Ocean_current - Wikiparency

# Ocean current Ocean currents are the persistent horizontal flows that carry water — and with it heat, salt, nutrients and anything drifting — around the globe. [[Ekman_transport|Wind]] drives the surface layers; [[Density]] differences drive the deep. Rotation shapes both, which is why the great surface gyres turn clockwise in the northern hemisphere and anticlockwise in the southern. ## Microsim — p5.js Sidecar: `Ocean_current.p5.js` · route leaf: `microsim/p5js/Ocean_current__20260910T0400Z`. Built to the Betterfire Standard v0 (single `ARTICLE` constant, HUD title and Wikitube URL, control hints, parameter readout and equation). | Control | Does | |---------|------| | `wind slider` | strength of the wind forcing | | `beta slider` | how fast Coriolis varies with latitude | | `[t]` | show or hide drifter trails | *What to watch:* Turn off the latitude variation in Coriolis and the gyre goes symmetric — the western boundary current vanishes. Turn it back on and the flow crowds against the western wall. ## Why the western sides are fast Every ocean gyre is lopsided. The current on its western edge — the Gulf Stream, the Kuroshio — is narrow, deep and fast, while the return flow across the rest of the basin is broad and sluggish. The cause is that the [[Coriolis_force|Coriolis]] parameter varies with latitude, so [[Vorticity]] balance cannot be satisfied symmetrically; Henry Stommel showed in 1948 that removing that variation makes the gyre symmetric and unreal. It is one of the cleanest demonstrations anywhere that a small gradient in a [[Dimensionless_quantity|parameter]] can reorganise an entire flow field. ## What they carry Currents move roughly as much heat poleward as the [[Atmosphere_of_Earth|atmosphere]] does, which is why western Europe is mild at the latitude of Labrador. They set where nutrients surface and therefore where fisheries are, distribute larvae and pollution, and shaped every sailing route ever planned — a [[Turbulence|mixing]] system and a transport system at once. Satellite altimetry now maps them continuously through [[Geostrophic_current|geostrophy]], and the deep limbs through [[Thermohaline_circulation]]. **Reads with:** *Introduction to Physical Oceanography (Robert H. Stewart, 2008)* — [OTL record](https://open.umn.edu/opentextbooks/textbooks/introduction-to-physical-oceanography) · [download](https://github.com/introocean/introocean-en/releases/tag/v20200229) · CC BY-NC-SA. Section 7 of the [[PORTAL_Thury_Hydrodynamics_Apex_Spine|Apex Spine]] book shelf. **On the spine:** [[Geostrophic_current]] · [[Ekman_transport]] · [[Thermohaline_circulation]] · [[Vorticity]] · [[WT!Thury_Hydrodynamics_Compendium]].  *Linked from the [[WT!Thury_Hydrodynamics_Compendium|Thury Hydrodynamics Compendium]], section 18, Geophysical fluid dynamics.*   **Microsim — three.js (Wikitube framework):** *Ocean current* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/thury/Ocean_current.html" data-title="Ocean current"></div> *Built from `MICROSIM_GUIDE/specs/variants/Ocean_current.json`; part of the [[WT!Thury_Hydrodynamics_Compendium|Thury Hydrodynamics Compendium]] set.*  ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Ocean_current) : [Wikitube](https://en.wikitube.io/wiki/Ocean_current) ## Previous hub tags Hubs: `Life_Physics`, `Systems`. Portals: [[PORTAL_Thury_Hydrodynamics_Apex_Spine]], [[PORTAL_WT!Thury_Hydrodynamics_Compendium]], [[PORTAL_Physics]]. --- *Book-section wave · 2026-09-10 · article + p5 microsim shipped together.*