Seasonal Mixing of the Irminger Sea Water Column

This data nugget highlights the seasonal cycle of seawater temperature and salinity throughout the water column (surface, mid, and deep waters) in the Irminger Sea. During the winter months strong winds and storms mix the water column and similar temperatures and salinities are observed throughout the water column. During the summer months, the winds calm, the water column stratifies, and the surface layers are warmed by the sun leading to temperatures close to 10C while bottom layers remain cold. Surface salinity decrease as winter ice melts. By capturing these annual cycles across decades, scientists can observe variation between years, discover drivers of that variation, and distill long term trends in annual mixing patterns.

These plots represent seawater temperature and salinity data from three CTDs (30, 180, and 1500m depths) on the Global Irminger Flanking Mooring B from Sept 2014 – Aug 2017 (Deployments 1-3).

Credit: OOI Cabled Array program & the Center for Environmental Visualization, University of Washington

Credit: OOI Cabled Array program & the Center for Environmental Visualization, University of Washington

Global Irminger Flanking Mooring B (GI03FLMB)

Location: SW of Greenland in the Irminger Sea
Lat/Lon: 59.7155°N, 39.3148°W
Water Column Depth: 2,800m
Platform: Mooring Riser
Instruments: CTD (CTDMO-G & CTDMO-H) – fixed on inductive wire

Access Data on OOI Net:
30m CTD – GI03FLMB-RIM01-02-CTDMOG060
180m CTD – GI03FLMB-RIM01-02-CTDMOG065
1,500m CTD – GI03FLMB-RIM01-02-CTDMOH071

Click here for Python Code. Code will demonstrate how to download CTD data from multiple instruments on the Flanking Mooring using the Machine-to-Machine (M2M) interface, remove outliers, calculate hourly averages, and export the data as a .csv file.

Download Dataset[link to csv file]

Data Review Pages:
30m CTD
180m CTD
1,500m CTD

OOI Science Theme:

Climate Variability and Ecosystems

Essentials of Oceanography Textbook Sections:

5.2 What important physical properties does water possess?
5.7 How does seawater density vary with depth?
7.3 What causes upwelling and downwelling? Other causes of upwelling

Next Gen Science Standards:

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Related Publications:

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 43:7106–7113,

de Jong, M.F., M. Oltmanns, J. Karstensen, and L. de Steur. 2018. Deep convection in the Irminger Sea observed with a dense mooring array. Oceanography 31(1):50–59,

Palevsky, H.I., and D.P. Nicholson. 2018. The North Atlantic biological pump: Insights from the Ocean Observatories Initiative Irminger Sea Array. Oceanography 31(1):42–49,

Additional Resources: