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Update on the Temperature Corrections of Global Air‐Sea CO 2 Flux Estimates
Author(s) -
Dong Yuanxu,
Bakker Dorothee C. E.,
Bell Thomas G.,
Huang Boyin,
Landschützer Peter,
Liss Peter S.,
Yang Mingxi
Publication year - 2022
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 - 10.1029/2022gb007360
Subject(s) - buoy , sea surface temperature , flux (metallurgy) , environmental science , atmospheric sciences , sink (geography) , outgassing , climatology , carbon dioxide , latitude , mixed layer , carbon sink , temperature gradient , meteorology , chemistry , oceanography , geology , climate change , physics , geography , geodesy , organic chemistry , cartography
Abstract The oceans are a major carbon sink. Sea surface temperature (SST) is a crucial variable in the calculation of the air‐sea carbon dioxide (CO 2 ) flux from surface observations. Any bias in the SST or any upper ocean vertical temperature gradient (e.g., the cool skin effect) potentially generates a bias in the CO 2 flux estimates. A recent study suggested a substantial increase (∼50% or ∼0.9 Pg C yr −1 ) in the global ocean CO 2 uptake due to this temperature effect. Here, we use a gold standard buoy SST data set as the reference to assess the accuracy of insitu SST used for flux calculation. A physical model is then used to estimate the cool skin effect, which varies with latitude. The bias‐corrected SST (assessed by buoy SST) coupled with the physics‐based cool skin correction increases the average ocean CO 2 uptake by ∼35% (0.6 Pg C yr −1 ) from 1982 to 2020, which is substantially smaller than the previous correction. After these temperature considerations, we estimate an average net ocean CO 2 uptake of 2.2 ± 0.4 Pg C yr −1 from 1994 to 2007 based on an ensemble of surface observation‐based flux estimates, in line with the independent interior ocean carbon storage estimate corrected for the river induced natural outgassing flux (2.1 ± 0.4 Pg C yr −1 ).