The Long-term Ocean Circulation Observations (LOCO) project was a project funded by the Netherlands Science Organisation (NWO). The original LOCO project that started in 2003 consisted of several moored observation locations, in the central Irminger Sea (Figure 1), over the Mid Atlantic Ridge, in the Mozambique channel and in a branch of the Indonesian throughflow. Of these locations two remain today, the central Irminger Sea and the Mozambique channel.
The Irminger Sea data consists of a time series from 2003 to 2008 from LOCO 3 on the eastern side of the basin and a time series from 2003 to present from LOCO 2 on the western side of the basin and close to the center of the Irminger gyre. Both moorings are/were outfitted with two downlooking Acoustic Doppler Current Profilers (ADCP), one at ~150 m and one at ~2400 m. In between these ADCPs runs a McLane moored profiler, which records daily CTD profiles (Figure 2). A seperate CTD sensor is placed near the anchor of the mooring.
The time series of LOCO 2 and 3 (Figure 3) reveal the seasonal changes in stratification caused by surface buoyancy fluxes and lateral advection of warmer boundary current water. On shorter time scales the data shows influence of meso scale eddies. These warm core eddies are likely play an important role in the restratification.
The first deep mixed layers (1000 m) were observed at LOCO 3 in the winter of 2007-2008 (de Jong et al., 2012). However, much deeper mixed layers (1400 m) were observed at LOCO 2 in the recent winter of 2014-2015 (Figure 4 and published in de Jong & de Steur, 2016). These mixed layers completely removed the signature of the layer of Labrador Sea Water in the Irminger Sea and replaced it with locally ventilated waters. These new observations highlight the need to consider the Labrador and Irminger Seas as one convective system rather then looking only at the Labrador Sea.
The LOCO 2 mooring is currently funded by the European NACLIM program and has been redeployed for a two-year deployment in the summer of 2016.
Data from the LOCO mooring is available from OceanSITES. Please keep me updated on publications using LOCO data.
Publications using LOCO data
de Jong, M. F. and L. de Steur (2016). Strong winter cooling over the Irminger Sea in winter 2014-2015, exceptional deep convection, and the emergence of anomalously low SST. Geophysical Research Letters, 42, doi: 10.1002/2016GL069596.
Paquin, J.-P., Lu, Y., Higginson, S., Dupont, F., and G. Garric (2016). Modelled Variations of Deep Convection in the Irminger Sea during 2003–10. Journal of Physical Oceanography, 46, 179-196, doi: 10.1175/JPO-D-15-0078.1.
de Jong, M. F., van Aken, H. M., Våge, K., and R. S. Pickart (2012). Convective mixing in the central Irminger Sea: 2002-2010. Deep-Sea Research I, 63, 36-51.
Jonkers, L., Brummer, G.-J. A., Peeters, F. J. C., van Aken, H. M., and M. F. de Jong (2010). Seasonal stratification, shell fluxes and oxygen isotope dynamics of left coiling N. pachyderma and T. quinqueloba in the western sub-polar North Atlantic. Paleoceanography, 25, PA2204.
Booij, K., van Bommel, R., van Aken, H.M., van Haren, H., Brummer, G.-J.A., and H. Ridderinkhof (2014). Passive sampling of nonpolar contaminants at three deep-ocean sites. Environmental Pollution, 195, 101-108.