Horizontal Motion Field Observations with a Single Pulse Doppler Radar

Abstract

A generalized relationship is derived which relates an arbitrary horizontal wind field and the Doppler velocity field that results from its observation with a single horizontally directed radar. The relationship shows clearly how various elements of the horizontal wind field (velocity components and their space derivatives) combine to account for Doppler velocity variations with azimuth and range. The relationship also provides a basis for development of observational techniques for interpretation of the horizontal motion field from single pulse Doppler radar measurements. Two sample techniques are presented for interpreting Doppler measurements in terms of horizontal motion in echoes located some distance from the radar. The underlying assumption upon which both techniques are based is the quasi-stationarity of the motion field relative to a reference frame moving with the observed echo. The practicality of one of these techniques is demonstrated for a model wind field by computer simulation of the Doppler velocity field that would be observed by a single radar with representative measurement accuracy, and computer reconstruction of the original motion field from these simulated Doppler measurements. Subject to the validity of the underlying assumption, the results demonstrate the feasibility of determining the horizontal motion field in a remote echo from the observations of a single pulse Doppler radar. Means of testing the basic assumption are presented.