This simulator contrasts a wind-driven surface stream with a conceptual density-driven overturning loop in a basin cross-section. Change the polar reservoir temperature and salinity and the signed wind forcing, and watch the density contrast and overturning index respond.
• A real-time 3D scene with 5 inspectable parts (Wind-driven surface stream, Polar cooling and sinking zone, Deep return pathway, Warm low-latitude reservoir and Basin cross-section), with home view, focus-selected-part, auto-rotate, expand, instrument-cover and hide-labels scene tools, plus a model response curve beneath the scene. • Experiment controls: Polar reservoir temperature (0-20 °C); Polar salinity (30-38 g/kg); Signed surface wind forcing (-2-2 visual units); show explanatory motion markers; pause/resume, 0.1 s and 1 s single-step buttons, four playback speeds and a restart button. • A Curves & measurements tab with a parameter-comparison chart, a live-measurements chart, the model equations and snapshot readouts (Warm reservoir density; Polar reservoir density; Polar minus warm density; Signed overturning index; Surface wind index). • An Experiments tab with 2 guided presets (freshwater dilution and cold saline water) and a Model verification bench that runs independent fresh models, plus a timestamped event log and a copyable trial report. • A Learn & assess tab with guided lessons, a knowledge-check quiz with reset and a written model-scope statement linking to a technical reference.
Seawater density is linearized as rho = 1027 [1 - alpha (T - 10) + beta (S - 35)] kg per cubic meter, with alpha = 2 x 10^-4 per kelvin and beta = 7.6 x 10^-4 per g/kg. Colder or saltier water is denser. The lab reports warm and polar reservoir densities, their difference, and a signed overturning index equal to that difference divided by 5 and clipped to plus or minus 2.
Freshwater dilution lowers polar density and weakens sinking, while cold saline water strengthens it.
Surface wind sets the wind index and drives the upper stream, but density differences also contribute to ocean circulation within broader ocean dynamics. More dissolved salt raises density at fixed temperature.
The model is linearized with prescribed transport paths, not seawater thermodynamics or an ocean prediction. The overturning index is dimensionless and illustrative, and Coriolis effects, mixing energy, pressure effects and real basin boundaries are excluded.
Yes. At a fixed temperature, more dissolved salt generally raises density. The polar salinity slider in the lab changes the polar reservoir density and so the overturning strength.
No. Wind drives the surface stream, but density differences from temperature and salinity also drive overturning circulation, as the two parts of the scene show.
A dimensionless illustrative number equal to the polar minus warm density difference divided by 5, clipped between -2 and 2. Positive values mean the polar water is denser and sinking.
No. It is a linearized density model with prescribed paths. It excludes Coriolis effects, mixing, pressure effects and real basin shapes.