ASDE - 4DVar
For several years we have been developing a four-dimensional variational assimilation system (Pulido and Thuburn, QJ 2005, 2006) based on the middle atmosphere dynamical model of the University of Reading (Thuburn MWR, 1997; Andrews, PhD Thesis Univ. of Reading, 2001). The model has a hexagonal-icosahedral grid with isentropic levels as the vertical coordinate. The system is also composed by an adjoint model (i.e. a full adjoint of the tangent linear model) and an optimization module based on conjugate gradients.
