Eddy‐Resolving In Situ Ocean Climatologies of Temperature and Salinity in the Northwest Atlantic Ocean

Abstract Circulation patterns and thermohaline fields of the Northwest Atlantic are highly variable in space and time and are strongly impacted by various mesoscale phenomena such as quasi‐stationary frontal zones with sharp gradients, meandering jet‐like currents, vortexes, and filaments. These all contribute to building and maintaining complex large‐scale regional structures of ocean tracers, such as temperature and salinity, which persist over time periods of decades and longer. To reflect the existence of these long‐term mesoscale phenomena and diagnose their changes, a new high‐resolution in situ climatology of the Northwest Atlantic was developed. At its core, this eddy‐resolving climatology, with 1/10° horizontal resolution, reveals a cumulative effect of mesoscale dynamics within the Northwest Atlantic. Additionally, strong agreement exists between this in situ climatology and climatologies derived from high‐resolution satellite data, thus providing a validation of the presence of stochastic periodicity of ocean tracer patterns on decadal timescales. Furthermore, large and very localized multidecadal subsurface heat gains southeast of the Gulf Stream was diagnosed using this new high‐resolution regional climatology. It was demonstrated that the climatic shifts in the wind stress over the Northwest Atlantic may play a leading role in this heat accumulation due to subtropical water heaving through Ekman pumping. It is argued that uncovering many important details of long‐term ocean climate variability from in situ ocean data can only be ascertained through the use of eddy‐resolving climatologies.