Interannual variations in continental‐scale net carbon exchange and sensitivity to observing networks estimated from atmospheric CO2 inversions for the period 1980 to 2005

[1] Interannually varying net carbon exchange fluxes from the TransCom 3 Level 2 Atmospheric Inversion Intercomparison Experiment are presented for the 1980 to 2005 time period. The fluxes represent the model mean, net carbon exchange for 11 land and 11 ocean regions after subtraction of fossil fuel CO2 emissions. Both aggregated regional totals and the individual regional estimates are accompanied by a model uncertainty and model spread. We find that interannual variability is larger on the land than the ocean, with total land exchange correlated to the timing of both El Nino/Southern Oscillation (ENSO) as well as the eruption of Mt. Pinatubo. The post-Pinatubo negative flux anomaly is evident across much of the tropical and northern extratropical land regions. In the oceans, the tropics tend to exhibit the greatest level of interannual variability, while on land, the interannual variability is slightly greater in the tropics and northern extratropics. The interannual variation in carbon flux estimates aggregated by land and ocean across latitudinal bands remains consistent across eight different CO2 observing networks. The interannual variation in carbon flux estimates for individual flux regions remains mostly consistent across the individual observing networks. At all scales, there is considerable consistency in the interannual variations among the 13 participating model groups. Finally, consistent with other studies using different techniques, we find a considerable positive net carbon flux anomaly in the tropical land during the period of the large ENSO in 1997/1998 which is evident in the Tropical Asia, Temperate Asia, Northern African, and Southern Africa land regions. Negative anomalies are estimated for the East Pacific Ocean and South Pacific Ocean regions. Earlier ENSO events of the 1980s are most evident in southern land positive flux anomalies.

[1]  Taro Takahashi,et al.  Net sea-air CO2 flux over the global oceans: An improved estimate based on the sea-air pCO2 difference , 1999 .

[2]  R. Schnur,et al.  Climate-carbon cycle feedback analysis: Results from the C , 2006 .

[3]  E. Matthews,et al.  Geographic patterns of carbon dioxide emissions from fossil-fuel burning, hydraulic cement production, and gas flaring on a one degree by one degree grid cell basis: 1950 to 1990 , 1997 .

[4]  Time-dependent atmospheric CO2 inversions based on interannually varying tracer transport , 2003 .

[5]  R. Giering,et al.  Two decades of terrestrial carbon fluxes from a carbon cycle data assimilation system (CCDAS) , 2005 .

[6]  Corinne Le Quéré,et al.  Regional changes in carbon dioxide fluxes of land and oceans since 1980. , 2000, Science.

[7]  Gregg Marland,et al.  A 1° × 1° distribution of carbon dioxide emissions from fossil fuel consumption and cement manufacture, 1950–1990 , 1996 .

[8]  Shamil Maksyutov,et al.  TransCom 3 CO2 inversion intercomparison: 1. Annual mean control results and sensitivity to transport and prior flux information , 2003 .

[9]  Ian G. Enting,et al.  Reconstructing the recent carbon cycle from atmospheric CO2, δ13C and O2/N2 observations* , 1999 .

[10]  Ian G. Enting,et al.  A synthesis inversion of the concentration and δ 13 C of atmospheric CO 2 , 1995 .

[11]  P. Ciais,et al.  Multiple constraints on regional CO2 flux variations over land and oceans , 2005 .

[12]  Ian G. Enting,et al.  Inverse problems in atmospheric constituent transport , 2002 .

[13]  R. Betts,et al.  Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model , 2000, Nature.

[14]  R. Francey,et al.  Interannual growth rate variations of atmospheric CO2 and its δ13C, H2, CH4, and CO between 1992 and 1999 linked to biomass burning , 2002 .

[15]  K. Wolter,et al.  Measuring the strength of ENSO events: How does 1997/98 rank? , 1998 .

[16]  Taro Takahashi,et al.  Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models , 2002, Nature.

[17]  Philippe Ciais,et al.  Weak Northern and Strong Tropical Land Carbon Uptake from Vertical Profiles of Atmospheric CO2 , 2007, Science.

