Snowpack and freshwater ice sensing using Autocorrelation Radiometry

Abstract

Wideband Autocorrelation Radiometry (AR) offers a new approach to snowpack and freshwater ice sensing. AR snowpack sensing promises two-way microwave travel times, τ sp , attenuation, and sub-pixel τ sp variance in snowpacks. In combination with snowpack thermophysical models, AR offers a deterministic means of measuring snowpack Snow Water Equivalent (SWE), wetness, and sub-pixel SWE variance. AR sensing of freshwater ice promises two-way travel times in the ice layer and, thus, ice thickness. An AR sensor's frequency would lie below ∼15 GHz for increased sensitivity to wetness and decreased sensitivity to scatter darkening. Preliminary computer simulations show that: (1) A 10 GHz radiometer with a bandwidth of 1 GHz will resolve two-way snowpack travel times, τ sp , to uncertainties of <10 cm equivalent thickness, and (2) a multiply reflected AR signal exhibiting an attenuation 37 dB is readily detected. Wide bandwidth AR sensors will be subject to greater Radio Frequency Interference (RFI) than traditional radiometers, but communications-type RFI with high duty cycles, while raising the noise floor, will not affect AR interpretability.