# Presentation: 174002

##    CLIVAR/CO2 Repeat Hydrography 

**   ****CLIVAR/CO****2**** Repeat Hydrography **

- R.A. Feely, C.L. Sabine, R. Wanninkhof, G.C. Johnson, J.L. Bullister, M. Barringer, C.W. Mordy, J.-Z. Zhang, M.F. Lamb, D. Greeley, F.J. Millero,
- A.G. Dickson,  Nicolas Gruber, Robert H. Byrne and Aleck Wang

**Goal:**

**Approach:**

- http://ushydro.ucsd.edu/

**Achievements:**

- The U.S. CLIVAR/CO2 Repeat Hydrography Program has completed 6 of 19 cruises and is on schedule.

- The sequence and timing of the CLIVAR/CO2 Repeat Hydrography cruises have been selected so that there is roughly a decade between them and the WOCE/JGOFS global survey.

- To quantify decadal changes in the inventory and transport of heat, fresh water,  carbon dioxide (CO2), chlorofluorocarbon tracers and related parameters in the oceans.

- Global map of planned CLIVAR/CO2 Repeat
- Hydrography Program hydrographic sections

## Outline:

**COP Annual Review 25-27 May 2005**

-  Describe changes in DIC and AOU discuss implications.

-  Provide an estimate of changes in inorganic carbon and
-     anthropogenic carbon uptake and uncertainties therein.

-  Discuss implications for future planning.

-  Present an overview changes in inorganic carbon (DIC)
-     and related physical (CFC-12) and biogeochemical
-     parameters (AOU and NO3) in the  Atlantic and Pacific.

## Concerns about how to obtain the decadal signal of anthropogenic CO2 in the ocean?

**Concerns about how to obtain the decadal signal of anthropogenic CO****2**** in the ocean?**
**∆****DIC = ∆ C****anthro**** + Intrinsic changes + Climate induced changes**
**Intrinsic and climate induced changes can be about the same order of magnitude as ∆ C****anthro.**
**Decrease in  ventilation in upper thermocline of high and mid-latitude waters in N-Atlantic and North Pacific resulting in generally greater AOU and NO****3**** levels.**
**Redfield stoichiometry is not always applicable since some of O****2**** changes are caused by changes in ventilation.  **
**Conventional analytical approaches to determine ∆ C****anthro**** can be problematic and assumption in  methods should be investigated and supported with modeling efforts.**
**Need for higher resolution data in some regions.**

**COP Annual Review 25-27 May 2005**

## WOCE/JGOFS/OACES Global CO2 Survey

**WOCE/JGOFS/OACES Global CO****2**** Survey**

**~72,000 sample locations **
**collected in the 1990s**

**DIC ± 2 μmol kg****-1**
**TA ± 4 μmol kg****-1**

- Sabine et al (2004).

- Mapped Inventory = 106±17 Pg C

- + marginal seas = 6± 6 Pg C

- + Arctic Ocean = 6± 6 Pg C

- Total Inventory = 118±19 Pg C

## We must understand the temporal and spatial changes of the global ocean carbon system and the feedbacks to the climate system. 

- We must understand the temporal and spatial changes of the global ocean carbon system and the feedbacks to the climate system.

*CLIVAR/CO**2** Repeat Hydrography Program*

## Water Mass Formation Regions

- Anthropogenic CO2 moves into the ocean interior with mode, intermediate, deep and bottom water.

- The highest inventories are found in areas where water is sinking into the ocean interior taking with it the anthropogenic CO2 accumulated at the surface.

## Figure supplied by Curtis Deutsch

## 	              11.6  μmol/kg (A16N decade)

- Expected changes in surface ocean due to increased atmospheric burden:
- 	              11.6  μmol/kg (A16N decade)
- (18.6/11.88 ppm CO2 Mauna Loa; Revelle Factor  = 9.7; DIC = 2059; pCO2(20) = 347; T =20.8)

*Atmospheric CO**2** increase*

*Equilibrium surface water CO**2** increase*

## A16N:

**A16N:**
- 1988: OC202-AOU, CFC-12
- 1993: NA93-DIC
- 2003: A16N-AOU, CFC-12, DIC
**A16S:**
- 1989: HYDROS4- AOU, CFC-12, DIC
- 1989: Save5- AOU, CFC-12, DIC
- 2005: A16S- AOU, CFC-12, DIC
**A22:**
- August-September 1997
- October-November 2003
**A20:**
- July-August 1997
- August-September 2003

## High-resolution tracers in 

- excellent precision
- pCFC: ± 0.005 pmol kg-1
- AOU: ± 1-2 μmol kg-1
-  DIC: ± 1-2 μmol kg-1

**High-resolution tracers in **
**the Atlantic Ocean**

## Decadal changes in 

- regions in the upper thermocline with:
- CFC-12 changes > 0.9 pmol kg-1
- AOU changes > 20 μmol kg-1
-  DIC changes > 30 μmol kg-1
- Greater than expected changes due to:
-  Movement of fronts/eddies
-      watermasses
-  Changes in ventilation
-  Changes in remineralization

**Decadal changes in **
**the Atlantic Ocean**

## A16N upper thermocline: 26.8- 27.4 

-  *∆**DIC = ∆ C**anthro** ****+ Intrinsic changes + Climate changes***

**A16N upper thermocline: 26.8- 27.4**

- If a canonical RN:O stoichiometry holds, remineralization cannot solely account for changes in AOU

