On the Other Side of the Air/Sea Interface On the Other Side of the Air/Sea Interface A title conceived before I knew that Manuel and Corinne were also giving talks Andy Jacobson, Nicolas Gruber, Manuel Gloor, Jorge L. Sarmiento, Christopher L. Sabine, and Richard A. Feely 13 May 2003 TransCom meeting in Jena Special thanks to Robert M. Key and Kitack Lee for providing data.

Road Map Transient Footprints Anthropogenic Inversion Equlibrium Footprints Preindustrial Inversion Contemporary inversion, ∆pCO2, gas exchange Atmospheric Footprints Joint Inversion

Recent Carbon Survey Number of Observations ~ C* of Gruber, Sarmiento, and Stocker (1996) to estimate anthropogenic DIC. Innumerable data authors, but represented by Feely, Sabine, Lee, Key.

The C* Method The C* Method DICC* = DIC - ∆C bio Salinity (psu) Source: Gruber, Sarmiento, and Stocker (1996) GBC 10(4) ∆C ant ∆C gase x Dissolved Inorganic Carbon (DIC) and C* on AAIW Density Surface ∆C bio from soft-tissue (AOU or P) and carbonate (Alk) changes ∆C gasex = sC* - ∆C ant

Anthropogenic Carbon Inventory

Dye29 Regions Conformable to the 11 TransCom3 ocean regions; allows direct comparison

Dye Flux Patterns Takahashi et al.(2002) CO 2 flux pattern ( ∫∫dxdy = 1 ) daSilva et al. heat flux pattern ( ∫∫dxdy = 1 ) Eastern Tropical South Pacific Uniform Heat Flux CO 2 Flux “Forward” (OCMIP2 biotic) Spatial distribution of the unit flux within each region.

Sensitivity Analysis: Transport and Surface Flux Pattern OGCM Configuration Takahashi CO 2 flux pattern Uniform flux pattern Heat flux pattern “Forward” pattern Ai low, Kv low “LL”  Ai high, Kv high “HH”  Ai low, Kv high South “LHS”  ECMWF, ndp, 4pt salinity rest, Ai low, Kv med-HiS (2000m) “PSS”  Ai low, Kv med-HiS (2000m), 4pt salinity rest ”RDS” 

MOM3 Southern Ocean CFCs and Radiocarbon Observations “Standard”configuration Courtesty of Katsumi Matsumoto

Modeled Southern Ocean Anthropogenic CO 2 and Radiocarbon Courtesy of Katsumi Matsumoto Note: values not yet final

Modeled Southern Ocean CFCs and Radiocarbon Courtesy of Katsumi Matsumoto Note: values not yet final

Anthropogenic Basis Functions Anthropogenic Basis Functions : aggregated and vertically integrated MOM3 rds MOM3 pss Pacific Tropical (16-19) Pacific Subpolar (22-24)

Results for Anthropogenic Carbon Inversions First, the diagnostics--can we trust the inversions? 1.Simulations with synthetic data show that this inversion is very stable. Retrieved fluxes differ by O(10 -3 ) PgCyr -1 reg -1 from known “true” values. This is as expected from the small condition number of the A matrices, and is a manifestation of the uncorrelated footprints. 2. 2 looks pretty good. E.g., with DOFs (ratio 0.88) 3.Analysis of residuals is ongoing. Outliers are frightening.

Global Ocean Uptake of Anthropogenic CO 2 PgC/yr into Ocean, in 1995 OGCM Configuration Takahashi CO 2 flux pattern Uniform flux pattern Heat flux pattern “Forward” pattern Ai low, Kv low “LL” Ai high, Kv high “HH” Ai low, Kv high South “LHS” ECMWF, ndp, 4pt salinity rest, Ai low, Kv med-HiS (2000m) “PSS” Ai low, Kv med-HiS (2000m), 4pt salinity rest ”RDS” Across-model Mean Sink: 2.2 ± 0.3 PgC/yr (1995)

