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Role of the Southern Annular Mode (SAM) in Southern Ocean CO 2 uptake
Author(s) -
Lenton Andrew,
Matear Richard J.
Publication year - 2007
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 - 10.1029/2006gb002714
Subject(s) - biogeochemical cycle , oceanography , climatology , environmental science , ocean current , pacific ocean , ocean heat content , carbon cycle , mode (computer interface) , ocean general circulation model , climate change , atmospheric sciences , general circulation model , geology , chemistry , biology , ecosystem , environmental chemistry , ecology , computer science , operating system
A biogeochemical ocean general circulation model, driven with NCEP‐R1 and observed atmospheric CO 2 history, is used to investigate and quantify the role that the Southern Annular Mode (SAM), identified as the leading mode of climate variability, has in driving interannual variability in Southern Ocean air‐sea CO 2 fluxes between 1980 and 2000. Our simulations show the Southern Ocean to be a region of decreased CO 2 uptake during the positive SAM phase. The SAM induces changes in Southern Ocean CO 2 uptake with a 2‐month time lag explaining 42% of the variance in the total interannual variability in air‐sea CO 2 fluxes. Our analysis shows that the response of the Southern Ocean to the SAM is primarily governed by changes in ΔpCO 2 (67%), and that this response is driven by changes in ocean physics that control the supply of nutrients to the upper ocean, primarily Dissolved Inorganic Carbon (DIC). The SAM is predicted to become stronger and more positive in response to climate change and our results suggest this will decrease the Southern Ocean CO 2 uptake by 0.1PgC/yr per unit change in the SAM.