Nudging
From Glossary of Meteorology
nudging
A four-dimensional data assimilation method that uses dynamical relaxation to adjust toward observations (observation nudging) or toward an analysis (analysis nudging).
Nudging is accomplished through the inclusion of a forcing term in the model dynamics, with a tunable coefficient that represents the relaxation time scale. Computationally inexpensive, nudging is based on heuristic and physical considerations.
