Luftgestützte LiDAR-Messungen der Meeresoberfläche in Küstengebieten

Abstract This thesis describes the remote sensing technique, the data processing and the results obtained with measurements of the sea surface using an airborne LiDAR (Light Detection And Ranging) system in the complex coastal area of the German Bight. Changes in the sea surface properties behind offshore wind parks are proven for the first time. After a brief introduction into physical oceanography with focus on surface waves, the LiDAR instrument and particular adaptions in terms of hard- and software as well as the integration into the research aircraft to employ the system in coastal areas are discussed and the data processing of raw measurements is described. Different data sources and their relevant features are mentioned, whereupon mathematical calculations applied in from the field of ocean engineering are adapted for the use on LiDAR-measurements. These techniques are validated through the evaluation of a short flight segment close to a moored wave motion sensor with comparisons of significant wave height. Subsequently, the calculations to obtain wave spectra are used to conduct two case studies with differing sea state and wind direction. In the case study where a growing sea was present, the first evidence of a wake effect in the ocean wave spectrum downwind of an offshore wind park is shown. The own achievement of this thesis includes the development of the complete measurement chain up to data processing techniques. These extensive measurements denote a unique dataset of surface properties in the German Bight, which closes the observation gap between punctual buoy data and satellite measurements. In between processing steps, the dataset reveals relevant parameters that are useful to validate wind-wave-models and will help to refine satellite data analysis.