동해 혼합층 변동및 관련 클로로필 변화

Abstract

We investigates year-to-year variability of springtime chlorophyll a (CHL-a) concentration in association with ocean mixed layer depth (MLD) in the East Sea (Japan Sea). MLD data were obtained from 1/12° Global HYbrid Coordinate Ocean Model (HYCOM) for the period (2004-2010). In 2008, CHL-a concentration in the Ulleung basin in April reaches a maximum (8 times larger than the other years) for the period (2004-2010). The increase of the spring CHL-a concentration in 2008 is attributed to considerable deeper winter mixed-layer (about 2 times larger than normal years) that probably entrains more deep-ocean nutrients into upper ocean, making favourable spring bloom condition. The larger winter MLD in 2008 is caused by intensified wind and ocean surface cooling that are associated with strengthened Siberian high and Aleutian low. On the other hand, spring CHL-a in 2004 is not elevated significantly, although the winder MLD deepens considerably. Deeper mixed layer in spring seems to prohibit phytoplankton bloom in 2004 through unfavourable light condition. Difference responses of spring CHL-a to winter MLDs in two years (2004 and 2008) suggest that springtime stratification also plays a crucial role in phytoplankton bloom in the East Sea (Japan Sea).