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The role of net community production in air‐sea carbon fluxes at the North Pacific subarctic‐subtropical boundary region
Author(s) -
Howard Evan,
Emerson Steven,
Bushinsky Seth,
Stump Charles
Publication year - 2010
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2010.55.6.2585
Subject(s) - subarctic climate , ocean gyre , photic zone , oceanography , environmental science , subtropics , sink (geography) , new production , atmospheric sciences , chlorophyll a , temperate climate , mesoscale meteorology , nutrient , geology , phytoplankton , geography , chemistry , biology , ecology , biochemistry , cartography
The North Pacific subarctic‐subtropical boundary region is an important sink for atmospheric CO 2 , with high annual influx relative to surrounding waters and large seasonal variability. The location of the subarctic‐subtropical gyre boundary is relatively stable, but there is a large seasonal migration of the North Pacific Chlorophyll Front, between ~30°N and ~45°N. To determine the role of biological productivity on the seasonal CO 2 flux, we measured sections of oxygen‐argon gas ratios on cruises across the transition zone in November 1997 (autumn) and September 2008 (summer). A simple upper ocean model was used with the O 2 :Ar data to estimate the net community production (NCP) in the euphotic zone. On both cruises the NCP was highest at the chlorophyll front with average values from 30°N to 45°N of 3.4 ± 2.0 and 8.1 ± 2.7 mmol C m −2 d −1 in autumn and summer, respectively. These values are sufficient to make biologically induced carbon export an important component of the CO 2 drawdown in this region. Processes that control the relatively high NCP at this boundary are not certain, but it has been demonstrated that horizontal convergence of nitrate plays some role.