Primary productivity in the Drake Passage and its vicinity
Four cruises were conducted in the region circumscribed by 52∼66°S and 70∼46°W which include the Drake Passage, south-western Scotia Sea, and north-eastern Bellingshausen Sea during austral summer in 2001∼2003 using RV UZMOGEOLOGIYA. And, these researches were conducted as a part of Korea Antarctic Research Program (15th∼18th).Drake Passage is located at the south of the Continent of South America, and ACC (Antarctic Circumpolar Current) flow is most strong in this area. Polar front is located circa 57∼63°S in the Drake Passage (Moore et al., 1999), and this area is known for typical HNLC (High Nutrient and Low Chlorophyll) sea. However, in the shelf zone and near the Continent of Antarctica, high chlorophyll concentrations are seasonally appeared due to the effects of water inflow from Bellingshausen Sea and Weddell Sea.Current estimates of the oceanic sink of atmospheric CO2 based on global pCO2 data is approximately 2.2 Gt C yr-1 (Giorgio and Duarte, 2002). In the Southern Ocean which centered around 50°S (35 ~ 60°S), a large oceanic sink of atmospheric CO2 occurs, which is relatively larger in Atlantic and Indian Ocean than in Pacific Ocean, and about 20% of the oceanic sink of atmospheric CO2 (0.47 Gt C yr-1) occurs south to 50°S (Treguer and Pondaven, 2002).However, it is difficult to estimate primary production in the Southern Ocean with a reasonable accuracy. The difficulty includes inaccurate retrieval of chlorophyll and uncertainty of vertical chlorophyll distribution from satellite data. Photosynthetic parameters are also different from those of temperate ocean due to significantly low temperature.Here we attempt to overcome some of these problems, and we calculated seven year's primary productivity by using SeaWiFS and other remote sensing data, and compared with directly measured primary production. The results and problems in such approach are discussed.