Potential Application of the Harmony for Sea Ice Model Validation

Sea ice in the Arctic Ocean is in continuous motion under the influence of wind, ocean, and internal stress. Sea ice deformation (computed as a spatial derivative of the drift field) is localized in space and time and forms elongated, narrow zones, also called Linear Kinematic Features (LKFs). The frequency distribution of deformation rates as well as the pattern, density, orientation, and intersection angle of LKFs are a characteristic feature of sea ice. Sea ice drift and deformation can be observed by pattern matching techniques applied to passive microwave, or scatterometer, or synthetic aperture radar (SAR) satellite data. The disadvantage of the type of ice drift product is the large time delta required between the image acquisitions, and a relatively low spatial resolution.

Harmony is a candidate for the Earth Explore 10 mission. The two Harmony satellites will fly in a reconfigurable formation with Sentinel-1D. Both will be equipped with a multi-angle thermal infrared sensor and a passive radar receiver, which receives the reflected Sentinel-1D signals using two antennas. In the stereo formation, the Harmony satellites will fly approximately 300 km in front and behind Sentinel-1, which allows for the estimation of instantaneous sea-ice drift vectors. As it was shown by Kleinherenbrink et al., [2021] the sea ice drift and deformation can be derived from simulated Harmony data, but the signal-to-noise ratio is quite low.

The goal of this study is to evaluate the applicability of the Harmony data for statistical characterisation of sea ice deformation in the Arctic Ocean and feasibility in utilisation for tuning parameters of the next generation sea ice model (neXtSIM, [Olason et al., 2022]). NeXtSIM can realistically simulate the sea ice motion and deformation. Both the LKFs and the spatial scaling of the sea ice deformation rate simulated by neXtSIM compare quite well to PMW and SAR observations. Sensitivity of synthetic Harmony data to neXtSIM rheological parameters is studied. A scenario of model validation against instantaneous sea ice drift satellite estimates is suggested.