Spherical Spline Application to Radio Occultation Data

Abstract

Spherical Spline Application to Radio Occultation DataIn recent years, the importance of the Radio Occultation Method (ROM), an observation procedure of atmospheric quantities such as temperature, density, pressure, and water vapor, increased in value. Based on the global distribution and the high accuracy of the measurements between the Earth's surface up to 35km altitude, ROM offers new perspectives for climate monitoring. In order to compare the measurements, the data have to be visualized. This paper gives the basic definitions and theorems of spline approximation on the sphere. Via its adjustable smoothing parameters, ROM can be suitably adapted to approximate the given data. Further on, it demonstrates, splines as approximation structures realizing a minimal bending energy of their graphs provide a good approximation of the data at hand. Our results demonstrate that spherical spline approximation is an appropriate method to visualize the change over time of a given layer and to illustrate the vertical composition of the Earth's atmosphere. Moreover, ROM enables us to compare the layers of the atmosphere at different points in time as well as the approximation of parameters between the measurements on arbitrary points on the Earth.