- ∆ AOU

- ∆  NO3

-  O2/NO3

- Greater O2 change

- Greater NO3 change

- NO3/ O2 ≈ 16/170 = 0.094

## A16N upper thermocline: 26.8- 27.4

- Multiparameter Linear Regression (MLR) technique >15  ̊N
- 	 DIC(1993) = a1 + b1 T + c1 S + d1 AOU +  e1 NO3
- 	 DIC(2003) = a2 + b2 T + c2 S + d2 AOU +  e2 NO3
- 	*n≈3000, r**2** ≈ 0.98, standard error DIC ≈ 5 μmol/kg*
- E-MLR:	∆DIC (2003-1993) = a2-1 + b2-1 T + c2-1 S + d2-1 AOU +  e2-1 NO3
- 			           = Canthro  (using  2003 T, S, AOU, NO3 data)

**A16N upper thermocline: 26.8- 27.4**

## Specific inventories A16N (> 15  ̊N):

**Specific inventories A16N (> 15  ̊N):**
-  Large spatial variations in ∆DIC
-  Overcorrection using AOU
-  MLR- no  bottom water residual

- Bin-averaged depth plots with smoothed curve

## Higher throughput 

**Using USF Seas Technology**

**Robert H. Byrne and Aleck Wang, USF**

## WOCE/JGOFS Global CO2 Survey

- WOCE/JGOFS Global CO2 Survey

- Portion of P16 covered by this cruise includes:
- P16S/P17S – August 1991
- P16A/P17A – October 1992
- S4P – March 1992

## SAF

- ACCF

## SAF

- ACCF

## WOCE/JGOFS Global CO2 Survey

- WOCE/JGOFS Global CO2 Survey

- P2 Repeat cruise dates:
- P2 – July-August 1994
- P2 – July-August 2004

## MLR Procedure

**North Pacific DIC Changes (2004 - 1994)**

- Large positive DIC differences in surface waters and 10 - 37 μmol/kg increases at intermediate depths between 200 - 800m.

**COP Annual Review 25-27 May 2005**

- _MLR Procedure_

## ∆CANTH

- ∆**C****ANTH**

- 2004 - 1994 P2 Repeat Hydrographic Section Difference

**COP Annual Review 25-27 May 2005**

- ∆CANTH = ∆CMEAS  - ∆CORG - ∆CTALK

## ∆CORG

- ∆CORG

- 2004 - 1994 P2 Repeat Hydrographic Section Difference

**COP Annual Review 25-27 May 2005**

- ∆CORG = (117/170) * (AOU2004 - AOUCALC(MLR1994))

- RC/O = 0.688 from Anderson and Sarmiento (1994)

## ∆CTALK

- ∆**C****TALK**

- 2004 - 1994 P2 Repeat Hydrographic Section Difference

**COP Annual Review 25-27 May 2005**

- ∆CTALK =  0.5 * (TALKMEAS – TALKCALC(MLR1994))

## CO2 Growth Rate on Isopycnal Surfaces along 30°N

**CO****2**** Growth Rate on Isopycnal Surfaces along 30°N**
**      ****Based on P2 2004 - 1994 Comparison**

## Carbon Increases in the Pacific and Atlantic Oceans

**Carbon Increases in the Pacific and Atlantic Oceans**

**COP Annual Review 25-27 May 2005**

| Integrated uptakerate (mol m2 yr-1) | Mixed layer uptake(μmol kg-1 yr-1) | pCO2 increase (μatm yr-1) | Approach
 | Area of Study | Years | Depth Range
(m) | Reference |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 0.7 ± 0.2 | -- | -- | MLR | North Atlantic | 1993-2003 | 0-5000 | This work |
| -- | -- | -- | -- | South Atlantic | 1989-2005 | 0-5000 | This Work |
| 1.0 ± 0.6 | O.6± 0.4 | 1.2 ± 0.5 | MLR, Obs | North Pacific | 1973-2004 | 0-1200 | Sabine et al., (2004); Takahashi
et al., (in prep)
 |
| -- | -- | -- | MLR, Obs | South Pacific | 1993-2005 | 0-5000 | This Work |

## Deutsch and Thompson: O2 changes (relative to 1960’s)

- Deutsch and Thompson: O2 changes (relative to 1960’s)

## Causes of oxygen change (1990’s-1980’s) 26.6 

- Causes of oxygen change (1990’s-1980’s) 26.6* *

*a)*

*b)*

*c)*

*d)*

## Conclusions

_**Conclusions**_

**Air-sea exchange, ventilation, and circulation processes are the**
**      ****primary control of the DIC increases in the surface and **
**      ****intermediate waters of the Atlantic and Pacific Oceans. **

**We have observed mixed layer and intermediate water DIC **
**      ****increases ranging from 0.4 - 2.2  μmol kg****-1**** yr****-1**** over the past **
**      ****decade, with significant regional differences.**

**Changes in circulation cause significant decadal changes in DIC,**
**      ****but we must be able to distinguish natural process from climate **
**      ****change effects.**

**COP Annual Review 25-27 May 2005**

## Recommendations

_**Recommendations**_

**Increase Repeat Hydrography sample coverage in regions **
**      ****where active ventilation is occurring.**

**Test new methods for high-resolution O****2**** and CO****2**** profiling on **
**	****Repeat Hydrography cruises. Provide support for profiling**
**      ****O****2**** and CO****2**** measurements.**

**Develop basin-scale carbon models that accurately reproduce **
**      ****gas exchange, ventilation and biogeochemical processes.**

**COP Annual Review 25-27 May 2005**

**4.   Support international efforts for data synthesis and exchange.**

##   Onto our Next Cruise - P16N in 2006!

-   Onto our Next Cruise - P16N in 2006!

**Notes:**
As Lisa mentioned earlier The major goal of the NOAA Carbon Cycle program is to:

Improve our ability to predict the fate of anthropogenic CO2 and future atmospheric CO2 concentrations, using a combination of global observations, process-oriented field studies, and modeling