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 http://www.jcet.umbc.edu/~epavlis/PORTO_MODEL.txt.

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.