Variability of the North Pacific circulation model under the surface forcing from re-analysis data

The 3-D finite element North Pacific Circulation Model developed in the Novosibirsk Institute of Computational Mathematics and Mathematical Geophysics (ICMMG) is used to study the sensitivity of the North Pacific circulation to the varying boundary conditions at the sea surface. The initial conditions have been taken from the results of diagnostic numerical experiments of climatic circulation which were carried out on the basis of climatic temperature and salinity data of Levitus, 1994 and wind-stress of Hellerman, Rosenstein, 1982. The numerical experiment was concerned with the spin-up prognostic experiments for the study of the variations of the North Pacific hydrophysical characteristics to real forcing on the surface. For this purpose the ten-days mean distribution of the surface forcing was adopted from the European Center for Medium-Range Weather Forecast Ensemble Simulation, 1987. The spin-up period was chosen as a period of the pre-El-Nino and El-Nino event 1982. Satellite data for this period were used as the control data to compare the simulation results with the real processes. Simulation experiment for two-and-half year period with the climatic initial state and varying boundary conditions at the sea surface was carried out. The results show the development of the positive temperature anomaly in the eastern part of the tropical Pacific, propagating at thermohaline depth from the west to this region. The analysis of these processes and the comparison with the satellite derived distributions are done in the paper.