ILRS RSG (Washington D.C. 2002)

Summary of the Refraction Study Group (RSG) - Meeting
Thursday, 10 October 2002 13:30-14:30

Advancing in the topic of atmospheric correction for SLR, the RSG discussed possibilities to test new mapping functions and zenith path delay models. The two-color ranging systems available today are limited to about 1cm accuracy for the remote measurement of the refractive delay. Considering the uncertainty of some millimeters, yielded by a comparison of different refractive delay models, the two-color technique is found to be immature to serve for this test.

It is proposed to perform a mapping function evaluation by means of an analysis of Lageos-2 normal point data spanning from 01.01.1999 to 01.01.2002. The measurement residuals obtained from this analysis should be binned in elevation bins.

This process should be carried out two times:

1. using the Marini atmospheric correction model
2. using the Saastomoinen zenith path delay and the mapping function provided by V. Mendes, as available from the web site

An improvement in the modeling of the atmospheric delay should show up in better residual statistics at low elevations. The following analysts agreed by now to do this: Erricos Pavlis, Cinzia Luceri, Toshimichi Otsubo and Ramesh Govind. The results will be presented at the next analysis working group meeting in Nice 2003.