북태평양 혼합층깊이 변화와 클로로필변화와의 관계

Abstract

Mixed layer depth (MLD) affects phytoplankton dynamics through controlling the availability of nutrients and light in the upper ocean. This study investigates variability of MLD and its relation with chlorophyll (CHL) in the North Pacific Ocean on seasonal to year-to-year timescales. Applying a variable density criterion the North Pacific MLD field was calculated from SODA (Simple Ocean Data Assimilation) version 2.1.6 covering 51 years from January 1958 to December 2008. The variability of MLD is well correlated with CHL variability in some regions in the North Pacific Ocean, including the Kuroshio Extension (KE). For example, increased MLDs in the years of 2003–2007 compared with values in the years of 1998–2002 correspond to enhanced CHLs in the KE. The good correspondence between MLD and CHL suggests that increased MLD helps to entrain deep nutrients into the upper ocean and thus to maintain high CHL in the KE. This study also suggests possible contribution of ENSO to CHL variability through MLD change at the mid-latitudes in the North Pacific Ocean.