Temporal decorrelation of X-band backscatter from wind-influenced vegetation

Abstract

The tenporal decorrelation characteristics of X-band Radar backscatter from wind-influenced vegetation were investigated using a short-range CW radar. Radar reflectance data were gathered on varlous types of individual trees from a distance of approximately 30 m The windspeed was mnitored during each measurement, which lasted 5 s. The crown cover and the mean leaf area of the trees were also recorded. Autocovariance plots were generated for each measurement, from which the decorrelation time was estimated. As expected, the return signals decorrelated faster at higher wind speeds. However, the decorrelation time was also found to depend on the tree type, tree structure, and l e d cover characteristics. Measured decorrelation times for d e r a t e winds (7-9 d s ) were often between 40-60 ms, although the lowest decorrelation time measured under these conditions was 14 ms for the Eastern Cottonwood. In lighter winds (1-4 d s ) , decorrelation times were much longer, and there was substantial spread in the data

Gpu-Based ω-K Tomographic Processing by 1d Non-Uniform FFTS

“…Finally, in order to test the algorithm stability against sources of temporal decorrelation, a different data set has been acquired with a fan artificially producing wind with a windspeed of about 2 m/s [46]. As it can be seen from Figure 10, the performance of the algorithm are robust, being the cross sectional shape of the tree still visible, although some sidelobes appear to be "attenuated" as the scatterers move during the data acquisition.…”

Backscattering From Trees Explained by Random Propagation Times

“…Corresponding power spectral densities were computed by the same authors in [14]. We will show that experiments described in [1] can be represented in a system of coordinates which is better fitted than the Wong model. .…”

“…Even better models can be found. For example, we have sampled and drawn the figures in [1] in the system of coordinates…”

“…Experiments in [1] were done in the University of Nebraska East Campus of Lincoln in the year 1990. The radar wave was in the X-band (8 GHz) in VV polarization, and backscatter on tree crowns was studied.…”

“…This process was successfully applied in other domains of propagation like acoustics, ultrasonics, or sea return [6]- [8]. In a first stage, we revisit the paper by Narayanan et al [1]. We show the benefits obtained by changing the coordinate axes in figures related to experiments in the X-band.…”