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Ice Edge
Robert Grumbine edited this page Oct 8, 2020
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- NRL/ECCC algorithm
- Hausdorff measure (Dhukovitz et al, 20NNN)
- Integrated Ice Edge Error (IIEE) (Goessling, 20NNN)
NRL/ECCC algorithm:
- Use the IMS 4 km ice mask (finest resolution currently available in NWS operations, 1 km is available from NSIDC)
- Locate ice edge points as the boundary between adjacent cells marked as having ice vs. no ice. This corresponds to 40% ice concentration.
- Locate ice edge points in the model output, using above/below 40% concentration.
- For all points on the model ice edge, find the minimum distance to a point in the analysis.
- Compute the rms of these distances
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- But exclude points which are unreasonably far apart (a variable in the method, 250 km for now) -- this excludes, say, points in the Sea of Okhotsk from degrading the score against points in the Bering Sea, and, especially, the Yellow Sea.
Hausdorff:
IIEE:
- Integrate area where model has ice but analysis doesn't, or where analysis does but model doesn't.
- 'have ice' may be defined by concentration levels.
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- For IMS, use 40%.
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- For concentration analyses, model and analysis can be assessed at any critical level. 15% is traditional for passive microwave concentrations for the edge. But 80% may be useful for the inner edge of the Marginal Ice Zone.