Diagnosing Overturning and Water Mass Transformation in the Labrador Sea From Argo Floats

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

The sinking of cold, saline water at high latitudes in the Atlantic Ocean and its spread along the sea floor, which is balanced by the return flow of warmer waters at the surface, is known as the Atlantic meridional overturning circulation (AMOC). It plays an important role in maintaining Earth?s climate as well as key ocean properties. Labrador Sea overturning is a key component of AMOC, but its magnitude and variability has been difficult to measure accurately. This study will explore whether float observations can be used as a cost-effective way to answer such questions. The project has the potential to enhance and quantify our understanding of the connection between dense water formation and overturning circulation in the Labrador Sea and lead to an improved strategy for continued AMOC sampling. Information from the study will improve understanding of the spatial and temporal variability of Labrador Sea overturning and export on interannual and decadal timescales. A quality-controlled data set will be available online and incorporated into undergraduate and graduate classes. The project will also support a post doc and facilitate his transition to a more permanent position. The Labrador Sea's contribution to the AMOC is relatively unknown and the potential change between the 1900s and 2000s is still uncertain. The primary objective of the project is to quantify the Labrador Sea?s contribution to the AMOC using profiling floats. The mean overturning calculated in a preliminary analysis is in line with previous estimates, suggesting that floats are a viable dataset for examining these aspects of the Labrador Sea. The project will be part of a large ongoing effort to understand AMOC over the next few years and complement OSNAP moored data. Argo and PALACE floats in the Labrador Sea and boundary current have collected data for the past two decades. The Argo floats offer seasonal and spatial data coverage at the basin-wide scale. PALACE floats data from the 1990s allows the opportunity to compare Labrador Sea overturning from two different periods; one of enhanced deep convection in the 1990s, and weaker convection in the 2000s.