Photos: Aircraft on weather patrol

The fleet operated by Mesaba Airlines, a Northwest Airlink partner based in Eagan, Minn., includes new Saab 340 cabin class turbo-props. Manufactured by Saab Scania Aerospace, this commuter plane was chosen for use in the Great Lakes Fleet Experiment--a survey designed to test new weather-data technology--because it makes short flights at relatively low altitudes. Those factors increase the number of data readings in parts of the atmosphere that are important for meteorological surveys.

The Great Lakes Fleet Experiment was part of a weather safety initiative sponsored by NASA called Tropospheric Airborne Meteorological Data Report, or TAMDAR, whose focus was to test an inexpensive instrument that would measure meteorological variables. Sixty-four Saab 340s were equipped with TAMDAR devices. TAMDAR flights began Sept. 21, 2004, and continued through November 2005.