Physical Oceanography (Apr 2023)
Features of Forming the Alongcoastal Circulation of the Coastal Ecotone Waters nearby the Southern Coast of Crimea
Abstract
Purpose. The study is aimed at expanding the notions on the features of forming the mode characteristics, vertical structure and interannual variability of the costal ecotone water circulation nearby the Southern coast of Crimea, as well as on the characteristics, conditions and lifetime of bimodal structure of the coastal current directions. Methods and Results. New scientific results were obtained with the regard for systematizing and analyzing the already published results on the problem under study. The preset tasks were solved using the monitoring data on variability of the coastal current vertical structure for 2002–2021 obtained through a set of domestic current meters installed at the stationary oceanographic platform of the Black Sea Hydrophysical Sub-Satellite Polygon of Marine Hydrophysical Institute. The materials on the currents’ vector base which had passed state registration were processed according to the technique developed on the basis of the standard methods of digital filtering and mathematical statistics. It was found that nearby the Black Sea coast, there existed two different modes of water circulation: the stationary monomodal alongcoastal current and the bimodal modulation of the direction of total alongcoastal flow induced by the intense hydrodynamic disturbances. At all the horizons near Cape Kikineiz, the reverse mode of bimodal structure was formed mostly due to the contribution of fluctuations with the periods up to 3 days, which constituted 98%, whereas the contribution of those with the periods 3–4 days was 2%. A significant decrease in the annual average velocity of a monomodal current changed the conditions for a bimodal structure existence in the near-surface layer where the period of oscillations forming a reverse mode, had increased in 2020 to 5 days. Conclusions. The results obtained expand our notions on the features of the coastal water circulation mode, and on the conditions and characteristics of the coastal current bimodal structure formed near Cape Kikineiz mostly due to a significant contribution (to 91%) of the fluctuations with periods up to 2 days. The prospect for further development both of the research techniques and the possibility of analyzing quantitative estimates of the coastal current variability including the interannual range are demonstrated.
