Science Objectives and Applications

The primary Science Objective of the GRACE mission is to provide with unprecedented accuracy, global and high-resolution estimates of the constant and time-variable part of the Earth's gravity field.

Secondary objective is the measurement of several hundred globally distributed profiles per day of the excess delay or bending angle of GPS measurements caused by the atmosphere and ionosphere, which can be converted to total electron content and/or refractivity, respectively.

Typical GRACE Science Applications are the improved knowlege of the mean geoid, which will lead - in conjunction with altimetry and in-situ data - to significant advances in oceanographic, geodetic or solid Earth science studies such as

• oceanic heat flux,
• long term sea level change,
• upper oceanic heat content,
• absolute surface geostrophic ocean currents or
• precise positioning, orbit determination and levelling.

Estimates of time variable components of the gravity field will help for a better understanding of time variable processes in oceanography, hydrology, glaciology or solid Earth sciences like

• deep ocean current changes,
• large-scale evapotranspiration,
• soil moisture changes,
• mass balance of ice sheets and glaciers,
• changes in the storage of water and snow of the continents,
• mantle and lithospheric density variations,
• postglacial rebound or
• solid Earth's isostatic response.

Additionally GPS occultation measurements and its derived quantitities of temperature and water vapor will be a contribution to climate variabilty studies. Furthermore these observations will lead to an improved resolution of the fine structure of the ionosphere.