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Recent technological advances in optical atomic clocks are opening newperspectives for the direct determination of geopotential differences betweenany two points at a centimeter-level accuracy in geoid height. However, so fardetailed quantitative estimates of the possible improvement in geoiddetermination when adding such clock measurements to existing data are lacking.We present a first step in that direction with the aim and hope of triggeringfurther work and efforts in this emerging field of chronometric geodesy andgeophysics. We specifically focus on evaluating the contribution of this newkind of direct measurements in determining the geopotential at high spatialresolution (~ 10 km). We studied two test areas, both located in France andcorresponding to a middle (Massif Central) and high (Alps) mountainous terrain.These regions are interesting because the gravitational field strength variesgreatly from place to place at high spatial resolution due to the complextopography. Our method consists in first generating a synthetic high resolutiongeopotential map, then drawing synthetic measurement data (gravimetry and clockdata) from it, and finally reconstructing the geopotential map from that datausing least squares collocation. The quality of the reconstructed map is thenassessed by comparing it to the original one used to generate the data. We showthat adding only a few clock data points (less than 1 % of the gravimetry data)reduces the bias significantly and improves the standard deviation by a factor3. The effect of the data coverage and data quality on the results isinvestigated, and the trade-off between the measurement noise level and thenumber of data points is discussed.

Determination of a high spatial resolution geopotential model using atomic clock comparisons