The results of the Laboratory of Nonlinear Dynamical Systems (2014)

Prof. S.V. Prants is the winner of an International Zaslavsky Award in nonlinear science and complexity.

According to voting at the Institute Scientific Council, the following result was recognized as the most important one in the Institute and included among the most important results in the Russian Academy of Sciences in 2014

Lagrangian simulation of near-surface transport in the Kuroshio-Oyashio frontal zone after the Fukushima accident

Lagrangian approach is applied to study near-surface transport in the Kuroshio-Oyashio frontal zone using a simulation with synthetic particles advected by the AVISO altimetric velocity field. Fukushima derived cesium isotopes are used as tracers to study transport and mixing in the area after the 11 March 2011 tsunami that caused a heavy damage of the Fukushima nuclear power plant. A special technique is proposed and applied to find out the origin of water masses in cold-core cyclonic rings pinched off from the jet in summer 2011. Lagrangian maps provide the evidence of transport across the Kuroshio Extension jet. Tracking maps are computed to trace the origin of water parcels with measured levels of 134 Cs and 137 Cs concentrations collected in two research vessel cruises in June and July 2011. It is shown that Lagrangian simulations are useful to finding the surface areas that are potentially dangerous due to the risk of radioactive contamination. The results of simulation are supported by tracks of surface drifters which were deployed in the area.

Figure. a), c), d) AVISO velocity field to the east off Japan with in situ measurements of  cesium concentration (color lines) in June and June 2011 and tracks of surface drifters imposed. b) The Lagrangian map shows the Kuroshio ring to the south of the Kuroshio Extension jet (black cross in panel с)) with radioactive water (green particles) and tracks of the drifters captured by the ring (black squares). Panel b) shows the result of the backward-in-time integration of advection equations from 30 June to 11 March 2011 with red particles coming through the southern boundary of the shown box. Shadows of grey color code the particles coming to the box from the region between 31 and 37 N.

1. S.V. Prants, M.V. Budyansky, M.Yu. Uleysky. Lagrangian study of surface transport in the Kuroshio Extension area based on simulation of propagation of Fukushima-derived radionuclides. Nonlinear Processes in Geophysics. V.21, 279-289, 2014. 

2. S.V. Prants. Chaotic Lagrangian transport and mixing in the ocean. The European Physical Journal Special Topics. V. 223, 1-21 (2014).