Primary objective of the UNDER-ICE project is to advance the knowledge about water masses and processes in ice-covered seas, including heat and volume fluxes, freshwater fluxes, ice-ocean processes and primary production based on observations and modelling in the European sector of the Arctic Ocean. This new knowledge is needed to understand the mechanisms causing the reduction of the sea ice and the role of the Arctic Ocean in the climate system.

The central component of UNDER-ICE is the acoustic network for acoustic tomography, oceanography and passive acoustics in the Fram Strait. The five UNDER-ICE moorings were deployed in September 2014, and successfully recovered in the period 27 June till 27 July 2016 with KV Svalbard. Following the recovery cruise we have carried out pre-processing of data from UNDER-ICE acoustic and oceanographic moorings using the new meta-data format for the acoustic data. Currently, more detailed processing and analysis is going on using recordings from the vertical acoustic arrays comprised by 10 hydrophones and oceanographic data (WP1). A strong focus is on developing the set up for constraining ice-ocean models using the acoustic measurements (WP1/3). Different ice-ocean models are under validation with respect to heat transports through Fram Strait (WP3).

The main experiment components are overlais the Sentinel image from 7 July 2016. The red pentagons are the five acoustic moorings recovered in 2016. The two sources are positioned in UI-2 and UI-5, the others were carrying the stand alone receiver arrays of 10 hydrophone modules. The yellow, blue and red lines show the drift of three GPS instruments placed on selected ice floes in vicinity of the UI-4. The green and the pink lines show the track of two sailbuoys used to obtain oceanographic surface measurements. (Fig by Mohamed Babiker, 2016)