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Example 2: Abrupt deceleration of drifting ice floe

August 5-6, 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.

This is a relatively rare example of sea ice incursion into the coastal zone in August. The sea ice is composed of small, loosely pack floes. There is little rigid body motion exhibited and targets act largely as independent particles. However, convergence of ice floes leads to the creation of two grounded ridges, which remain stationary temporarily before being dislodged. This action may also indicate a seafloor gouging event.

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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