Arctic freeboard and snow depth from near-coincident CryoSat-2 and
ICESat-2 (CRYO2ICE) observations: A first examination during winter
2020-2021
Abstract
In the summer of 2020, ESA changed the orbit of CryoSat-2 to align
periodically with NASA’s ICESat-2 mission, a campaign known as CRYO2ICE,
which allows for near-coincident CryoSat-2 and ICESat-2 observations in
space and time over the Arctic. This study investigates the CRYO2ICE
radar and laser freeboards acquired by CryoSat-2 and ICESat-2,
respectively, during the full winter season of 2020–2021, and derives
snow depths from their differences. As expected, the ICESat-2 signal is
backscattered at a surface above the elevation of the CryoSat-2 signal.
CRYO2ICE snow depths are thinner than the daily model- or
passive-microwave-based snow depth composites used for comparison, where
differences are most pronounced in the Atlantic and Pacific Arctic.
These observations show the exciting potential for along-track
dual-frequency observations of snow depth from the future Copernicus
mission CRISTAL; but also highlight uncertainties in radar penetration
and the length scales of snow topography that still require further
research.