Original paper

Ocean Dynamics

, Volume 57, Issue 2, pp 75-89

Spatial and temporal structure of the Denmark Strait Overflow revealed by acoustic observations

  • Andreas MacranderAffiliated withAlfred-Wegener-Institut für Polar- und MeeresforschungIFM-GEOMAR Email author 
  • , Rolf H. KäseAffiliated withIFM-GEOMARInstitut für Meereskunde
  • , Uwe SendAffiliated withScripps Institution of Oceanography, University of California
  • , Héðinn ValdimarssonAffiliated withMarine Research Institute
  • , Steingrímur JónssonAffiliated withUniversity of AkureyriMRI

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Abstract

In spite of the fundamental role the Atlantic Meridional Overturning Circulation (AMOC) plays for global climate stability, no direct current measurement of the Denmark Strait Overflow, which is the densest part of the AMOC, has been available until recently that resolve the cross-stream structure at the sill for long periods. Since 1999, an array of bottom-mounted acoustic instruments measuring current velocity and bottom-to-surface acoustic travel times was deployed at the sill. Here, the optimization of the array configuration based on a numerical overflow model is discussed. The simulation proves that more than 80% of the dense water transport variability is captured by two to three acoustic current profilers (ADCPs). The results are compared with time series from ADCPs and Inverted Echo Sounders deployed from 1999 to 2003, confirming that the dense overflow plume can be reliably measured by bottom-mounted instruments and that the overflow is largely geostrophically balanced at the sill.

Keywords

Denmark Strait Overflow Acoustic observations ADCP PIES Geostrophy