# Semigeostrophic theory

From AMS Glossary

## semigeostrophic theory

A more accurate alternative to quasigeostrophic theory that involves the geostrophic momentum approximation to the quasi-static primitive equations.

In semigeostrophic theory the full effects of ageostrophic advection are included. Atmospheric structures such as fronts, small strong low pressure cells, and broad weak high pressure cells are more accurately represented in semigeostrophic theory than in quasigeostrophic theory.