions,” he says.

Zawadzki is quick to point out that McGill’s weather watching has immediate and useful applications. In addition to the City of Montreal’s patronage, much of the observatory’s operating budget is paid for by Environment Canada, for which the station provides data. When researchers at the Ste. Anne de Bellevue facility developed a new algorithm for short-term precipitation forecasts, the government agency was able to incorporate it into its operations relatively quickly.

“It goes from fundamental to applied research very quickly,” says Zawadzki. “Whatever research we do leads to operational use in a very short period.”

This research is funded by Environment Canada, with additional funding from the Natural Sciences and Engineering Research Council of Canada and the Canadian Foundation for Climate and Atmospheric Sciences.

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