Atmospheric Refraction at Optical Wavelengths: Problems and Solutions

Atmospheric refraction is an important accuracy-limiting factor in the application of satellite laser ranging (SLR) to high-accuracy applications. The modeling of that source of error in the analysis of SLR data comprises the determination of the delay in the zenith direction and subsequent projection to a given elevation angle, using a mapping function. Standard data analyses practices use the Marini-Murray model for both zenith delay determination and mapping. This model was tailored for a particular wavelength and is not suitable for all the wavelengths used in modern SLR systems. Using ray tracing through a large database of radiosonde data, we assess the zenith delay models and mapping functions currently available and the sensitivity of models and functions to changes in the wavelength and we give some recommendations towards a unification of practices and procedures in SLR data analysis. 1