| title: | Wind wave climate of the Baltic Sea and its dependence on nonlinear effects. |
|---|---|
| reg no: | ETF5762 |
| project type: | Estonian Science Foundation research grant |
| subject: |
1.16. Marine Sciences and Limnology 2.3. Mechanics |
| status: | accepted |
| institution: | TTU Marine Systems Institute |
| head of project: | Tarmo Soomere |
| duration: | 01.01.2004 - 31.12.2007 |
| description: | Estimates of the behaviour of single waves and wave climate in the Baltic Sea are mostly based on wave models designed for ocean conditions. They ignore specific features of relatively short Baltic Sea waves as well as vertical structure of local currents. Their typical resolution (~3 miles) is insufficient to resolve neither the horizontal variability of currents nor the complex shape of the sea and its subbasins. To overcome these shortages, we shall first analyze specific features of wave propagation on vertically structured currents in the framework of the theory of resonant interactions.The goal is to identify the possibilities of energy exchange between wave triads owing to changes in the dispersion relation, to analyse the intensity of triad interactions and, if necessary, to include a relevant parametrisation of such an energy exchange into the existing wave model(s). Since the strong vertical stratification of the Baltic Sea is unique, this energy exchange mechanism is also unique in deep water conditions in the world ocean. Additionally, we shall analyze the geometry and frequency of occurrence of anomalously high wave humps that may theoretically occur when long-crested nonlinear water waves intersect. Applied studies will be concentrated on constructing of high-resolution (1~1/4 miles) models that are verified for particular open or coastal sea areas and that are suitable for reliable estimates of wind wave climate within the areas of interest. The spectral resolution of the models will be extended towards including nonlinear interactions of shorter waves. The improved models will be verified based on in situ wave measurements for several coastal sea areas. They will be used for determining of main properties of wave climate for those areas as well as for the Baltic Proper. In order to improve the reliability of the estimates, analysis of specific features of wind conditions of the Baltic Sea basin will be continued. The statistics and spatial-temporal distribution of extreme waves is a vital part of information about the wave regime. The wave height distribution in the Baltic proper as well as its anomalies owing to topographic refraction in shallow areas has been well understood. As the next step, joint influence of changing wind properties and realistic current field on wave field properties and generation of extreme waves will be analysed. |
| project group | ||||
|---|---|---|---|---|
| no | name | institution | position | |
| 1. | Sirje Keevallik | MSI | vanemteadur | |
| 2. | Kalev Rannat | MSI | teadur | |
| 3. | Tarmo Soomere | TTU Marine Systems Institute | senior scientist, vice-director | |