Brief Communication: Mesoscale and submesoscale dynamics in the marginal ice zone from sequential synthetic aperture radar observations

Abstract

Abstract. New possibilities for horizontal current retrieval in marginal ice zones (MIZs) from sequential Sentinel-1 synthetic aperture radar (SAR) images are demonstrated. Daily overlapping SAR acquisitions within 70–85∘ S/N at time intervals < 1 h enable estimation of high-resolution velocity fields, revealing MIZ dynamics down to submesoscales. An example taken from the Fram Strait MIZ reveals energetic eddies and filaments with Rossby numbers reaching O(1) magnitudes. The SAR-derived velocity estimations at such high spatial resolution can be critical for monitoring the evolving MIZ dynamics and model validation of submesoscale processes in polar oceans.

Remote Sensing of Ice Conditions in the Southeastern Baltic Sea and in the Curonian Lagoon and Validation of SAR-Based Ice Thickness Products

“…The main advantage of the method is the ability of SAR to perform measurements under cloudy conditions and at night that are major limitations for the optical and infrared remote sensing in the Baltic Sea [30,31]. While being effective for observing surface pollutants and signatures of upper-ocean dynamics over ice-free regions mostly under low to moderate winds [32][33][34][35][36], SAR observations of sea ice patterns are feasible under a wider range of wind speeds [14,37], and were successfully used for the sea ice studies in the nearby Vistula Lagoon [38]. We also use cloud-free optical data from Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua satellites to illustrate the ice cover formation and decay in the Curonian Lagoon.…”

Eddies in the Marginal Ice Zone of Fram Strait and Svalbard from Spaceborne SAR Observations in Winter

“…The latter splits into two recirculation branches interacting with the cold EGC, and Svalbard and Yermak branches entering the Arctic Ocean (Figure 1). Such a close occurrence of the cold PW, the warm AW with very high levels of eddy kinetic energy [13,14,19], and the year-round MIZ creates very favorable conditions for intensive eddy generation [1,7]. Though previous studies in FS gained much information about eddy generation mechanisms, their spatial and kinematic properties and influence on sea ice, the obtained results were still episodic and resolving only a limited number of eddies.…”

“…Recent studies also show that polar MIZs are rich in submesoscale flows with high Rossby numbers and strong ageostrophic effects [5][6][7][8][9][10]. Submesoscale ocean variability induces large vertical velocities bringing warm subsurface waters into the mixed layer and results in pronounced ocean-sea ice heat fluxes localized over cyclonic eddies and filaments reaching about 100 W m −2 [8].…”

“…Though current state-of-the-art 1 km and finer resolution models potentially resolve small eddies in the MIZ and around sea ice leads [13], a realistic forecasting of meso-and submeso-scale MIZ dynamics is still challenging and needs a good observational basis for model improvement and validation. In this sense, satellite remote sensing using spaceborne synthetic aperture radar (SAR) is a good and effective source of information to explore and better understand the eddy field in the Arctic Ocean, including the ice-covered regions [1,3,7,10,[16][17][18][19]. What is especially good about SAR is that it can map MIZ dynamics, including eddy motions, under broad variety of wind speeds including high wind conditions [1,10].…”

Lagrangian Data Assimilation and Parameter Estimation of an Idealized Sea Ice Discrete Element Model

“…In fact, sea ice tracking techniques via automatic matching based on satellite-derived surface features have been developed recently using reflectance images at a resolution of 250 m, providing the observations of the locations and angular displacements for floes larger than about 5 km (Lopez-Acosta et al, 2019). Using the higher-resolution Synthetic Aperture Radar data with 20-60 m pixel size (Kozlov et al, 2020), it might be possible to track floes an order of magnitude smaller, but such datasets have not yet been developed but are expected to appear in near future. It is nevertheless important to note that the Eulerian sea ice models have their own desirable features.…”