# A joint atmosphere-ocean inversion for the estimation of seasonal carbon sources and sinks

Author(s) Steinkamp, K., Gruber, N.
Publication Type Journal Items, Publication Status: Published
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Title A joint atmosphere-ocean inversion for the estimation of seasonal carbon sources and sinks
Author(s) Steinkamp, K.
Gruber, N.
Journal or Series Title Global biogeochemical cycles
Volume Number 27
Issue Number 3
Start Page 732
End Page 745
ISSN 0886-6236
1944-9224
Publisher American Geophysical Union
Publication Place Washington, DC
Publication Date 2013-09
Keyword(s) Atmospheric inversion
Carbon cycle
Carbon sinks and sources
Air-land flux
Joint inversion
Air-sea flux
Abstract We have estimated global surface fluxes of carbon dioxide for the period 1992-1996 using an inverse approach that sequentially considers four constraints: (1) atmospheric CO2, (2) ocean interior DIC (dissolved inorganic carbon) interpreted through an ocean interior inversion and surface ocean pCO(2) (partial pressure of CO2), (3) annual prior fluxes for selected land regions, and (4) atmospheric model selection based on vertical transport skill. Estimated fluxes are monthly resolved for each of the 22 Transcom regions over land and ocean. The ocean constraint is particularly valuable, as it does not only add prior information about air-sea fluxes to the inversion problem but also preserves the regional variance-covariance structure from the underlying ocean interior inversion. It allows to constrain annual oceanic uptake of 1.8 PgCyr(-1) to within 0.2 PgCyr(-1), which implies a net annual land uptake of 1.3 (0.3) PgCyr(-1). Furthermore, it leads to a pronounced asymmetry in the seasonal pattern of global land uptake, which was not seen in previous atmosphere-only inversions. Tropical land is consistently estimated to be a source of carbon, though the source magnitude is reduced as more constraints are applied. With all four constraints, the inversion suggests a net tropical source of 1.1 (0.9) PgCyr(-1), which is comparable to global estimates of deforestation rates in tropical forests and therefore implies an annually balanced tropical land biosphere flux. This balance is not found, however, at the regional level: For the Amazonian region and after accounting for deforestation, we find a biospheric source of 0.6 (0.5) PgCyr(-1). This is at the upper range of estimates from bottom-up methods, which tend to identify the region as a sink.
DOI 10.1002/gbc.20064
Additional Notes Published online by: Wiley
Received 11 June 2012, Revised 27 June 2013, Accepted 3 July 2013, Published online 18 August 2013
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03731
Organisational Unit(s)
NEBIS System Number 000041178
Source Database ID WOS-000325488600011
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@article{Stnkmp2013,
author = "Steinkamp, K. and Gruber, N.",
title = "{A} joint atmosphere-ocean inversion for the estimation of seasonal carbon sources and sinks",
journal = "Global biogeochemical cycles",
year = 2013,
volume = "27",
number = "3",
pages = "732--745",
month = sep,
}


E-Citations record created: Mon, 18 Nov 2013, 11:00:59 CET