Ocean mixed layer dynamics: high-resolution simulations of wind, wave and convective effects

• Main Author: Agnieszka Herman
• Format: Dataset
• Language: English
• Published: Gdańsk University of Technology 2020
• Subjects: hydrodynamic model; ocean mixed layer; Ekman circulation; ocean convection; CROCO; sea ice formation; polynya; Antarctic; Arctic; Antarc*; Sea ice
• Online Access: https://dx.doi.org/10.34808/8b4t-qb16; https://mostwiedzy.pl/en/open-research-data/ocean-mixed-layer-dynamics-high-resolution-simulations-of-wind-wave-and-convective-effects,12301226501250492-0

This dataset contains results of high-resolution numerical simulations of the ocean mixed layer (OML) forced by wind, waves and cooling from the atmosphere, i.e., under strongly turbulent, convective conditions. The goal is to provide detailed, three-dimensional information about OML circulation, turbulent kinetic energy, and temperature and salinity variations under conditions that are typical e.g. for Arctic and Antarctic polynyas. Understanding those water bodies is crucial for both regional and global ocean and climate models, and the description of OML dynamics there is a prerequisite for developing models of sea ice formation and ocean convection under strongly turbulent conditions. The simulations were performed with a state-of-the-art, open-source hydrodynamic model CROCO (http://www.croco-ocean.org/), modified and configured to make it suitable for the present study. The model domain covers surface area of 1200m*1200m (with horizontal resolution of 3m and periodic lateral boundaries) and is 150m thick (with 60 vertical levels of variable thickness, ranging from 9m at the bottom to 0.5m at the top. A nonhydrostatic, non-Boussinesq version of the model is used (permitting high vertical velocities related to convective plumes), with wave-induced currents (Stokes drift), forced by heat and momentum fluxes from the atmosphere. The model correctly reproduces the Ekman circulation in the OML The model is run for a range of wind speeds (from 5 to 30 m/s) and air-water temperature differences (from -20 to 0degrC). Deep water wind waves are assumed (i.e., no presence of swell), with parameters (significant wave height, peak period) computed from the wind speed. The mixed layer depth equals 100m, a value which is representative for many polar polynyas. Each individual simulation is initialized with a horizontally uniform, analytical Ekman-Stokes solution corresponding to a given wind/waves forcing, and continued for 18 hours. The results are saved every 1 hour in the form of: Area-averaged values of surface heat and momentum fluxes Area-averaged vertical profiles of the current velocity components, turbulent kinetic energy, water temperature, salinity and density (and their standard deviation) Three-dimensional fields of the variables listed above at two selected time instances, 12 and 18 hours after initialization.