KINEMATIC GPS AS A SOURCE FOR AIRBORNE GRAVITY REDUCTION IN THE AIRBORNE GRAVITY SURVEY OF SWITZERLAND

An airborne gravity survey of Switzerland was performed in a joint pro ject between the Swiss Federal Institute of Technology, Zurich and LaC oste and Romberg Gravity Meters, Inc. The survey was flown in a Twin-O tter aircraft equipped by the Swiss Federal Directorate of Cadastral S urveying; The aircraft was outfitted with three Global Positioning Sys tem receivers, one for navigational purpose and two as Sources of posi tioning, velocity, and vertical acceleration for airborne gravity redu ction. Four receivers were installed on the ground as reference statio ns. The gravity data were recorded with a modified LaCoste and Romberg marine gravimeter at a sampling rate of 1 s. Modifications included a nti-alias filters and an absolute encoder for the measuring screw. The flights were performed at a barometric altitude of 5100 m above sea l evel. An airborne Bouguer anomaly map, computed at flight altitude wit h topographic corrections of up to 167 km and a density of 2670 kg/m(3 ), is presented. Bouguer anomaly values at crossing points between lin es flown at comparable altitudes (Delta H < 10 m) show differences var ying between 1.1 and 2.7 mGal (10(-5) m/s(2)). Comparison of the groun d Bouguer anomaly map, upward continued to 5100 m, and the one compute d from airborne data shows a strong similarity both in amplitude and w avelength.