Event Detail

Event Type: 
Applied Mathematics and Computation Seminar
Date/Time: 
Friday, April 26, 2019 - 12:00 to 13:00
Location: 
STAG 160

Speaker Info

Institution: 
OSU, Earth, Ocean, and Atmospheric Sciences
Abstract: 

Horizontal deformation, divergence and shear, modifies the sea ice thickness distribution through ridging and lead opening. Hence it has profound effects on the survivability of pack ice in summer. However it is not realistically simulated in many climate simulations.

The scaling properties of sea ice deformation can be estimated with arrays of drifting buoys or by motion tracking between repeat satellite images. Horizontal deformation has multi-fractal scaling behavior. Deformation appears to be scale invariant over spatial scales of 10-1000 km and temporal scales of hours to a day. There is coupling between spatio-temporal scaling, and the scaling exponents are variable in space and time. Sea ice deformation displays coherence between scales of roughly 100 to 1000 km and synoptic time scales of days to weeks. The transition from a winter to spring ice pack is observed as a loss of coherence at greater than synoptic time scales, and changes in coherence are related to weather. At smaller spatio-temporal scales coherence is lost, with deformation below 10km tending to a white noise process. The lack of coherence at small scales and larger scale coherence in winter suggests it is inappropriate to think of sea ice deformation as having a decorrelation length scale. Localization of deformation is observed to retain its character over the winter-spring transition. This has implications for model parameterization of thickness redistribution.

Two future field experiments will extend our knowledge to smaller scales and also identify physical mechanisms that may be associated with transitions in these scaling properties. These relationships will be discussed in the context of our current understanding of rheological models relating sea ice stress and strain rate.