| Summary: | Proper estimation of air flow over sea waves plays a key role in wave, storm surge, wind field prediction. Most hydrological models assume the drag coefficient Cd to be dependent only on the local wind speed. However this is a simplification. As it is known (Smith et al., 1991; Donelan, 1982, 1997; Janssen, 1991), among other factors, the drag coefficient depends also on the stage of wave development. The aim of the work is the study of wave age dependent drag coefficient and wave induced stress in the Baltic Sea. The wave model WAM4, which is a coupled model, is used for study of wave age, wave stress and drag coefficient in the Baltic Sea during storm. It is shown in the paper that as expected significant variability of wave field is characteristic for the Baltic and young wind waves (with wave age 10-20) dominate. Spatial distribution of wave induced stress shows large variability as well. There exist situations when contribution of wave stress to the total stress is greater then 60% over the whole Baltic. Enhancement of wave age dependent drag coefficient (in the comparison with drag coefficient dependent only on wind speed, calculated using the Charnock formula) exceeds 50%.
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