Goes¹, Joaquim I., Helga do R. Gomes¹, Atsamon Limsakul² and Toshiro Saino^{2, 3 ,4
1}Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine 04575, USA, Tel: 207-633-9628, Fax: 207-633-9628, E-mail: jgoes@bigelow.org, ²Institute of Hydrospheric and Atmospheric Sciences, Nagoya University, Nagoya 464-8601, Japan, ³Earth Observation Research Centre, National Space Development Agency of Japan, Tokyo, 106-0032, Japan and ⁴Frontier Research System for Global Change, 3173-25, Yokohama 236-0001, Japan

The rise and fall of El Niño’s and their impact on carbon sequestration in the North Pacific Ocean

The subarctic Pacific Ocean experiences strong climate-modulated seasonal, interannual to decadal variations in meteorological and physical oceanographic conditions, which can have a profound influence on biological processes and carbon cycling in the region. A satellite database beginning from 1997 provided us with evidence of strong interannual variations in the supply of inorganic nitrate and new production in the subarctic Pacific in association with the El Niño event of 1997. Although this data allowed us to view and describe large changes in new production along the entire breadth of the subarctic Pacific basin, our accessibility to a 25-year database of shipboard measurements enabled us to better focus on the western subarctic Pacific. Thus, in addition to the primary motive of corroborating our results from satellites, this exercise allowed us to obtain a clearer picture of the mechanistic connections between the atmosphere and the oceans, and the biological response to these changes. The results from this study make a compelling case that the primary driver for interannual variations in biological production in the western subarctic Pacific is the strength of the wintertime monsoonal winds. These winds can be particularly strong during El Niño years, when the Aleutian Low intensifies and moves southeastwards. During this period oceanographic conditions undergo several changes as is evident in the satellite and shipboard data. These changes in tandem, contribute to an increase in the supply of nutrients as well as an increase in the overall area of the North Pacific coming under influence of high nutrients. Unusually calm springs that follow these windy winters provide water column stability required for phytoplankton to benefit from the availability of nutrients. Both the satellite and shipboard showed how these conditions were reversed following the transition to La Niña conditions.