ИСТИНА

Research on a square polygon composed of 25 oceanographic stations in the Vema fracture zone of the Mid-Atlantic Ridge was carried out during the 22nd cruise of R/V "Akademik Ioffe" in 2006. LADCP currents measurements were performed on each station. Such detailed current measurements were performed for the first time in this region. In this study the transport of water mass inside the polygon is assessed. The LADCP data is compared with geostrophic flows velocities and transport, which are calculated according to different equations of state using the CTD data. AVISO ADT data and higher layers of LADCP data were used for the correction of geostrophic velocities to absolute velocities. Results of geostrophic velocities calculations weakly correlate with direct measurements data. We believe that this big difference in results occurs due to near-bottom triangles and ageostrophic factors. Ageostrophic factors (aliasing, internal waves, wind-driven and tidal currents) could lead to errors of geostrophic currents estimations, especially in the top and near-bottom layers. According to the balance method of water transport, the balance is observed mostly in the intermediate layers. In the top and in the bottom layers, water transport mostly does not match the balance. Thus, calculation of the correction to geostrophic currents estimation would improve accuracy in geostrophic currents and water mass transport calculation.