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Nicholson, D. P., Woods Hole Oceanographic Institution, Woods Hole, USA, dnicholson@whoi.edu
Stanley, R. H., Woods Hole Oceanographic Institution, Woods Hole, USA, rstanley@whoi.edu
Barkan, E. ., The Hebrew University, Jerusalem, Israel, eugenib@cc.huji.ac.il
Karl, D. M., University of Hawaii, Honolulu, USA, dkarl@hawaii.edu
Luz, B. ., The Hebrew University, Jerusalem, Israel, boaz.luz@huji.ac.il
Quay, P. D., University of Washington, Seattle, USA, pdquay@uw.edu
Doney, S. C., Woods Hole Oceanographic Institution, Woods Hole, USA, sdoney@whoi.edu

EVALUATING TRIPLE OXYGEN ISOTOPE ESTIMATES OF GROSS PRIMARY PRODUCTION AT THE HAWAII OCEAN TIME-SERIES AND BERMUDA ATLANTIC TIME-SERIES STUDY SITES

The triple oxygen isotopic composition of dissolved oxygen (17Δ) is a promising tracer of gross oxygen productivity (GOP) providing new information about ecosystem metabolism and carbon cycling. We added oxygen isotopes to a one-dimensional mixed layer model to analyze the dynamics of oxygen isotopes in the upper ocean at the Bermuda Atlantic Time-series Study (BATS) and Hawaii Ocean Time-series (HOT). Model results were compared to multi-year observations at each site. Entrainment of high 17Δ thermocline water into the mixed layer caused a bias in determining mixed layer GOP from 17Δ. At both BATS and HOT, entrainment bias was significant throughout the year and resulted in an annually averaged overestimate of mixed layer GOP of 50 to 70%. After correcting for mixed layer bias, observations were consistent with a mixed layer GOP rate twice that of 14C based net primary productivity (NPP). In the seasonal thermocline at BATS, however, a significantly higher GOP:NPP ratio, or large lateral fluxes of 17Δ must be invoked to explain 17Δ field observations.

Session #:S02
Date: 02-18-2011
Time: 08:45

Presentation is given by student: No