Abstract's details
Sea ice classification, concentration and topography using SWOT
Event: 2025 SWOT Science Team Meeting
Session: Cryosphere: Sea Ice, SLA and glaciers
Presentation type: Oral
Sea ice plays a major role in climate, these changes are of great concern to scientists, who are seeking to forecast its behavior and understand their causes and effects. The most common techniques employed to monitor sea ice rely on 2D space imagery in a wide range of frequencies and techniques (optical, thermal, radiometric, SAR imagery). However, we now know that the evolution of sea ice over the course of days or seasons is governed more by its thickness than by its extent. Thickness is therefore an essential parameter to determine the condition of the ice and its ability to withstand particular climatic events (wind, heat waves) or oceanic events (waves, swells, upwelling of warm waters, etc.). Thickness also provides access to volume and mass variations, quantifying freshwater inflows and the effects of stratification on ocean circulation.
The main technique for measuring sea ice thickness is based on nadir altimeters. The result is a series of point measurements of the sea ice taken vertically along the satellite track. This loose sampling between tracks means that we have to wait for about a month of data to provide a sufficiently dense spatial representation to be exploitable. Relative to the current sparse observations, SWOT's scan width (120km) offers enormous potential to analyze sea ice conditions and dynamics on much shorter time scales and with much higher coverage and density.
This mission, whose primary objective is continental hydrology, was given little consideration by the sea ice scientific community, as we felt that the viewing angle (+- 2.7°) would not allow us to obtain feedback on water surfaces in highly specular sea ice fractures. Without this water reference, ice freeboard and thickness cannot be measured. But initial tests carried out by CNES on atypical surfaces, including sea ice, have revealed quality measurements not only on ice, but also in leads, albeit less systematically on these watery.
We have developed a technique that distinguishes between ice floes and open water in cracks in the ice (the leads) and in polynyas. This classification is now available in the CNES L3 250m v2 product distributed by AVISO. This makes it possible to measure the SLA in sea ice leads in continuity with the open ocean, as well as measuring the freeboard of the ice and, ultimately, its thickness. We propose to present the classification method developed, the first sea ice concentration maps derived from this classification, and the sea ice freeboards in both hemispheres. These results will be compared with reference products for sea ice concentration and sea ice freeboard to illustrate SWOT's strong potential for monitoring sea ice.
Back to the list of abstractThe main technique for measuring sea ice thickness is based on nadir altimeters. The result is a series of point measurements of the sea ice taken vertically along the satellite track. This loose sampling between tracks means that we have to wait for about a month of data to provide a sufficiently dense spatial representation to be exploitable. Relative to the current sparse observations, SWOT's scan width (120km) offers enormous potential to analyze sea ice conditions and dynamics on much shorter time scales and with much higher coverage and density.
This mission, whose primary objective is continental hydrology, was given little consideration by the sea ice scientific community, as we felt that the viewing angle (+- 2.7°) would not allow us to obtain feedback on water surfaces in highly specular sea ice fractures. Without this water reference, ice freeboard and thickness cannot be measured. But initial tests carried out by CNES on atypical surfaces, including sea ice, have revealed quality measurements not only on ice, but also in leads, albeit less systematically on these watery.
We have developed a technique that distinguishes between ice floes and open water in cracks in the ice (the leads) and in polynyas. This classification is now available in the CNES L3 250m v2 product distributed by AVISO. This makes it possible to measure the SLA in sea ice leads in continuity with the open ocean, as well as measuring the freeboard of the ice and, ultimately, its thickness. We propose to present the classification method developed, the first sea ice concentration maps derived from this classification, and the sea ice freeboards in both hemispheres. These results will be compared with reference products for sea ice concentration and sea ice freeboard to illustrate SWOT's strong potential for monitoring sea ice.