Thepresentpaper reviews thecontemporary stateofdefinitionand theoryof thegeoid. Key features are: quasigeoid, externalgravitational field from satellites and its analytical downward continuation to the Earth's interior, data combination by least-squares collocation, and a new view of gravity reduction. This is done under the modern systematic perspective provided by the possibility of a purely ...

The use of ground gravity data in wellsurveyed areas, continued upward to satellite altitude, is one of the most promising external absolute in-orbit calibration/validation methods for GOCE satellite gravity gradient (SGG) observations. Based on a synthetic gravity test environment – providing in addition to statistical error information also absolute error estimates – several upward continuati...

Colophon Quality assessment of satellite-based global gravity field models Contents Summary iii Samenvatting iv Acknowledgements v Abbreviations vi 1 Introduction 1

GOCE gravity fields define a new standard concerning spectral resolution of satellite-only models, and provide a very high precision in the longand medium wavelength part of the gravity field up to a spherical harmonic degree of about 250. Combining GOCE with GRACE data, which gives in addition very accurate information for the long wavelength part, results in the current performance status of ...

The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10-100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In...

Gravity waves are an important driver for the atmospheric circulation and have substantial impact on weather and climate. Satellite instruments offer excellent opportunities to study gravity waves on a global scale. This study focuses on observations from the Atmospheric Infrared Sounder (AIRS) onboard the National Aeronautics and Space Administration Aqua satellite and the Infrared Atmospheric...

The NUTS (NTNU Test Satellite) is a satellite being built in a student CubeSat project at the Norwegian University of Science and Technology. The project was started in September 2010 and is a part of the Norwegian student satellite program run by NAROM (Norwegian Centre for Space-related Education). The NUTS project goals are to design, manufacture and launch a double CubeSat by 2014. The sate...

The launch of the satellite GRACE heralds a new era of high precision, time-varying, satellite measurements of the Earth's gravity field. An important aspect of the mission is to consider how the predicted high-accuracy gravity data might be validated. Two kinds of validation have been proposed; the first is internal, whereby the data are modeled for self – consistency to verify the internal ac...

The Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite aimed at determining the Earth's mean gravity field. GOCE delivered gravity gradients containing directional information, which are complicated to use because of their error characteristics and because they are given in a rotating instrument frame indirectly related to the Earth. We compute gravity gradients in grids...