온난화에 따른 북태평양 혼합층깊이 및 일차생산변화

Abstract

This study investigates projected changes in the North Pacific Ocean mixed layer depth in response to global warming and their impact on primary new production by analyzing outputs from Coupled Model Intercomparison Projects phase 3 (CMIP3). MLD in the 21st century decreases in most regions of the North Pacific, while the spatial distribution of the MLD is nearly unchanged. The overall shoaling results mainly from intensified upper-ocean stratification caused by both surface warming and freshening. A significant ML decrease (>30 m) is found in the Kuroshio Extension (KE), which is predominantly driven by weakened wind which reduces surface cooling. Associated with the mixed layer shoaling in the KE, the new production will be reduced by 10.7 ~ 40.3 % (medians of twelve models) through decreased amount of nitrate available for primary production. Spring blooms in most models are projected to occur earlier in the KE by 0.2 ~ 1.7 week (medians of twelve models). Although model configuration (e.g., resolution and sub-grid scale parameterization) varies significantly, the response of the KE to global warming appears to be consistent and robust across the models: most of the models used in this study show a decreased MLD in the KE and associated reduction of new production.