KAIRAKU

Ten interactive ocean simulators: conveyor, Ekman spiral, tides, vents, food webs, blooms, waves, coral, sea ice. From high-school earth science to oceanography.

KAIRAKU is a visual-first oceanography education app. It is the 18th title in the "RAKU" series following SUUGAKU, BUTURAKU, DENRAKU, HAMON, NETURAKU, SEIRAKU, KORAKU, RYORAKU, RYURAKU, KAKURAKU, KIKARAKU, KAGAKU, KINRAKU, NOURAKU, KIRAKU, CHIRAKU and IRAKU. The theme this time is the ocean — its currents, its deep, its life and its ice.

— Ten Interactive Simulators —

OCEAN CONVEYOR (Thermohaline Circulation) Warm surface water flows poleward, is cooled and densified at high latitudes, then sinks and returns through the deep over ~1500–2000 years. Particle animation shows the global belt; sliders for equator-pole temperature difference, salinity, and flow speed change the sinking strength.

EKMAN SPIRAL The wind drags the surface; Coriolis turns each successive layer to the right (Northern Hemisphere) while damping its speed exponentially. Adjust wind, latitude and observation depth to see the spiral and the depth-integrated Ekman transport at 90° to the wind.

VERTICAL PROFILE T, S and density (σθ) versus depth for polar, temperate and tropical oceans in winter or summer. The mixed layer, main thermocline and pycnocline are visible in a single view.

HYDROTHERMAL VENT A 350–400°C black smoker on the mid-ocean ridge. Adjust vent temperature and flow rate; the biome extent (tube-worm community) is derived automatically from the chemosynthetic activity, peaking near 300°C with strong flow.

MARINE FOOD WEB Phytoplankton, zooplankton, small fish, large fish and an apex predator on log-scale boxes. Sliders for primary production and predation pressure recalculate the trophic biomass — the ~10% ecological efficiency made visible.

SPRING BLOOM A simple NPZ-style model. Push light, nitrate, and grazing and watch phytoplankton biomass rise, peak and crash on a real-time time-series.

TIDES Two tidal bulges on a rotating Earth, an orbiting Moon and a fixed Sun. Move the lunar phase to see spring tides at new/full moon and neap tides at the quarter phases; move the hour slider to track the observer's tide level.

WAVE REFRACTION & BREAKING Set offshore wavelength, height and sea-floor slope. The simulator computes shoaling (shortening wavelength, growing height) and marks the breaking line at H/h ~ 0.78.

CORAL BLEACHING Sea-surface temperature, pH and the number of days above threshold feed a Degree-Heating-Weeks model that flips the colony from healthy to bleached to dead. See the joint effect of warming and ocean acidification.

SEA ICE Polar ocean cross-section driven by air temperature, sunlight and wind. Watch ice grow below -1.8°C and reject brine that sinks beneath as the trigger for deep-water formation; watch melting expose darker water that absorbs more heat (ice-albedo feedback). Polar night brings aurora and stars; the midnight sun rides high during polar day — the full annual cycle in a single view.

— Features —

• Built-in explainer sheet on every screen
• Real-time computation of textbook ocean equations
• Japanese / English
• Light and dark themes
• Polished, intuitive UI

— Good for —

• High-school earth-science and intro oceanography students
• Anyone who wants to understand ocean currents, the deep sea and marine ecosystems intuitively
• Teachers looking for visual classroom material
• Readers of climate, coral and plastic-pollution news who want the fundamentals