J.S. Marshall Radar Observatory

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The J.S. Marshall Radar Observatory (or MRO) is a McGill University facility in Sainte-Anne-de-Bellevue, Quebec housing several weather radars and other meteorological sensors, many of them running around the clock.

1 Purpose
2 History
3 Main instrument
4 Other instruments
5 References
6 External links

[edit] Purpose

The main focus of the MRO is teaching and research. The group upgrades and designs radars, develops new ways to process the radar signals and uses the resulting data, and performs research on the physics of weather events and their prediction. Results of the research are published in scientific journals and transferred for use by the weather office.

[edit] History

In 1862, a first Weather Observatory was built by McGill University ^[1]. The instruments were donated by Dr. Charles Smallwood (MD) who had taken weather data personally since 1840 with them. This station became one of the first in the weather station network set up after the generalization of telegraph.

In 1943, Project Stormy Weather was assigned to J.S. Marshall in Ottawa by National Defense. The aim was to find a use for noise in radar echoes that had proved to be from weather. Marshall and his doctoral student Walter Palmer became later well known for their work on the drop size distribution in mid-latitude rain that led to the rain rate relation to radar reflectivity (Z-R relation). Just after the Second World War, Marshall and R.H. Douglas formed le « Stormy Weather Group ^[2]» in McGill University and continued their work.

Different radars were used by the Group to research the characteristics of precipitations at Dawson College continuing the tradition of meteorology at McGill. It was decided to build a new facility in 1968 in Sainte-Anne-de-Bellevue, on the western tip of the Montreal Island and to transfer all the group activity there. This new observatory was renamed later the J.S. Marshall Radar Observatory in honor of its founder.

[edit] Main instrument

CWMN tower and radome (Source: McGill University)

A 10 centimeters wavelength Doppler and dual-polarization radar built in 1968 and used for weather surveillance around the Montreal, Canada area. It is part of the Canadian weather radar network ^[3], used by the local weather office to monitor weather in real-time for a variety of applications, from severe weather detection to sewer flow forecasting.

Characterictics:

Its ICAO calling identifier is CWMN.
Its coordonnates are 45°25′30″N, 73°56′10″W at 50 m above sea level.
It has a large 9 meters (30 feet) diameter antenna transmitting impulses from a klystron.
Its tower is 25 m high.
It scans the atmosphere on 24 angles from 0.5 to 34.4 degrees above the horizon in 5 minutes.
It was originally recording only reflectivites, giving position and intensity of precipitations. In 1993, it was upgraded to treat Doppler data and thus estimate the motion of the drops. It was upgraded again in 1999 with a dual polarization capability which permit to directly identify the type of precipitations (rain, snow, hail, etc...).

[edit] Other instruments

Many other devices are operated by the MRO at the site or in other locations. These varies according to the research interests pursued. Some of them are or have been: