Arctic Sea ice has been shrinking over many decades, indicating that there is more heat available in the climate system. Future prediction of this development, which is also important for socio-economic aspects like shipping or exploitation of resources, requires better understanding of the relevant processes. Although heat transport to the Arctic through the ocean circulation has been assumed to play an important role on the Arctic Ocean sea ice reduction, we do not know how much oceanic heat has been carried to the Arctic over last decades. By using observations for quantification of this heat transport for the first time, ARCGATE provides important information to assess Arctic change.
The export of fresh water (FW) from the Arctic Ocean to North Atlantic is another important process in the climate system. It has the potential to modulate the Atlantic Meridional Overturning Circulation, and consequently affect European climate. Almost all climate models predict that the Arctic is one of the most vulnerable regions in the world for future climate change. However, we do not know enough about the role of these processes in the present day climate to be able to predict with confidence what the future will look like.
The main Arctic gateways are Davis Strait, Fram Strait, Bering Strait and Barents Sea Opening (BSO). Velocity, temperature and salinity have been observed by six research groups in USA, Germany and Norway over the last decades to monitor the exchanges of mass, heat, FW between the Arctic Ocean and surrounding oceans. (Figure 1). However, no attempts were made to integrate fluxes over all mooring arrays across the Arctic boundary to draw a comprehensive picture of the Arctic heat and FW budget. In this project, data of all mooring arrays were integrated in order to quantify time variability of ocean circulation and associated heat and FW transports between 2004 and 2010 (Figure 2).
To do so, data of around 1,000 individual moored instruments in the Arctic main gateways from six different research groups were assembled. The obtained time series provide a benchmark data set for the validation of numerical general circulation models of the Arctic Ocean and air-sea surface heat and FW fluxes estimates from atmospheric re-analyses products.
