Periodic Reporting for period 1 - ARCGATE (ARCGATE: maximizing the potential of Arctic Ocean Gateway array)
Reporting period: 2015-07-01 to 2017-06-30
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.
In collaboration with a research group at University of Vienna, 1-year volume and heat transport data were exploited to validate the state-of-art ocean data assimilation product. We found that the data assimilation product reproduces the horizontal ocean circulation reasonably well, in term of mean value and its variability. However, we also found that modelled ocean circulation in Davis Strait and BSO were both stronger than observations by ~30%.
The main outcome of the project was the 6 years of ocean transport of volume, heat and FW transport. The 1-year data (during September 2005 to August 2006) was already deposited in PANGAEA, and the entire 6 years data will be deposited when corresponding scientific paper will be submitted to a peer review journal by end of 2017.