Horizontal Stratification during Deep Convection in the Labrador Sea

摘要

Deep convection-the process by which surface waters are mixed down to 1000 m or deeper-forms the primary downwelling of the meridional overturning circulation in the Northern Hemisphere. High-resolution hydrographic measurements from Seagliders indicate that during deep convection-though water is well mixed vertically-there is substantial horizontal variation in density over short distances (tens of kilometers). This horizontal density variability present in winter (January-February) contains sufficient buoyancy to re-stratify the convecting region to observed levels 2.5 months later, as estimated from Argo floating platforms. These results highlight the importance of small-scale heterogeneities in the ocean that are typically poorly represented in climate models, potentially contributing to the difficulty climate models have in representing deep convection.