An Improved One-Dimensional Bending Angle Forward Operator for the Assimilation of Radio Occultation Profiles in the Lower Troposphere

Abstract Under very large vertical gradients of atmospheric refractivity, which are typical at the height planetary boundary layer, assimilation radio occultation (RO) observations into numerical weather prediction (NWP) models presents several serious challenges. In such conditions, RO bending angle profiles is an ill-posed problem, uncertainty associated with higher, and one-dimensional forward operator used to assimilate these has theoretical deficiencies. As a result, larger percentage rejected NWP centers by existing quality control procedures, potentially limiting benefits this data type improve forecasting in lower troposphere. To address problems, new methodology that enables be extended moist troposphere been developed. Challenges refractivity partially overcome reformulation minimal effect higher altitudes. first step toward effort, study both development forecast impact assessment it using NCEP system. Though conservative approach, tropical already noticeable. The encouraging results work open potential for further exploitation optimization assimilation.