EUROFLEETS2 Funded Project "ORCA" Results

Oceanic Response, Controls and Attribution: West Greenland fjord circulation and accelerating glacier discharge

Project Acronym &Title: Oceanic Response, Controls and Attribution (ORCA): West Greenland fjord circulation and accelerating glacier discharge

Area: Uummannaq, West Greenland

Research Vessel: RV Sanna, Greenland Institute of Natural Resources

Chief scientist: Laura de Steur (NIOZ, NL), Jonathan Nash and
Emily Shroyer (OSU, USA), Dave Sutherland (UO, USA)

Date: 5 July 26-August 13, 2014 (carried out jointly with UMQ2014)

Laura de Steur, Royal Netherlands Insitute for Sea Research (NIOZ), The Netherlands

“It was a great opportunity to carry out the ORCA project through EUROFLEETS2. Considering the fact there is limited availability of vessels for Arctic research it was fantastic to be able to use the small but excellent RV Sanna for work in the western Greenland fjords. Results are at present still being analysed however it can be stated that this data set that was collected is unique in a kind. This project will help us to understand the role of the ocean in the discharge of marine terminating glaciers in Greenland which are experiencing rapid change in the last decade.”

Main Objectives

The objective of the programme was to investigate the role of the ocean in controlling the behaviour of two marine-terminating glaciers Rink Isbræ (RI) and Kangerdlugsupp Sermerssua (KS) in central west Greenland. This region is of interest since these two adjacent glaciers terminating in the two fjords show very different behaviour while they reside in a climatological identical region suggesting that the oceanic conditions and forcing may play a role in their different response. The objective was to collect data which allows us to obtain insight in the fjords’ stratification and different water masses, to quantify the heat flux into the fjords and quantify the melt plume from the glaciers…

Work progress and main achievements

The surveys that were carried out as part of ORCA consisted of 8 Conductivity-Temperature-Depth (CTD) and Lowered Acoustic Doppler Current Profiler (LADCP) sections to measure the temperature and salinity distribution and the flow field in the fjords.

In addition, a tracer sampling program was carried out to obtain oxygen isotope data (∂18O) at 8 target depths in the upper 350 m of the water column. These ∂18O data serve as tracers to identify different freshwater source waters. In each fjord 3 or 4 sections were carried out and one CTD section was done outside the double-fjord system to investigate the far-field boundary conditions.

To optimise the research program in this fjords system the ORCA cruise was merged with another planned cruise funded by NASA (UMQ2014) where 5 deep ocean moorings and 2 shallow buoys were recovered, serviced and redeployed and which obtain a continuous time series of temperature, salinity and velocity for a total of two years.

The interpretation of these CTD and ∂18O data together with the year-round observations obtained in the two-year mooring program will provide details of the stratification, heat and freshwater fluxes, and freshwater sources, and ultimately provide improved understanding of the fjords’ circulation in each fjord. The newly obtained insights are crucial for predicting future behavior of outlet glaciers in Greenland where an ocean temperature increase of 1.8°C has been projected.

For more information:

The PharmaDEEP project at laura.de.steur@nioz.nl