Commentary to Richard Lampitt:Commentary to Richard Lampitt:

‘‘Linking Surface Ocean Linking Surface Ocean and the Deep Sea’and the Deep Sea’

Susanne NeuerSusanne Neuer

Differences in the biological Differences in the biological carbon pump within the carbon pump within the same biogeographical same biogeographical provinceprovince

A case study from the A case study from the subtropical North Atlantic subtropical North Atlantic GyreGyre

NAST(E)NAST(W)

The North Atlantic The North Atlantic Subtropical GyralSubtropical GyralProvince (NAST)Province (NAST)

East:ESTOC (European Station for Time-Series, Canary Islands)

West:

BATS (Bermuda Atlantic Time-Series)Data sets used for this study have been obtained Data sets used for this study have been obtained

simultaneously during 1996-1998.simultaneously during 1996-1998.

0.2

0.4

0.6

0.8

1.0

Pri

ma

ry P

rod

uc

tio

n

( g

m-2 d

-1 )

0.0

0.2

0.4

Su

rfa

ce

ch

loro

ph

yll

( m

g m

-3 )

A

B

1996 1997 1998

Jan Apr Jul O ct Jan Apr Jul O ct Jan Apr Jul O ct

0

20

40

60

E-P

OC

(m

g m

-2d

-1)

E S TO C M TE S TO C S TB A TS

Seasonality of surface chlorophyll, integrated primary productionand export production at ESTOC and BATS

Chl a

PP

Epoc

Neuer et al.2002

Yearly integrated PP, E POC and

ER (EPoc /PP) for ESTOC and BATS

     PP

mol C m-2 yr-1

E POC

mol C m-2 yr-1

ER

  BATS ESTOC BATS ESTOCa BATS ESTOCb

1996 16.3 11.9 1.4 0.24 / 0.16 0.086 0.017

1997 13.3 12.0 1.3 0.16 / 0.16 0.098 0.013

1998 13.9 11.7 0.7 -- / 0.20 0.050 0.017

AVG 14.5 11.9 1.1 0.2 0.08 0.016aShallow moored/surface tethered trap. Surface tethered trap value of 1996 and 1997

composite of both years b Mean of moored and surface tethered traps. 

Neuer et al.2002

ESTOCBATS

200

100

0

Mix

ed L

ayer

Dep

th (

m)

0

200

400 Nitrate-N

(µmo

l m-2 )

1996 1997 1998

Mixed layer depth and Nitrate-N input at ESTOC and BATS

ESTOC: 0.06 - 0.2 mmol N/m2/yr

BATS: 0.01 - 0.5 mmol N/m2/yrNeuer et al.2002

BATS ESTOC

New Production

(mol N m-2yr-1)

0.63 0.04

Convection 0.37 0.00

Vertical diffusion 0.10 0.02

Vertical advection 0.12 0.02

Horizontal advection 0.04 0.00

Horizontal diffusion 0.00 0.00

Vertical velocity( m yr-1 )

-31 -30

Nutrient budgets at BATS and ESTOC diagnosed from an eddy-resolving 0.1 degree resolution simulation of the North Atlantic (after McGillicuddy et al. in press)

Snapshots of temperature and new production in a 0.1 degree resolution simulation of the North Atlantic

(McGillicuddy et al., GBC, in press)

ConclusionsConclusions

ESTOC (NAST-E) has comparable ESTOC (NAST-E) has comparable surface chlorophyll and primary surface chlorophyll and primary production than BATS (NAST-W), production than BATS (NAST-W), but new (export) production is but new (export) production is significantly lower.significantly lower.

ConclusionsConclusions

Lower input of new nutrients does Lower input of new nutrients does not necessarily result in lower PP not necessarily result in lower PP per se but influences the removal per se but influences the removal efficiency (export ratio) of efficiency (export ratio) of biologically produced carbon into biologically produced carbon into the ocean’s interior.the ocean’s interior.

ConclusionsConclusions

Primary production and surface Primary production and surface chlorophyll alone are insufficient chlorophyll alone are insufficient to constrain the amount of carbon to constrain the amount of carbon export in the subtropical ocean.export in the subtropical ocean.

ReferencesReferences

Neuer, S., R. Davenport, T. Freudenthal, G. WeferNeuer, S., R. Davenport, T. Freudenthal, G. Wefer , O. Llinás, , O. Llinás, M-J. Rueda, D. K. Steinberg andM-J. Rueda, D. K. Steinberg and D.D. Karl. 2002. Differences in Karl. 2002. Differences in the biological carbon pump at three subtropical ocean sites. the biological carbon pump at three subtropical ocean sites. Geophys. Res. LettGeophys. Res. Lett., 29, 32-1 to 32-4.., 29, 32-1 to 32-4.

McGillicuddy, D.J., Anderson, L.A., Doney, S.C., and M.E. McGillicuddy, D.J., Anderson, L.A., Doney, S.C., and M.E. Maltrud. Eddy-driven sources and sinks of nutrients in the Maltrud. Eddy-driven sources and sinks of nutrients in the upper ocean: results from a 0.1 degree resolution model of the upper ocean: results from a 0.1 degree resolution model of the North Atlantic. In press, North Atlantic. In press, Global Biogeochemical CyclesGlobal Biogeochemical Cycles..