### Abstract

- Top of page
- Abstract
- 1. Introduction
- 2. The “Geometric” Mapping Function
- 3. Davis, Niell, and Herring Mapping Function
- 4. Assessment Setup and Procedure
- 5. Assessment Results
- 6. Summary and Conclusions
- Acknowledgments
- References

[1] The hydrostatic mapping function, *m*(ε), describes the dependence of the hydrostatic path delay on the elevation angle ε. We have developed a simple mapping function, where the only free parameter is an “effective height” of the atmosphere, *H*_{atm}, corresponding to about the first two scale heights above the surface. The value of *m*(ε) is given by the ratio of the straight-line ray path length within height *H*_{atm} to height *H*_{atm} itself. We used simulated delays at GPS (Global Positioning System) frequencies derived from high resolution ECMWF (European Centre for Medium-Range Weather Forecasts) atmospheric analysis fields to assess the performance of the “geometric” mapping function relative to well established ones (the Davis, Niell, and Herring mapping functions, respectively). At elevations >6° the new mapping function generally exhibits, based on a single parameter, a performance comparable to or better than the other mapping functions.