“…We next defined and computed a new metric, which we refer to as the extinction depth index,
:
where Z SD is the Secchi depth, and Z ref is the reference depth at the same location, with the latter obtained from the ETOPO2022 data set. Because previous studies have shown that ICESat‐2 is generally capable of bathymetric measurement to ∼1 Secchi depth (Parrish et al.,
2019; Watkins et al.,
2023), the dimensionless ratio ( ζ e ) can be thought of as an ICESat‐2 bathymetric retrievability index: where ζ e ≥ 1, the seafloor should be detectable by ICESat‐2. Next, we calculated an overall score for bathymetric retrievability by: (a) performing a binary reclassification on the monthly extinction depth ratio raster data sets to be one (a) for cells with a ratio greater than or equal to 1.0 and zero (0) for cells less than 1.0; (b) summing the monthly reclassified rasters; and (c) dividing the sum by 12.…”