16 Years of Deep Western Boundary Current measurements in the MOVE array

The MOVE array is one of the longest-running continuous measurements of Deep Western Boundary Current (DWBC) transport and variability, consisting of two end-point moorings deployed in the tropical Atlantic along 16° N, each measuring temperature, salinity, and pressure throughout the water column. In addition, PIES (pressure inverted echo sounders) were deployed alongside each mooring to measure bottom pressure.

Here, we present the newest MOVE transport estimates, expanding our time series of DWBC transports to 16 years, combining bottom-referenced geostrophic transports with pressure fluctuations at the reference level to obtain an absolute measure of transport variability. Bottom pressure measurements obtained from PIES are supplemented by satellite-derived ocean bottom pressure estimates from the GRACE program, using the GRACE data to resolve annual to decadal variability that cannot be inferred from PIES alone due to their limited deployment times and instrument drift. There is good agreement between satellite-derived and in situ bottom pressure data on the 2 to 4 year time scales resolved by both methods, supporting the validity of combining the two datasets.

We further investigate spatial patterns in bottom pressure records from PIES and GRACE data, exploring the existence of coherent basin-wide modes and their possible impact on ocean circulation. Finally, we compare our measurements of transports and bottom pressure at 16° N to various other measures of AMOC variability in the North Atlantic, including data from different moorings as well as modeling data, studying the differences and similarities in various AMOC variability estimates to help further our understanding of the causes and implications of the observed trends.