TRANSFORMATIONS AND EFFECTS OF INTERNAL WAVES IN THE NEARSHORE REGION OF SEA

Abstract

Analysis of results of field experiments in the near-shore region of the Peter the Great Bay (the Sea pf Japan) is made from the point of view of internal waves (IW) influence on biological and geomorphologic processes in the shelf zone of sea. The main measured parameters were fluctuations of temperature, pressure and current velocity in the near-bottom layer in the near-shore region with bottom depth of 20–30 m. Fluctuations of temperature were measured with the help of anchored strings of 20–30 thermistors with 0.5 m interval, fluctuations of current velocity were measured at 10–15 levels with 1–3 m intervals. The typical for shoreward propagated IW was their nonlinear transformation with formation of stable discreet boluses - water volumes with cold cores, separated from surrounding medium by high-gradient layers. Propagating into shallow regions, IW stimulate mixing, bottom sediments resuspension and near-shore region ventilation. The boluses can propagate farther into shallow regions where continuous picnocline is absent, supplementing effects of IW and amplifying them. It is shown that biological effects of IW and boluses are caused by their considerable impact on the main parameters defining primary production of phytoplankton: biogens concentration, illumination, and fluctuations of temperature.