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Influence of biological carbon export on ocean carbon uptake over the annual cycle across the North Pacific Ocean
Author(s) -
Palevsky Hilary I.,
Quay Paul D.
Publication year - 2017
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1002/2016gb005527
Subject(s) - oceanography , flux (metallurgy) , carbon cycle , dissolved organic carbon , advection , environmental science , mixed layer , annual cycle , transect , pacific decadal oscillation , biological pump , new production , climatology , pacific ocean , phytoplankton , geology , nutrient , chemistry , ecosystem , biology , ecology , physics , organic chemistry , thermodynamics
We evaluate the influences of biological carbon export, physical circulation, and temperature‐driven solubility changes on air‐sea CO 2 flux across the North Pacific basin (35°N–50°N, 142°E–125°W) throughout the full annual cycle by constructing mixed layer budgets for dissolved inorganic carbon (DIC) and p CO 2 , determined on 15 container ship transects between Hong Kong and Long Beach, CA, from 2008 to 2012. Annual air‐sea CO 2 flux is greatest in the western North Pacific and decreases eastward across the basin (2.7 ± 0.9 mol C m −2 yr −1 west of 170°E, as compared to 2.1 ± 0.3 mol C m −2 yr −1 east of 160°W). East of 160°W, DIC removal by annual net community production (NCP) more than fully offsets the DIC increase due to air‐sea CO 2 flux. However, in the region west of 170°E influenced by deep winter mixing, annual NCP only offsets ~20% of the DIC increase due to air‐sea CO 2 flux, requiring significant DIC removal by geostrophic advection. Temperature‐driven solubility changes have no net influence on p CO 2 and account for <25% of annual CO 2 uptake. The seasonal timing of NCP strongly affects its influence on air‐sea CO 2 flux. Biological carbon export from the mixed layer has a stronger influence on p CO 2 in summer when mixed layers are shallow, but changes in p CO 2 have a stronger influence on air‐sea CO 2 flux in winter when high wind speeds drive more vigorous gas exchange. Thus, it is necessary to determine the seasonal timing as well as the annual magnitude of NCP to determine its influence on ocean carbon uptake.