Seawater API
Seawater oceanography maths as an API, computed locally and deterministically from the standard equations — the density, freezing-point and chlorinity numbers an oceanographer, marine scientist or aquarist works with. The density endpoint gives the seawater density and σt from salinity and temperature using the full UNESCO EOS-80 one-atmosphere equation of state — it reproduces the official check value of 1027.675 kg/m³ at 35 PSU and 5 °C exactly — around 1,025 kg/m³, rising with salinity and falling with temperature, the two drivers of the ocean's density-driven circulation where cold salty water sinks. The freezing-point endpoint gives the freezing point from salinity (Millero): about −1.9 °C at the ocean's typical 35 ppt, and because salt also pushes the temperature of maximum density below freezing, seawater keeps overturning and cooling all the way down instead of stratifying like a freshwater lake — why the open ocean rarely freezes outside the polar seas. The chlorinity endpoint converts between salinity and chlorinity through the Knudsen relation S = 1.80655 × Cl, the classic titration measure that the constant major-ion proportions of seawater make reliable. Everything is computed locally and deterministically, so it is instant and private. Ideal for oceanography and marine-science tools, ocean-model and sensor pipelines, aquarium and aquaculture apps, and environmental dashboards. Pure local computation — no key, no third-party service, instant. Surface (atmospheric-pressure) forms. 3 compute endpoints. For the speed of sound in seawater use a sonar API; for general colligative properties a colligative-properties API.
api.oanor.com/seawater-api
