Terms of Reference and Objectives

Within the next four years, the SSG on Aerogravimetry and Gradiometry should concentrate on three major items.

- Now that CHAMP and GRACE are operative and first independent, single satellite models are available for the gravity community, and with the GOCE mission on the horizon, aerogravity campaigns should be designed to close the gap between near-surface measurements (land-based, ship-borne) and satellite observations. Taking the GRACE mission as an example, the design of future aerogravimetry surveys should make sure that long wavelengths (minimum of 250 km profile length) are resolved with stable, best possible accuracy with a resolution that fits to medium wavelength features measured on ground (some ten to hundred km). A new generation of scientific survey aircraft available in the next years such as the planned HIAPER aircraft (USA) and HALO aircraft (Germany) that are mainly designed and planned to be used for atmospheric sciences should also be adopted for large scale aerogravimetric surveys. The aircraft will be of the type of Bombardier Express or Gulfstream V which both are capable to fly distances up to 10000 km. Such type of aircraft allows to fly gravimetry in a sub-continental to continental range. The gravimetry community should soon develop surveys for these aircraft as they will be available in 2006/2007.

- In the meanwhile, large unmapped areas as the Amazon Basin and Antarctica should be covered by systematic aerogravimetry surveys. For the Amazon Basin, a Brazilian scientific and commercial community has already claimed a large interest to cover the northern Amazon Basin. As for Antarctica, a special logistic and long standing experience is needed to cover the continent with aerogravimetric surveys. The institutions involved as BAS, AWI, USGS, etc. already have special science plans developed. IAG should give these institutions some official back-up and help in long term coordination of Antarctic aerogravimetry activities.

- The fast development of gradiometer systems for airborne gravimetry opens a complete new spectrum of accuracy and resolution in local to regional surveys. For the scientific community two problems arise to utilize the new instruments for their aims: most developments are purely made on a commercial base and gradiometer systems often operate only on a specially designed aircraft, so the system cannot be swapped between aircraft. Here, a new link between industry and science has to be accomplished. The working group members should enforce the use of gradiometer systems on local targets of special interest. One mid-term aim should be the installation of a gradiometer system on HIAPER or HALO in order to fly on GOCE orbits with as much time synchronization as possible also using laser or radar systems for sea surface measurements over the Atlantic.

- The use of the latest satellite gravity observations encouraged the development of new techniques to process traces of satellite data. Some of the new, emerging ideas might be as well very useful in aerogravimetry data processing. Therefore, a set of aerogravity data from different systems should be made available on the internet to test new methods of processing and evaluation. Already existing and available GPS and aerogravimetry processing software should become accessible for comparison.

This Study Group reports to Sub-Commission 2.1