Global seasonal climatology of barrier layer thickness (BLT), barrier layer insulation (BLI), and derived variables

A global seasonal climatology of barrier layer properties, including barrier layer thickness (BLT), barrier layer insulation (BLI), and derived energetic variables, is provided. This climatology is based on an energy-based framework that quantifies the insulation effect of barrier layers in terms of the resistance they impose to the entrainment of cold thermocline water into the mixed layer. In this context, BLI represents the buoyancy potential energy required for a water parcel at the base of the barrier layer to reach the mixed layer, providing a physically consistent measure of the barrier layer’s ability to inhibit vertical exchange and cold entrainment. This approach extends the traditional geometric characterization based on BLT by incorporating the vertical density structure and its associated energetics, thereby offering a more comprehensive description of upper- ocean stratification. The dataset contains global seasonal climatologies computed over standard three-month periods: January–March (JFM), April–June (AMJ), July–September (JAS), and October–December (OND). The climatologies are derived from approximately 2.8 million in situ Argo profiles spanning the period from 2005 to 2024. Only delayed-mode profiles with quality flags indicating good and probably good data (flags 1 and 2) were considered. Observations were aggregated onto regular spatial grids at two resolutions (1° × 1° and 2° × 2°). Within each grid cell and season, only profiles with BLT ≥ 5 m were considered to define the presence of a barrier layer. The variables were computed for each profile and subsequently averaged to obtain representative seasonal values for each grid cell. The files contain the following variables: - latitude: Latitude of the grid cell (degrees north). - longitude: Longitude of the grid cell (degrees east). - season: Climatological season. - blt: Barrier layer thickness (m), defined as the difference between the isothermal layer depth (ILD) and the mixed layer depth (MLD). - bli: Barrier layer insulation (J kg⁻¹), defined as the buoyancy potential energy required to displace a water parcel from the ILD to the MLD. - bli_dens_rate: BLI density rate (J kg⁻¹ m⁻¹), defined as the ratio between BLI and BLT, representing the insulation per unit thickness. - n_bl: Number of profiles within each grid cell and season with BLT ≥ 5 m. - n_profiles: Total number of profiles within each grid cell and season. - bl_proportion: Fraction of profiles with BLT ≥ 5 m, representing the occurrence of barrier layers.