The Stormy Weather Group

As radar technology improved during World War II with the reduction of the wavelength used in radars (smaller wavelength implies smaller radar units that can be put on vehicles and on aircrafts), large blobs of echoes appeared that had the effect of masking the aircraft echoes! It was soon discovered that these echoes were due to precipitation. As a result, the Canadian Army Operational Research Group started project Stormy Weather in 1943 with J. Stewart Marshall at its head. The group was moved to McGill after the war and became the Stormy Weather Group.

Early on, considerable effort was spent documenting the various observations made by the group's radar, as well as theoretical work on scattering, attenuation and the statistics of weather echoes. In the 1960s, work focussed on the study of hail formation (particularly in Alberta) using radar observations and laboratory experiments. With the advent of more powerful computers, numerical modelling was added to the arsenal of tools for understanding precipitation processes. [A good description of the work done during this period can be found in Douglas (1990)]

In 1968, the current facility was inaugurated. By the mid-70s, digital technology had made enough progress that it became possible to record and process radar imagery with computers. Considerable work was made to allow the presentation of horizontal and vertical cuts in precipitation, as well as tracking of echoes so that short term forecasts could be made.

Using the expertise gained, a lot of effort was put in the 1980s in supplying radar hardware and data processing software worldwide. Radars were built for Canada (for forestry applications), Hong Kong, Brazil; processors were added to radars in Canada, China and at Cape Canaveral. The combination of radar and satellite estimations of rainfall was also attempted, and research was also done in hydrology and in the study of fractal structure of precipitation.

Additional remote sensing capability was added in the 1990s: Dopplerization of the main scanning radar and addition of a second wavelength (X-band), addition of a profiler with RASS, ceilometer, vertically pointing radar, bistatic receivers and dual-polarization capability. Hence work focussed on the study and the use of these new instruments. In addition, research continued in hydrology, the effect of weather on microwave communications, and retrieval of the wind field using a single radar.

In the 2000s, a VHF profiler was added to our instrumentation. In an attempt to pave the way for the assimilation of radar data into numerical models, much work was done on the characterization of radar measurement errors, precipitation microphysics and its modeling, nowcasting and short term forecasting, and data assimilation itself.



Douglas, R.H., 1990. The Stormy Weather Group (Canada). In Radar in Meteorology, D. Atlas (Ed.), Amer. Meteor. Soc., 61-68.

Marshall, J.S., 1968. Three McGill Weather Observatories.

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