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Power tools for studying the atmosphere

With SCISAT, a team of Canadian and international scientists will advance our understanding of the depletion of the ozone layer. SCISAT will concentrate on changes occurring over Canada, especially the Arctic.

There are two powerful scientific instruments on board SCISAT: a Fourier Transform Spectrometer (FTS) instrument and the MAESTRO instrument, for "Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation."

Comparing the data gathered by MAESTRO with that from the FTS instrument will help scientists determine the levels of aerosol in the atmosphere, which is crucial to understanding why and how fast the ozone layer is depleting.

Power tool #1: The Fourier Transform Spectrometer

The FTS instrument, built by ABB Bomen of Quebec, is designed to simultaneously measure the temperature, trace gases, thin clouds and aerosols found in the atmosphere using a solar occultation technique. For this technique to work, the orbiting satellite must first point to the Earth's horizon during sunrise or sunset. As the sun "moves" through the thin band of atmosphere at the horizon, its rays are partly absorbed by the various gases in the atmosphere at different altitudes.

Thus, as the FTS observes the rising or setting sun, it can perform its measurements throughout the whole thickness of the atmosphere and the quantity of produced aerosols and gases ejected by volcanoes is measured. The FTS will data will complement data from its traveling companion, the MAESTRO instrument.

Power tool #2: MAESTRO

MAESTRO's primary scientific goal is to provide high-resolution data on the atmosphere and precise profiles of ozone concentration.

Its other tasks include measuring the amounts of organic and inorganic particles under polar ozone holes and near large tropospheric pollution sources. The troposphere is the portion of the atmosphere that lies between the Earth's surface and an altitude of approximately 15 km. It consists of water vapour, gases, and vertical winds that account for much of our weather.

It was developed by the Meteorological Service of Canada, the University of Toronto, and EMS Technologies of Ottawa, and the Canadian Space Agency. Dr. Tom McElroy, of Environment Canada, and Dr. Jim Drummond of the University of Toronto, head the MAESTRO team.