Airborne scalar gravimetry for regional gravity field mapping and determination

Abstract

Airborne gravity is capable of providing an accurate and bias-free extension of satellite gravity models and thus bridges the spectral gap between these models and the fine structure of the gravity field as mapped by the newest digital elevation models (SRTM). Airborne gravity is therefore an ideal base for regional gravity/geoid modeling. Airborne gravity may also be an efficient tool to validate existing datasets e.g. older marine surveys and is the only efficient way to cover the near coastal zone where altimetry derived gravity fails to deliver reliable data. This paper describes some recent surveys undertaken by Danish National Space Center (DNSC) including both surveys over marine areas in the Arctic and the North Atlantic region and surveys over land covering all of Malaysia and Mongolia. The purpose has been to contribute to regional and global models (ArcGP and EGM2006), to provide geoid models for national height systems and reference surfaces for ocean current studies. The measurements were done with a LaCoste & Romberg marine/airborne gravimeter owned by the University of Bergen. This type of gravimeter has an excellent drift characteristic and can when the data are properly processed provide bias-free results also for airborne applications. The main source for a bias in airborne data obtained with stabilized platform systems is the socalled tilt correction, which basically is a modeling of the platform orientation error. A new platformresponse- modeling approach to account for this effect will be described. This approach seems to give virtual bias-free results.