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Example 1: Grounded ridges surrounded by drifting ice floes

July 14, 2008

The two animations above are synchronous. The time between each frame is approximately 4 minutes.

The animation on the left is a timeseries of the unprocessed radar data. The animation on the right displays two layers of processed data. The first layer has been generated using a running pixel-wise mean filter over a 6-frame (~24-minute) window. Stationary ice floes will yield a stronger mean signal over time than moving ones and they appear cyan in the animation. The second layer is generated by calculating the pixel-wise standard deviation over the same window. Floes that move past a point will yield higher standard deviations and appear red in the animation. This layer also creates trails created by moving targets.

In this example, the landfast ice is in an advanced stage of break-up. Isolated grounded ridges are highlighted in cyan in the left animation. They also appear as cyan reflectors in the right animation. These remain remain in place while drifting ice floes pass around them on both sides. One ridge (highlighted in red) exhibits discontinuous motion, which we take as evidence of seafloor gouging taking place.

The animation below shows preliminary results from a target-tracking algorithm that will be used calculate velocities of drifting ice floes and to help identify floes exhbiting anomalous behavior possibly related to seafloor gouging. Blue dots in the animation indicate "normal" free-drifting floes that could be tracked for at least 50 frames. Red dots indicate floes that are stationary at some point during this time. In this example, not all floes that come to rest indicate gouging events, but this approach will allow to us identify potential sequences of radar data for further algorithm development.

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