1. fCO 2 in the Ecuatorial and North Subtropical Atlantic X.A. Padin, Marcos Vázquez-Rodríguez, Fiz F. Pérez, Aida F.Ríos CSIC, Instituto de Investigaciones Marinas. c/Eduardo Cabello, 6. 36208-Vigo, Spain.

2.  OBJECTIVES Evaluation of air-sea CO 2 fluxes throughout meridional transects  MATERIAL Underway measurements were performed on board BIO Hespérides and BIO Las Palmas  SAMPLING PERIOD Nine cruises conducted from 2000 to 2006 Spring cruises: 3 Autumn cruises: 6 FICARAM Spring Cruises Autumn Cruises

3. 1 North Subtropical Gyre ∆f CO 2 sw Autumn 2 North Equatorial Current 3 Equatorial Region 4 Brazil Current

4. Empirical algorithms were developed using the following… fCO 2 fCO 2 @25 ºC 2000 fCO 2 @25 ºC 2000 = fCO 2 @25 ºC 2000.0 + a Lon + b Lat + +c (SST-25) + d (SST-25) 2 + e (SST-25) 3 + f (SSS-35) + g (SSS-35) 2 + h (SSS-35) 3 modeled fCO 2 modeled fCO 2 @25 ºC 2000 Normalization to 25ºC [Takahashi et al., 2003] Normalization to year 2000 (1.4 µatm yr -1 ) Conversion to in situ SST [Takahashi et al., 2003] Conversion to the year of measurement (1.4 µatm yr -1 )

5. fCO 2 @25º 2000 ±8 = 455 + f( SST 1: 3,SSS 1: 3, Lon, Lat) n=9513, r 2 =0.89 North Subtropical Gyre [17º N - 35º N]

6. North Equatorial Current [5º N - 17º N] fCO 2 @25º 2000 ±12 = 288 + f( SST 1: 3,SSS 1: 3, Lon, Lat) n=5851, r 2 =0.80

7. Equatorial Region [5º S - 5º N] fCO2@25º 2000 ±5 = 341 + f(SST 1:3,SSS 1:3, Lon, Lat) n=4495, r 2 =0.94

8. Brazil Current [10º S - 5º S] fCO 2 @25º 2000 ±11 = 503 + f( SST 1: 3,SSS 1: 3, Lon, Lat) n=2416, r 2 =0.67

9. -2±8 µatm n=2880 ; r 2 =0.76 Modeled vs. Observed fCO 2 along FICARAM 5

10. North Subtropical Gyre [17º N - 35º N] -0.2±0.2 mol C m -2 yr -1 n=7 ; r 2 =0.99

11. North Equatorial Current [5º N - 17º N] -0.3±0.2 mol C m -2 yr -1 n=7 ; r 2 =0.93

12. Equatorial Region [5º S - 5º N] 0.1±0.2 mol C m -2 yr -1 n=7 ; r 2 =0.79

13. Brazil Current [10º S - 5º S] -0.1±0.1 mol C m -2 yr -1 n=7 ; r 2 =0.98

14. Empirical algorithms were built to model the fCO 2 in the Equator and North Subtropical Atlantic using 9 FICARAM cruises. The zone was divided in 4 regions well characterized: - Northern Subtropical Gyre (r 2 =0.99; rms=0.2 molC·m -2 ·yr -1 ) - Northern Equatorial Current (r 2 =0.93; rms=0.3 molC·m -2 ·yr -1 ) - Equatorial Region (r 2 =0.79; rms=0.2 molC·m -2 ·yr -1 ) - Brazil Current (r 2 =0.98; rms=0.1 molC·m -2 ·yr -1 ) SUMMARY

15. Integration of other cruises to increase the spatial and temporal coverage. Produce a climatology of fCO 2 in the Equatorial and North Subtropical Atlantic Comparison with recent Takahashi’s climatology. FUTURE WORK