Mixed layer depth climatology over the northeast U.S. continental shelf (1993–2018)

The Northeast U.S. (NEUS) continental shelf has experienced rapid warming in recent decades. Over the NEUS shelf, circulation and annual cycle of heating cooling lead to local variability water properties. mixed layer depth (MLD) is a key factor that determines amount upper ocean warming. A detailed description MLD, particularly its seasonal spatial patterns, not been developed for shelf. We compute MLD using an observational dataset from Fisheries Science Center hydrographic monitoring program. exhibits clear cycles across five eco-regions on with maxima January–March minima July or August. largest western Gulf Maine (71.9 ± 24.4 m), smallest southern Mid-Atlantic Bight (34.0 7.3 m). Spatial variations are seasonally dependent, greatest homogeneity summer. Interannual dominates long-term linear trends most regions seasons. To evaluate sensitivity our results, we compare MLDs calculated 0.03 kg/m3 density threshold those 0.2 °C temperature threshold. Temperature-based generally consistent density-based MLDs, although small number temperature-based biased deep compared spring fall. Finally, high-resolution reanalysis GLORYS12V1. While mean values GLORYS12V1 well observed their interannual highly correlated, These results can be starting point future studies drivers temporal