This manual gave a description how to use the WamC5 system, which allows for adjoint runs of the WAM model.
The forward model takes as input a set of control variables.
On the basis of their values, the WAM model is integrated.
As output a cost is returned which, for instance reflects the agreement between model results and data.
The adjoint model calculates the gradient of the cost with respect to the control variables.
As input it sets the adjoint variable corresponding to the cost to one and the remaining ones to zero, as output it returns the adjoint variables of the control variables, which are equivalent to the gradient.
The adjoint model was constructed automatically from the WAM source code, by the use of the Adjoint Model Compiler.
H Hersbach. The adjoint of the WAM model
KNMI number: WR-97-01, Year: 1997, Pages: 33