Ice Sensing Algorithms for Argo floats in the European Arctic

Argo floats operating in seasonal ice zones may be damaged when encountering sea ice during ascend or while parking at the surface. Therefore, Klatt et al., (2007) developed an Ice Sensing Algorithm (ISA) as an ice avoidance strategy. It uses temperature data measured by the float during ascend to determine the presence of sea ice above it. Ice detection triggers the interruption of the ascending trajectory, avoiding collision and increasing the floats lifetime. Near to freezing point temperatures have been successfully used as ice detection threshold in the Southern Ocean. However, the ISA parameters must be locally tuned for floats operating in northern high latitudes like the European Arctic, where the under-ice water properties are more variable mainly due to the inflow of warm Atlantic water close to the surface.

Within MOCCA (Monitoring the Oceans and Climate Change with Argo), a Euro-Argo ERIC project co-founded by the European Maritime and Fisheries Fund (EMFF), the initial steps to extend the float coverage into the European Arctic were taken. In preparation for float deployments in the region, hydrographic measurements from the Unified Database for Arctic and Subarctic Hydrography database (UDASH, Behrendt et al., 2018) and multi-sensor sea ice extent maps from the National Snow and Ice Data Center (MASIE-NH) were used to locally tune the ISA algorithm for the Barents Sea. The algorithm performance for this and other regions is assessed using Argo float data and further adaptations of its parameters are proposed.