The METRAC Positioning System: A New Tool for Air Pollution Research and Operational Support

Abstract

Metrac is Control Data’s trade name for its ground-based radio location system. The positioning system makes use of the Doppler principle in order to track an inexpensive, expendable transmitter. The electronics required to implement the system consists of a lightweight balloon-borne transmitter, four or more receivers, and a central command console. A prototype system has recently been built and evaluated for the Environmental Protection Agency for possible use in the Regional Air Pollution Study Program. This paper presents a brief description of the system and some of the results of a field test of the prototype system conducted in Minneapolis. The field test consisted of a comparison of wind profiles derived from the system with wind profiles derived from simultaneous rawinsonde and theodolite tracking. The results presented In this paper demonstrate the great accuracy and high resolution of low level winds measured by the prototype system. The body of information presented in this paper is directed to air pollution meteorologists concerned with the transport and diffusion of atmospheric pollutants.