남극해 대서양해역의 식물플랑크톤 생물량의 계절 변동성

Abstract

11-year (1997-2008) weekly and monthly time-series of satellite ocean color data have been examined to understand the dominant temporal and spatial patterns of chlorophyll-a in the southwest Atlantic sector of the Southern Ocean. Using empirical orthogonal function analysis and K-means classification, we classified the study area into 8 regions, which is in good accordance with the oceanographic and topographic features. Examination of the time-series of chlorophyll-a in each region revealed that contrary to our expectation, regular seasonal phytoplankton blooms were observed only in a limited area. Of the 8 regions, only 2 showed typical seasonal blooms and 1 showed weak seasonality while other regions show irregular seasonal blooms of variable duration. We attribute the absence of regularity in seasonal blooms to relatively shallow winter mixing which prevents entrainment of the limiting micronutrient. Interannual variability of the surface chlorophyll in some regions also revealed longer periodicity (~6 years). The periodicity seemed to relate to ENSO and is thought to be related to sea ice dynamics influenced by the Antarctic Circumpolar Current.