G02 Static Gravity Field Models and Observations

IAG (Geodesy)

29-Jun-2015, 15:00 - 16:30

Abstract content:

Feasibility and performance assessment of a new gravitational gradiometer for airborne surveys

During the past decade, satellite missions such as GRACE and GOCE have considerably improved global gravitational field models. Albeit these models have been beneficial to various fields of geosciences, their accuracy at wavelengths shorter than 100 km is not sufficient to address many geodetic and geophysical questions. To overcome this limitation and access the short wavelengths of the gravitational field, the development of new sensors is crucial. In this respect, gravitational gradiometry is particularly appropriate as it enables to amplify the high-frequencies of the gravitational field spectrum.

Here, we put forward and analyze the adaptation to airborne conditions of electrostatic technologies developed at ONERA for space accelerometers. GREMLIT is a gradiometer concept specially designed for this purpose. The sensor is composed of an assembly of 4 planar electrostatic accelerometers which enables together with gyrometer data to measure the 3 horizontal gradients: Vxx, Vxy and Vyy. After an overview of its operational principle and main components, a detailed error budget on the final gravitational gradients is given. This error budget is based on the results of an end-to-end numerical simulation of a survey performed with GREMLIT under realistic airborne conditions. We show that after a calibration of the gyrometer’s bias, it is possible to reach a precision below 2 E in the measurement frame of reference and in the local geodetic frame after, in the latter case, an along-track Gaussian filtering.

Finally, we briefly examine and discuss how the electrostatic accelerometer measurements can be enhanced thanks to the complementary use of laser interferometry, as a first step towards optical gradiometry.
D. Karim1, I. Panet2, B. Christophe3, B. Foulon3.
1Institut für Erdmessung, Hannover, Germany.
2IGN, LAREG, Paris, France.
3ONERA, DMPH, Châtillon, France.


Gravitational gradiometry     sensors     airborne survey     electrostatic accelerometry     Laser interferometry