Investigation of the regional GRAVity field, geoid and mean sea-surface topography in ITalY and at the adjacent seas using airborne gravimetry and laser altimetry data acquired during the GEOHALO mission

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Being the the first scientific mission utilizing the new German research aircraft HALO the geodetic-geophysical flight mission GEOHALO was carried out over Italy and the central Mediterranean Sea in June 2012. The success of this mission was due to a large cooperation effort of several universities and research institutions and was led by the applicant (M.S.) as the mission PI. GEOHALO comprises different airborne methods of geodesy and geophysics. Focussing on airborne gravimetry, laser altimetry and GNSS observations of the flight trajectory we aim to carry out a consistent, unbiased and homogeneous determination of the gravity field and of further geoscientific parameters over the large-scale area of Italy and its adjacent seas. To do so, we aim to make use of a combination of different sensors, namely to utilize data gained by two different gravimeters, a laser altimeter and various GNSS antennas and receivers during the GEOHALO flight mission. Employing a jet aircraft results in a completely novel application of airborne geodesy and geophysics. Therefore, within the project we will investigate in detail all methodic aspects originating from the special conditions of the jet aircraft (higher flight velocity, different flight dynamics, higher altitude, pressurized cabin). The GEOHALO data will be used to infer a regional gravimetric geoid over Italy applying different techniques like spherical base functions and least-squares collocation. The investigation of different data combinations as well as of the resolution at different spatial scales will help to answer to what extent the GEOHALO data can assist an improvement of the gravity field both regionally and globally. On the contrary, the long-range capability of HALO, fully employed with several continuous flight profiles of more than 1,000 km length during the GEOHALO mission, enables to connect existing different but still locally isolated surveys in order to clarify inconsistencies in the ground-based gravity data in the area of investigation. A combination of the (improved) geoid and laser altimetry will allow to infer the mean sea-surface topography which will again be evaluated by independent data and/or models. A thorough error and sensitivity analysis, especially in terms of the gravity field variables, shall help to identify optimal flight parameters for further geodetic-geophysical HALO missions. This is of eminent importance since an optimal balance has to be reached between scientific requirements and economic considerations.