Sea Ice Deformation Is Not Scale Invariant Over Length Scales Greater Than a Kilometer.

In March and April 2021, buoys were deployed in the Beaufort Sea, Arctic Ocean, to measure sea‐ice horizontal deformation over spatial scales that had not been previously achieved. Geodetic‐quality position measurements allowed measurements of strain‐rate over lengths from about 200 m to 2 km. Conventional ice‐drifters extended spatial coverage up to about 100 km. Past studies find there is multi‐fractal behavior for horizontal sea‐ice deformation from 10 to 1,000 km. Our results demonstrate that such behavior does not hold when including spatial scales below 10 km. We find that sea‐ice deformation is not scale invariant between the scale of individual sea‐ice floes and aggregates of floes. Therefore, we cannot expect the same physical laws or forcing to describe sea‐ice kinematics over these regimes, nor can we assume log‐log linear behavior for mean deformation. Using this scaling behavior as a metric to validate models that resolve sea ice floes and their interactions is hence not recommended. Plain Language Summary: In March and April of 2021, a nested array of buoys was deployed around a drifting camp on sea ice 50 km off‐shore in the Beaufort Sea, Arctic Ocean. The inner buoys of the array measured their position with centimeter‐level accuracy allowing for measurements of sea ice deformation at a wide range of spatial scales. Sea ice deformation includes the opening and closing of the ice and shearing motion that occurs along cracks in the ice known as leads and ridges. This experiment was the first time that sea‐ice deformation has been analyzed over scales from 100s of meters to 100s of kilometers. Past studies over areas spanning more than 10 km suggest that the sea‐ice deformation has fractal behavior, a mathematical relationship where the rates of deformation increase as you measure over increasingly smaller regions. Past measurements of deformation over smaller areas found a different fractal behavior. In this study, we find that the mathematical relationship does not fit observations across any region larger than a kilometer square. We conclude that sea‐ice deformation is not fractal and caution against assuming that this relationship exists for climate and forecast modeling. Key Points: Results from the first field experiment measuring sea‐ice deformation across spatial scales ranging from 200 m to over 100 km are presentedPrevious studies indicate sea‐ice deformation is multi‐fractal for scales above 10 km, and we find this does not holdOver spatial scales from 1 to ∼100 km, deformation does not scale log‐log linearly with separation distance, and is not fractal [ABSTRACT FROM AUTHOR]