Parametrization (climate modeling)

A typical cumulus cloud has a scale of less than 1 kilometre (0.62 mi), and would require a grid even finer than this to be represented physically by the equations of fluid motion.

More sophisticated schemes add enhancements, recognizing that only some portions of the box might convect and that entrainment and other processes occur.

[2] The formation of large-scale (stratus-type) clouds is more physically based: they form when the relative humidity reaches some prescribed value.

[4] The amount of solar radiation reaching ground level in rugged terrain, or due to variable cloudiness, is parameterized as this process occurs on the molecular scale.

[7] Air quality forecasting attempts to predict when the concentrations of pollutants will attain levels that are hazardous to public health.

[8] Alongside pollutant source and terrain information, these models require data about the state of the fluid flow in the atmosphere to determine its transport and diffusion.

[9] Within air quality models, parameterizations take into account atmospheric emissions from multiple relatively tiny sources (e.g. roads, fields, factories) within specific grid boxes.

Eddies are generated through baroclinic instability, which act to flatten density surfaces through the slantwise exchange of fluid.

However, high-latitude baroclinic eddies are important for many ocean processes such as the Atlantic Meridional Overturning Circulation (AMOC),[14][15] which affects global climate.

[17][18] This parameterisation is not perfect - for instance, it may overpredict the sensitivity of the Antarctic Circumpolar Current and AMOC to the strength of winds over the Southern Ocean.