| Summary: | Since early 2002, the Gravity Recovery and Climate Experiment (GRACE) twin satellite mission provide the scientific community with accurate monthly maps of the Earth's gravity field. On short time-scale, the observed variations are mainly related to a redistribution of water on the Earth's surface. This new data set has lead to a leap forward in our understanding of the various components of the Earth's water cycle, and their mutual interaction. The GRACE data provided by the science teams are contaminated by noise, hampering the interpretation of the observations. The first part of this thesis describes a statistical filtering method which removes the majority of the noise and allows utilization of the GRACE data at their full potential. Using the filtered observations, variations in the water budget of the climate system have been studied. A method was developed to obtain a picture of the mass balance of the Greenland ice sheet at a regional scale. From the research in this dissertations, it shows that Greenland lost about 200 cubic kilometers of ice each year on average between 2003 and 2008, causing a global mean rise of sea level by 0.5 mm/yr. An acceleration of the thinning of the ice sheet is observed, with a contribution of 0.75 mm/yr to global mean sea level rise in the last two years. Furthermore, the GRACE observations have been used to identify the seasonal exchange of roughly three thousand gigatons of water between land and ocean, and, in combination with sea level measurements from altimeter satellites, to constrain the cycle in heat content of the ocean. Finally, a method was developed to model the passive adjustment of the sea level to changes in the gravity field of the earth, induced by mass redistribution on the continents. Including this 'selfgravitation effect' into numerical ocean model would result in a better agreement between modeled and observational ocean data in several regions. Department of Space Engineering Aerospace Engineering
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