# Project : tropics

## Section: Application Domains

### Inverse problems

Inverse problems aim at estimating the value of hidden parameters from other
measurable values, that depend on the hidden parameters through a system of
equations. For example, the hidden parameter might be the shape of the ocean floor,
and the measurable values the altitude and speed of the surface.
Another example is *data assimilation* in weather forecasting.
The initial state of the simulation conditions the quality of the
weather prediction. But this initial state is largely unknown. Only some
measures at arbitrary places and times are available.
The initial state is found by solving a least squares problem
between the measures and a guessed initial state which itself must verify the
equations of meteorology. This rapidly boils down to solving an adjoint problem,
which can be done though AD [44].