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...but not by much. Jim, the ICESat domain was used for some comparisons in Laxton et al 2013; it seems no longer relevant, given that the new CS-2 data is much more extensive. Seems to me the problem with getting a realistic total volume estimate from CS-2 is mostly to do with the edges, where the thickness data drops out well inside the area / extent limits (at least in many pixels). That isn't going to be well-solved by any sort of masking; it needs an interpolation / extrapolation scheme.
Toggle Commented Apr 18, 2015 on CryoSat-2 sea ice thickness maps at Arctic Sea Ice
Thanks Neven. And the volume is? They're not saying, and the one published ref (Laxton et al 2013 in GRL -- on the data page) isn't all that helpful: "[16] Ice volume is computed using CS-2 over the 'ICESat domain' (Figure 1). The domain covers the central Arctic Ocean and has an area of 7.2 million km2. Values for grid cells north of the CS-2 latitudinal limit (88N for CS-2 and 86N for ICESat) are obtained by substituting values from the nearest grid cells that include thickness data. ... "[17] In common with earlier satellite radar altimeters CS-2 sea ice thickness estimates exclude open water. To compute sea ice volume, we therefore take the product of the area, the thickness excluding open water obtained from CS-2 and the ice concentration obtained from SSM/I [Meier et al., 2006]." and "[20] Table 1 shows the average ice volumes computed for the ICESat period and for the two CS-2 winters. Also shown is the change in ice volume between the two time periods for both the satellite and model estimates. We include the “unadjusted” ice volumes for comparison with K09 ... but consider the adjusted volumes as more representative since they account for changing ice concentration between the two periods." One is tempted to just multiply the CS-2 thickness by the Cryosphere Today area (which is already "concentration adjusted"), but that might be biased high because of the coverage differences?
Toggle Commented Apr 18, 2015 on CryoSat-2 sea ice thickness maps at Arctic Sea Ice
The earliest maximum snow depth in the 60-year Australian record happened last year: (a similar game of "will it or won't it" was played through that season). There is a clear trend to earlier maximums: Are earlier extremes a general effect of AGW on the cryosphere?
Toggle Commented Mar 19, 2015 on Early record, late record at Arctic Sea Ice
It's interesting that the ref's fig 5 (the second figure above) suggests a linear decline in average ice thickness in the central Arctic. That combined with a linear decline in average ice area (roughly as observed) would produce a quadratic decline in volume. Those who have been criticising 'arbitary' quadratic fits to the PIOMAS volumes might like to take note.
Toggle Commented Mar 6, 2015 on Thinner and thinner at Arctic Sea Ice
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Mar 5, 2015