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

2012年6月，在意大利和地中海中部上空执行了大地测量-地球物理飞行使命GEOHALO，这是利用德国新型研究飞机HALO进行的第一次科学使命。这一使命的成功是由于几所大学和研究机构的大量合作努力，并由申请人（M. S.）作为使命PI。GEOHALO包括不同的航空大地测量学和地球物理学方法。我们的重点是航空重力测量、激光测高和全球导航卫星系统对飞行轨迹的观测，目的是对意大利及其邻近海域的大面积区域的重力场和进一步的地球科学参数进行一致、公正和均匀的确定。为此，我们的目标是综合利用不同的传感器，即利用两种不同重力仪、一种激光高度计以及GEOHALO飞行使命期间各种全球导航卫星系统天线和接收器获得的数据。使用喷气式飞机导致了航空大地测量学和地球物理学的全新应用。因此，在本项目中，我们将详细研究源自喷气式飞机特殊条件（更高的飞行速度，不同的飞行动力学，更高的海拔，增压舱）的所有方法方面。GEOHALO数据将用于推断意大利区域重力大地水准面，采用不同的技术，如球基函数和最小二乘配置。对不同数据组合以及不同空间尺度分辨率的研究将有助于回答GEOHALO数据在多大程度上能够帮助改善区域和全球的重力场。相反，在GEOHALO使命期间，HALO的远程能力得到充分利用，有几个连续飞行剖面长达1，000多公里，能够将现有的不同但仍然是局部孤立的测量联系起来，以澄清调查区域地基重力数据中的不一致之处。将（改进的）大地水准面和激光测高相结合，将能够推断平均海面地形，并将再次通过独立的数据和/或模型进行评估。对误差和敏感性进行全面分析，特别是对重力场变量进行分析，将有助于为进一步的大地测量地球物理HALO飞行任务确定最佳飞行参数。这一点非常重要，因为必须在科学要求和经济考虑之间取得最佳平衡。

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.