Coastal Upwelling Nutrient Pump (2D)

This 2D companion strips coastal upwelling down to its causal chain: alongshore wind stress drives offshore Ekman transport of surface water, mass continuity pulls cold, nitrate-rich deep water up to replace it, and that upward nutrient flux feeds a Monod-limited phytoplankton growth model. Nothing here is set by hand past the wind-speed slider — the upwelling velocity is computed from wind stress through the Ekman-transport balance every frame, then fed into the same advection–diffusion–reaction water-column model as the 3D version. The cross-section panel animates the resulting upwelling circulation cell; the curves panel plots surface nitrate and phytoplankton biomass against simulated time so you can watch a stronger wind visibly raise both.