The use of level singular value decomposition techniques for vector velocity determinations and its application to tid observations

Building on previous work related to a determination of dynasonde phase parameters, we have obtained <2° standard deviation in the measured echo phases from an instrument at Bear Lake Observatory in Utah. These small uncertainties in phase measurement enable high-resolution echolocation components and line-of-sight Doppler velocity to be obtained. The purpose of this paper is to describe a level singular value decomposition technique to determine either the full vector velocity versus height or the plasma frequency in the ionosphere. Each three-dimensional velocity vector may be derived by a best fit to a set of echolocation components and Doppler velocities of spatially distributed echoes in independent steps over a frequency range of 0.2 MHz. Previous work has shown that ionospheric echoes in spread F can be used to derive a vector velocity that can be attributed to the flow of F-region plasma; in this work, data from the mid-latitude ionosphere are analyzed, which suggest that the three-dimensional phase motion of atmospheric gravity waves is responsible for the wave-like features that are observed