Ocean Sink Estimates (after LeQuéré et al., 2003)

Recent Decades (after LeQuéré et al., 2003) New inversion estimates: 1985: -1.7 ± : -1.9 ± : -2.2 ± : -2.5 ± 0.3 Uncertainties for current results are two standard deviations across all 14 model runs. Current Estimate

LLHH PSSRDS Circulation Sensitivity Anthropogenic Carbon Flux into Ocean (mol C m -2 yr -1, for “forward” pattern)

Simple Pycnocline Depth Model equatorial upwelling NADWformation dense water light water D NorthSouthEquator Pycnocline depth D sets the NADW formation rate. Our models are all configured to have about the same pycnocline depth. Return flow is a via diffuse equatorial upwelling, and thus a condition is set upon the magnitude of vertical diffusivity Kv.

Gnanadesikan (1999) Return flow is a balance of upwelling both at the equator and in the Southern Ocean. This balance is set by along-isopycnal diffusivity Ai and vertical diffusivity Kv. Recall that pycnocline depth--and thus NADW formation rate--is held (nearly) constant equatorial upwelling NADWformation SouthernOceanupwelling dense water light water D NorthSouthEquator

Watermass Transformation Rates Circulation Model Southern Ocean Upwelling (Sv) Equatorial Upwelling (Sv) NADW Formation (Sv) Ai low, Kv low “LL” Ai high, Kv high “HH” Ai low, Kv high South “LHS” ECMWF, ndp, 4pt salinity rest, Ai low, Kv med- HiS (2000m) “PSS” Ai low, Kv med- HiS (2000m), 4pt salinity rest ”RDS” Pathway of Return Flow Transformation rates diagnosed from models by analyzing the meridional transport of light (  0 < 27.4) waters.

LL LHS HH PSS RDS Uni Heat Tak Fwd Global Anthropogenic Carbon Flux vs. NADW Formation Rate NADW Formation Rate NADW Formation Rate (Sv) Anthro Flux (PgC/yr) Transport sensitivity:range of 0.4 PgC/yr Pattern sensitivity:range of 0.08 PgC/yr

Southern Ocean Low Latitudes LL LHS HH PSS RDS Uni Heat Tak Fwd Regional Fluxes vs. Regional Transformation Rates

Inter-Pentadal Variability? DO NOT CITE This interpretation, while inconsistent with prior assumptions, suggests that an interpentadal signal is present in the data.

Forward and Inverse Anthropogenic DIC Same five models in all cases

Preindustrial Inversion Evidence for Seasonal Rectifier

DYE29_LL RECT29_LL Preindustrial Carbon Flux Inversions

Zonally-Integrated Preindustrial Flux Preindustrial Flux (mol C deg -1 yr -1 ) DYE29 unregularized Gloor 13 region

Zonally-Integrated Preindustrial Flux Preindustrial Flux (mol C deg -1 yr -1 ) DYE29 unregularized Gloor 13 region DYE29 SVD: 23 retained DYE29 SVD: 15 retained

Zonally-Integrated Preindustrial Flux Preindustrial Flux (mol C deg -1 yr -1 ) DYE29 unregularized Gloor 13 region DYE29 SVD: 23 retained DYE29 SVD: 15 retained DYE29 aggregated to Gloor regions (22)

Covariate Data Errors Recall cost function: Biases manifested as off- diagonal covariances in C. N.B.  ij =  ji and  ii =  i 2. Multivariate normal PDF Minimizing J still maximizes the likelihood (but you have to do it numerically).

Ongoing Projects Characterization of C* biases (Sarah Fletcher, Andy) Transport sensitivity: OCMIP group to produce Green’s functions (Sarah Fletcher). Also use MOM4 and HIM at Princeton. Time-dependent anthropogenic inverse, possibly with bomb radiocarbon and CFC constraints (Andy) Can our estimates tell us anything about gas exchange parameterizations? (Andy, Manuel) Joint atmosphere-ocean inverse.

fin