Investigation of Oceanic circulation climatic variability using Sarkisyan's techniques “diagnosis–adjustment” and JEBAR

Abstract

This paper presents a development of the methodology for studying ocean circulation using numerical modelling proposed by the Professor A. S. Sarkisyan, who is a founder of contemporary numerical oceanography. His 100th anniversary is upcoming in 2026. A brief description of his main contributions to the development of ocean dynamics physical models and numerical algorithms for their solution is presented. These are the concept of the Joint Effect of Baroclinicity And bottom Relief (JEBAR), the formulation of the problem in terms of sea level, a heuristic method for dynamical agreement between baroclinic density and currents based on the diagnosis–adjustment method (DAM), and its use in solving the forward problem of four-dimensional analysis of observational data. It is shown that the DAM has proven a versatile technique and productive tool for studying the mid- and long-term variability of the North Atlantic thermohaline circulation. Our experiments demonstrate the successful application of this method to studying ocean climate variability. For the first time, it was shown that the Atlantic Multidecadal Oscillation (AMO) is driven by the thermohaline circulation, with positive and negative temperature and salinity anomalies circulating along the Atlantic Meridional Overturning Circulation (AMOC) waters, sometimes rising to the surface, sometimes sinking into the deep ocean. This is what forms the well-known warm and cold phases of the AMO. In addition, the existence of a three-jet structure in the Antarctic Circumpolar Current was also confirmed using the DAM, and the phenomenon of deep water isotherm upwelling in the Weddell Sea was studied.