Description: In austral winter, biological productivity at the Angolan shelf reaches its maximum. The alongshore winds, however, reach their seasonal minimum suggesting that processes other than local wind‐driven upwelling contribute to near‐coastal cooling and upward nutrient supply, one possibility being mixing induced by internal tides (ITs). Here, we apply a three‐dimensional ocean model to simulate the generation, propagation, and dissipation of ITs at the Angolan continental slope and shelf. Model results are validated against moored acoustic Doppler current profiler and other observations. Simulated ITs are mainly generated in regions with a critical/supercritical slope typically between the 200‐ and 500‐m isobaths. Mixing induced by ITs is found to be strongest close to the coast and gradually decreases offshore thereby contributing to the establishment of cross‐shore temperature gradients. The available seasonal coverage of hydrographic data is used to design simulations to investigate the influence of seasonally varying stratification characterized by low stratification in austral winter and high stratification in austral summer. The results show that IT characteristics, such as their wavelengths, sea surface convergence patterns, and baroclinic structure, have substantial seasonal variations and additionally strong spatial inhomogeneities. However, seasonal variations in the spatially averaged generation, onshore flux, and dissipation of IT energy are weak. By evaluating the change of potential energy, it is shown, nevertheless, that mixing due to ITs is more effective during austral winter. We argue that this is because the weaker background stratification in austral winter than in austral summer acts as a preconditioning for IT mixing.

Description: Against the background of EnMAP preparation analyses have been carried out on the status of research in various areas of hyperspectral remote sensing for the use of existing algorithms in the EnMAP application box. The aim was to compose the status of research in Germany and internationally. Therefore, in various fields of expertise applied and accordingly available algorithms and products based on hyperspectral data has been evaluated and documented. The intention has been to demonstrate and to evaluate the added value of hyperspectral remote sensing to multispectral methods for each product. For this purpose analyses have been carried out by different research groups which were based on the specialty and the experience of each group. Hereby a summary was created of each major application perspective and the relevant remote sensing derived variables and significant processing algorithms (state-of-the-art) belonging to this context. Based on this, the research delivers, as a result, a recommendation which of the algorithms should be implemented into the Applikationsbox of EnMAP. Tests of the algorithms or their implementation were not part of the analyses. However, notes have been given on what algorithms should be tested in the context of a detailed preparation phase. An assessment to the further R & D requirements in the development of algorithms has been made on this basis.