 \,\frac{h'}{h} \left(  \eta' - \eta \,\frac{h'}{h} + \nabla_y \eta \cdot R y (\tau + \alpha') - \nabla_y \eta \cdot y \,\frac{h'}{h} \right) \,ds dy\, , \\ m_\varepsilon^0(wu_0, \eta) & : = & \int_{\mathbb R \times S} w \nabla_y u_0 \cdot 