Results of the analysis of long time series of sea level for June - September, 2009 near the Aniva cape (Sakhalin), recorded by pressure bottom station placed on depth of 12 m are given. There are 394 abnormal big waves, waves satisfying to freak wave amplitude criterion (the wave height exceeds the significant height more then twice) recorded. The amplification during six events exceeds 2.5 times. The cumulative frequency of the abnormal wave appearance is described by the Poisson distribution as follows from the theory of extreme statistics. Freak waves occurred on the average twice a day which is in good comparison with the Raleigh prediction for narrow-band Gaussian wave field.
A brief review of recent studies of internal waves in the Baltic Sea is given. The data of various observations of internal waves in the Baltic region are discussed and a database for the background hydrological parameters that govern the basic appearance of the internal wave shape is introduced. These data sets are employed to select examples of pathways of wave propagation that contain critical points. Numerical modeling of propagation of internal solitary waves across the sea is carried out using the relatively simple model based on Gardner’s equation. This model was chosen due to its clear advantages. It is robust, allows high-resolution calculations with modest computer resources, and is able to reproduce the transformation of internal waves in horizontally inhomogeneous sea. The results of calculations of the transformation of internal solitons in the Baltic Sea along such pathways in a realistic (spatially variable) set of hydrological conditions are presented.
The new version of the program complex intended for numerical modeling of propagation and transformation of internal gravity waves in the ocean, with a finalized unit calculation of a ray of internal waves and with a paralleling of the program, which can significantly speed up the ongoing computation is presented. As a practical example of the proposed study addictive properties of the shelf of the Baltic Sea from the point of view of long internal waves on the basis of the ray approach is offered. The values of the coefficient of capture are calculated and the corresponding maps are constructed.
In this paper software package for numerical modeling of transformation and propagation of internal gravity waves (IGW) in the World Ocean is presented. Short overview of implemented numerical models is given. They are: extended nonlinear evolutionary equation of Korteveg-de-Vries type with combined nonlinearity with variable coefficients (Gardner equation) and ray model reproducing the effect of refraction in an IGW package. The developed software package is unique and topical for this class of geophysical applications. Description of user interface and main working modes of the software are presented.
The properties of extreme wave storms in the Darss Sill area, SW Baltic Sea, are analysed based on waverider data for 1991-2010 and long-term numerical simulations. The long-term significant wave height is HS ~0.7 m and the most frequent wave periods 2-4 s. The largest measured HS is 4.46 m. The typical measured and modelled wave periods differ by up to 2 s. The annual maximum HS has notched behaviour, with an increase for 1958-1990 and since 1993, and a drastic decrease in 1991-1992. The measured annual average and maximum HS have changed insignificantly in 1991-2010 but the threshold for the top 1% of waves has considerably decreased.