Global trends in air-sea CO 2 fluxes based on in situ and satellite products Rik Wanninkhof, NOAA/AOML ACE Ocean Productivity and Carbon Cycle (OPCC) Workshop.

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Global trends in air-sea CO 2 fluxes based on in situ and satellite products Rik Wanninkhof, NOAA/AOML ACE Ocean Productivity and Carbon Cycle (OPCC) Workshop - June 6-8,UC Santa Barbara Slide 2 Sea surface temperature (SST) Wind speed CCMP (Cross-Calibrated Multi-Platform wind product) [Atlas et al., 2011] Sea-air CO 2 Flux = K 0 k pCO 2 [Takahashi et al., 2009] OPCC OPCC Global Ocean Sea-Air CO 2 Fluxes Methods: pCO 2 climatology k 660 = 0.251 Slide 3 Wind k pCO 2 Air-Sea CO 2 Flux SST Transport Biology Wind Waves Bubbles Surface Film Near Surface Turbulence Bock et al. (1999) OPCC OPCC Global Ocean Sea-Air CO 2 Fluxes Factors influencing CO 2 flux estimates Slide 4 OPCC OPCC Global Ocean Sea-Air CO 2 Fluxes Data coverage T-09 climatology Slide 5 A Multi-national Effort: England USA France Netherlands Germany Spain China Japan Tasmania Norway And more Complete Data Set: 19682008 10M points Our contribution: 3M points OPCC OPCC Global Ocean Sea-Air CO 2 Fluxes Surface Ocean Carbon Atlas (SOCAT) Slide 6 OPCC OPCC Global Ocean Sea-Air CO 2 Fluxes Remote sensing Wind: CCMP 6-hr k 660 = 0.251 based on global 14 C constraint Gas transfer velocity Slide 7 OPCC Global Ocean Sea-Air CO 2 Fluxes Global 14 C constraint Broecker and Peng (1994) Transfer velocity k av = 17.5 cm/hr u 2 = 69.3 (m/s) 2 u mean 7.4 m/s Semi-infinite Half space Bomb 14 C inventory constraint Globally: a = Constant Slide 8 OPCC Global Ocean Sea-Air CO 2 Fluxes Relationship of k and U 10 Good agreement with global bomb 14 C constraint and local studies Ho et al. 2011 Slide 9 Uncertainty in different components of the flux estimate (adapted from section 6, T- 09) Takahashi et al. (2009)RECCAP (2011) Pg C yr -1 %Pg C yr- 1 %Pg C yr- 1 Net flux-1.4-1.2 pCO 2 0.18 13%0.18 k 0.42 30%0.2 Wind (U)0.28 20%0.2 a 0.5 35%0.5 Total0.7 53%. 0.6 Under-sampling bias-0.2-0.2 Pre-industrial sea-air flux 0.4 0.2 0.4 0.2 Anthropogenic CO 2 flux-2.0 1.0-1.8 0.8 OPPC OPPC Sea-Air CO 2 Fluxes Climatological Magnitude and Uncertainty Slide 10 Temperature (C)-2 30 ( ln pCO 2 / T) = 0.0423 o C -1 400% VariableRangeRelationEffect TCO 2 ( mol kg -1 )1900-2200 ( ln pCO 2 / Tln TCO 2 ) = 10 400% Alkalinity( mol kg -1 )*2150-2350 ( ln pCO 2 / Tln TALK) = -9.4 -200% Salinity( mol kg -1 )*33.5-37 ( ln pCO 2 / Tln S) = 0.94 ~10% *Alkalinity and salinity are proportional and can be accounted for OPCC Global Ocean Sea-Air CO 2 Fluxes Factors influencing surface water pCO 2 Slide 11 Annual uptake of anthropogenic CO 2 since 1960 from models. The absolute uptake (solid line, left axis) has increased over time while the fraction of uptake (=ocean uptake/fossil fuel CO 2 release *100) (dashed line, right axis) has decreased. Data are obtained from http://lgmacweb.env.uea.ac.uk/lequere/co2/carbon_budget.htm (Le Qur et al., 2009). OPPC OPPC Sea-Air CO 2 Fluxes: Model and atm. based estimates of trends Slide 12 OPCC OPCC Sea-Air CO 2 : Flux variability Trends F ym = k ym K 0 ym {[pCO 2 2000m + (pCO 2SW / SST) 2000m SST ym 2000m ] }, (pCO 2SW / SST) 2000m : Optimal subannual relationships for each 4 by 5 grid box Park et al. Tellus B 2010:Variability of global net sea-air CO 2 fluxes over the last three decades using empirical relationships Slide 13 The linear regressions (solid line) for the flux are 0.009 0.005 Pg C yr -1, respectively. The 20-years mean values for the flux is -1.12 0.13 Pg C, respectively. Decrease in uptake due to winds and SST feedbacks OPCC OPCC Sea-Air CO 2 Fluxes Trends 1980-1999 Sea-air CO 2 Flux = K 0 k pCO 2 Slide 14 OPCC OPCC Global Ocean Sea-Air CO 2 Fluxes Remote sensing How can we quantify the impact of [remotely measured] biological processes on pCO 2 ? Regional approach Multi-sensor Melding in situ and remotely sensed information Slide 15 Annual uptake of anthropogenic CO 2 since 1960 from models. The absolute uptake (solid line, left axis) has increased over time while the fraction of uptake (=ocean uptake/fossil fuel CO 2 release *100) (dashed line, right axis) has decreased. Data are obtained from http://lgmacweb.env.uea.ac.uk/lequere/co2/carbon_budget.htm (Le Qur et al., 2009). OPCC OPCC Sea-Air CO 2 Fluxes: IPCC estimates Slide 16 Figure 4. Zonal wind comparison of several global wind products for the year 2000. The differences of up to 2 m/s are observed but the biases are not always consistent between high and low latitudes. (Figure courtesy of C. Sweeney).CCMP = Cross Calibrated Multi- Platform winds (Atlas et al., 2011); ECWMF =European Center for Medium Weather Forecasting; NCEP = National Center for Environmental Prediction; QSCAT = QuikSCAT polar orbiting satellite with an 1800 km wide measurement swath on the earth's surface equipped with the microwave scatterometer SeaWinds OPCC OPCC Sea-Air CO 2 : Global Winds