Wideband Autocorrelation Radiometry for Lake Icepack Thickness Measurement With Dry Snow Cover

Abstract

Wideband autocorrelation radiometry (WiBAR) is a recently developed microwave radiometric technique to measure the lake icepack or snowpack thickness. This technique offers a direct method to remotely measure the microwave propagation time difference of multipath microwave emission from low-loss layered surfaces such as dry snowpack and freshwater lake icepack. The microwave propagation time difference through the pack yields a measure of its vertical extent. However, the lake icepack thickness measurement can be affected by the presence of a dry snowpack, which introduces another multipath interference. We present a simple geophysical forward model considering this effect and derive the WiBAR system requirements needed to correctly measure the icepack thickness. An X-band instrument fabricated from commercial-off-the-shelf (COTS) components is used to measure the thickness of fresh water lake ice at the University of Michigan Biological Station. The WiBAR was able to directly measure the icepack of about 36 cm with a snowpack of about 4 cm on top at incidence angle of 69.4° with an accuracy of 2 cm.