Research on the implementation of GPS radio occultation one-dimensional bending angle operator in four-dimensional variational data assimilation system

Abstract

GPS radio occultation data are implemented in the numerical weather prediction as a kind of very important observation data because of its excellent characteristics, which makes a remarkable positive effect in the system. In this article, we design an implement method and a quality control strategy of one-dimensional bending angle operator in four-dimensional variational data assimilation system, and we also describe the steps of implementing one-dimensional bending angle forward operator and its linear and adjoint operators in four-dimensional variational data assimilation system. The author chose Reger’s three term expression and its best average coefficients are chosen to calculate refractivity values. In this article, we introduce an observation error model of one-dimensional bending angle operator through the statistics of GPS radio occultation observation data of August, 2012. A comparison of experiment of the analysis field between in the cases with and without GPS radio occultation data is made. It is concluded that GPS radio occultation data plays a positive role in the global areas, especially in the low and middle latitude areas higher than 10 km. This conclusion is the foundation of the following-up GPS radio occultation data assimilation verification experiments.