The Average Shape of Sea Ice Ridge Keels
Through analysis of over 64,000 ridge profiles identified from moored upward-looking sonars, we identify a well-defined average shape of pressure ridge keels that is concave or cusped, not triangular as widely assumed in other literature. On the basis of this average shape, we put forward a new, dimensional-definition, of a pressure ridge cross-section that follows a negative exponential form and allows an average pressure ridge cross section to be constructed with knowledge or choice of a single parameter. The horizonal asymptote of the profile represents the draft of the “background” ice in which the ridge is embedded. The draft of this background ice scales with keel depth and is typically greater than can be accounted through thermodynamic growth, indicating that ridges tend to be embedded in fields of mechanically thickened rubble. Using a variational ridge model we simulated keel shapes for a range of ridge building conditions. Here, the model results agree well with the observations and indicate the cusped shape of an average ridge profile arises from the varying angle of horizontal shear in the ice cover when ridges form. The modeling results also explain the elongated tail of the area draft distribution of the pack.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); Naval Academy Research Council (NARC); US Department of the Navy, Office of Naval Research (ONR)
- Grant/Contract Number:
- 89233218CNA000001
- OSTI ID:
- 1865017
- Report Number(s):
- LA-UR-21-26386
- Journal Information:
- Geophysical Research Letters, Vol. 48, Issue 24; ISSN 0094-8276
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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