Attenuation of waves in pancake ice: multi-wave-buoy in situ measurements compared with a two-layer viscous model

We present results from the deployment of a six wave-buoy array into the advancing pancake ice zone of the Weddell Sea in April 2000. The buoys contained a vertical accelerometer and reported the 1-D wave spectrum at 3 hour intervals from their deployment until the pancake ice cover finally consolidated into the familiar pack ice - a period of ~15 days. We choose instances where two or more buoys are lined up in the direction of the incoming oceanic wave propagation direction (derived from the ECMWF WAM model) and calculate the spectral attenuation coefficient between them. These results are then compared with a two-layer viscous wave model. Assuming definite ice layer thicknesses from in situ measurements, the attenuation rates as a function of the wave period were fitted to obtain estimates of the ice and water viscosities.