Dry snowpack and freshwater icepack remote sensing using wideband Autocorrelation radiometry

Abstract

A recently developed microwave radiometric technique, known as wideband autocorrelation radiometry (WiBAR), offers a deterministic method to remotely sense the propagation time τ delay of multi-path microwave emission of low-loss terrain covers and other layered surfaces. Terrestrial examples are the snow and lake ice packs. The microwave propagation time τ delay through the pack yields a measure of its vertical extent. We report measurements of the icepack on Lake Superior, and the snowpack at University of Michigan Biological Station (UMBS) in winter 2014 and 2015, respectively. The observations are done at frequencies from 7 to 10 GHz for icepack and 1 to 3 GHz for snowpack. At these frequencies, the volume and surface scattering are small in the packs. This technique is inherently low-power since there is no transmitter as opposed to active remote sensing techniques. In this paper the system design parameters of the WiBAR is discussed and it is shown that the microwave travel time within a dry snow pack and lake ice pack can be readily measured for a wide range of layer thicknesses observed during the experiment.