'Institute of Electrical and Electronics Engineers (IEEE)'
Abstract
Uncertainty in snow properties impacts the accuracy
of Arctic sea ice thickness estimates from radar altimetry. On firstyear sea ice (FYI), spatiotemporal variations in snow properties
can cause the Ku-band main radar scattering horizon to appear
above the snow/sea ice interface. This can increase the estimated
sea ice freeboard by several centimeters, leading to FYI thickness
overestimations. This study examines the expected changes in Kuband main scattering horizon and its impact on FYI thickness
estimates, with variations in snow temperature, salinity and
density derived from 10 naturally occurring Arctic FYI Cases
encompassing saline/non-saline, warm/cold, simple/complexly
layered snow (4 cm to 45 cm) overlying FYI (48 cm to 170 cm).
Using a semi-empirical modeling approach, snow properties from
these Cases are used to derive layer-wise brine volume and
dielectric constant estimates, to simulate the Ku-band main
scattering horizon and delays in radar propagation speed.
Differences between modeled and observed FYI thickness are
calculated to assess sources of error. Under both cold and warm
conditions, saline snow covers are shown to shift the main
scattering horizon above from the snow/sea ice interface, causing
thickness retrieval errors. Overestimates in FYI thicknesses of up
to 65% are found for warm, saline snow overlaying thin sea ice.
Our simulations exhibited a distinct shift in the main scattering
horizon when the snow layer densities became greater than 440
kg/m3
, especially under warmer snow conditions. Our simulations
suggest a mean Ku-band propagation delay for snow of 39%,
which is higher than 25%, suggested in previous studies