Supraglacial lake bathymetry automatically derived from ICESat-2
constraining lake depth estimates from multi-source satellite imagery
Abstract
We introduce an algorithm “Watta”, which automatically calculates
supraglacial lake bathymmetry along tracks of the ICESat-2 laser
altimeter. Watta uses photon heights estimated by the ICESat-2 ATL03
product and extracts supraglacial lake surface, bottom, corrected depth
and (sub)surface ice cover on a lake. These measurements are used to
constrain empirical estimates of lake depth from satellite imagery,
which were thus far dependent on sparse sets of in-situ measurements for
calibration. Imagery sources include Landsat OLI, Sentinel-2 and
high-resolution Planet Labs PlanetScope and SkySat data, used here for
the first time to calculate supraglacial lake depths. The algorithm was
developed and tested using a set of 46 lakes near Sermeq Kujalleq
(Jakobshavn) glacier in Western Greenland. Our results suggest that the
use of multiple imagery sources (both publicly-available and commercial)
in combination with altimetry-based depths, can move towards capturing
the evolution of supraglacial hydrology at improved spatial and temporal
scales.