Measuring the Temporal Autocorrelation Function of Backscattered X-Band Signals From the Ocean With TanDEM-X

Abstract:
The rapid temporal decorrelation of backscattered microwave signals from the ocean is one of the key effects that need to be taken into account in the optimization of air- or spaceborne along-track interferometric SAR (InSAR) system parameters for current and wave measurements. Existing knowledge of the signal autocorrelation function is based on Doppler bandwidths from scatterometer experiments, coherences of fixed-baseline InSAR data, and numerical simulations. We demonstrate how the continuously varying along-track distance between the two TanDEM-X satellites can be exploited for a high-resolution sampling of the magnitude of the actual autocorrelation function at a series of short time lags.