  The dynamics of an ideal wave triad with real amplitudes has a well-known
Nambu representation with energy and enstrophy as conservation laws. Here we
derive Nambu representations for systems with constant forcings. These
equations have been applied to triads of Rossby-Haurwitz waves in the
atmosphere where they are forced with orography. The conservation laws are
based on relations for the unforced amplitudes and a Hamiltonian given by the
total energy plus terms involving the unforced amplitudes. The forcing of the
unstable wavenumber causes a recharge cycle.