[18]  Robert J. Scholes,et al.  The Carbon Cycle and Atmospheric Carbon Dioxide , 2001 .

[19]  R. Dargaville,et al.  The relationship between tropical CO2 fluxes and the El Niño‐Southern Oscillation , 1999 .

[20]  Michael L. Roderick,et al.  Pinatubo, Diffuse Light, and the Carbon Cycle , 2003, Science.

[21]  Dennis D. Baldocchi,et al.  Response of a Deciduous Forest to the Mount Pinatubo Eruption: Enhanced Photosynthesis , 2003, Science.

[22]  Thomas Kaminski,et al.  On aggregation errors in atmospheric transport inversions , 2001 .

[23]  S. Page,et al.  The amount of carbon released from peat and forest fires in Indonesia during 1997 , 2002, Nature.

[24]  Gregg Marland,et al.  Carbon Dioxide Emission Estimates from Fossil-Fuel Burning\, Hydraulic Cement Production\, and Gas Flaring for 1995 on a One Degree Grid Cell Basis , 2003 .

[25]  Gloor,et al.  A Large Terrestrial Carbon Sink in North America Implied by Atmospheric and Oceanic Carbon Dioxide Data and Models , 2022 .

[26]  Kevin E. Trenberth,et al.  Indices of El Niño Evolution , 2001 .

[27]  Shamil Maksyutov,et al.  Role of biomass burning and climate anomalies for land‐atmosphere carbon fluxes based on inverse modeling of atmospheric CO2 , 2005, Global Biogeochemical Cycles.

[28]  Shamil Maksyutov,et al.  Sensitivity of inverse estimation of annual mean CO2 sources and sinks to ocean‐only sites versus all‐sites observational networks , 2006, Geophysical Research Letters.

[29]  J. Randerson,et al.  Interannual variability in global biomass burning emissions from 1997 to 2004 , 2006 .

[30]  R. Bacastow,et al.  Modulation of atmospheric carbon dioxide by the Southern Oscillation , 1976, Nature.

[31]  Jacqueline Boutin,et al.  Seasonal and interannual variability of CO2 in the equatorial Pacific , 2002 .

[32]  M. Roderick,et al.  Atmospheric science. Pinatubo, diffuse light, and the carbon cycle. , 2003, Science.

[33]  Kevin R. Gurney,et al.  TransCom 3 inversion intercomparison: Impact of transport model errors on the interannual variability of regional CO2 fluxes, 1988–2003 , 2006 .

[34]  Christopher B. Field,et al.  The contribution of terrestrial sources and sinks to trends in the seasonal cycle of atmospheric carbon dioxide , 1997 .

[35]  I. Fung,et al.  CO2 seasonality indicates origins of post‐Pinatubo sink , 2004 .

[36]  Kevin R. Gurney,et al.  On error estimation in atmospheric CO2 inversions , 2002 .

[37]  Kevin R. Gurney,et al.  TransCom 3 CO2 inversion intercomparison: 2. Sensitivity of annual mean results to data choices , 2003 .

[38]  Philippe Ciais,et al.  Transcom 3 inversion intercomparison: Model mean results for the estimation of seasonal carbon sources and sinks , 2004, Global Biogeochemical Cycles.

[39]  David Schimel,et al.  Carbon cycle: The wildfire factor , 2002, Nature.

[40]  Sander Houweling,et al.  CO 2 flux history 1982–2001 inferred from atmospheric data using a global inversion of atmospheric transport , 2003 .

[41]  Shamil Maksyutov,et al.  Sensitivity of optimal extension of CO2 observation networks to model transport , 2003 .

[42]  Kevin R. Gurney,et al.  Sensitivity of atmospheric CO2 inversions to seasonal and interannual variations in fossil fuel emissions , 2005 .

[43]  R. Dargaville,et al.  Implications of interannual variability in atmospheric circulation on modeled CO2 concentrations and source estimates , 2000 .

[44]  M. Wahlen,et al.  Interannual extremes in the rate of rise of atmospheric carbon dioxide since 1980 , 1995, Nature.