Hydrophysical experiment "Megapolygon-87" in the northwestern Pacific subarctic frontal zone

The purpose of this paper is to familiarize readers with major results and findings of the biggest multi-institutional Soviet hydrophysical experiment , "Megapolygon-87," conducted in the northwestern Pacific Subarctic Frontal Zone in June-October 1987, Six large-scale, high-spatial-resolution conduc tivity-temperature-depth (CTD) surveys (1653 profiles) and numerous mooring s tan array of 177 buoys deployed within a 500 km x 500 km area) with curre nt meters at four depths provided unique observations of frontal structure, mesoscale and submesoscale eddies, and their evolution and interaction wit h each other. We discuss errors induced in the velocity records by surface waves and show how they can be corrected to a reasonable value. joint analy sis of current meter and CTD data allowed detection of a number of interest ing processes and objects in the study area. Among them are meandering of t he Subarctic Front around its branching point with formation of chains of c yclonic and anticyclonic mesoscale eddies and strong baroclinicity of veloc ity fields with significant difference between the thermocline and abyssal flows. Statistical characteristics of corrected "Megapolygon-87" velocities are compared with preceding measurements in the region.