ModelingModeling the Ecosystem the Ecosystem

Response and Carbon CycleResponse and Carbon Cycle

to to Iron EnrichmentIron Enrichment in the in the

Equatorial PacificEquatorial Pacific

Fei CHAI

University of Maine

Lei Shi (University of Maine), M-S Jiang (UMass Boston), Yi Chao

(JPL/NASA), Francisco Chavez (MBARI), and Richard Barber (Duke)

Motivation of ModelingMotivation of Modeling

Test Response of Ecosystem Models

Investigate Long-term Consequences

Carbon Fluxes

Design Experiments

No Environmental Risks

Physical

Model

Nitrate

[NO3]

Advection

& Mixing

Small

Phytoplankton

[P1]NO3

Uptake

Micro-

Zooplankton

[Z1]

Grazing

Ammonium

[NH4]

Excretion

NH4

Uptake

Detritus-N

[DN]

Fecal

Pellet

SinkingSilicate

[Si(OH)4]

Diatoms

[P2]

Si-Uptake

N-UptakeMeso-

zooplankton

[Z2]

Sinking

Detritus-Si

[DSi]

GrazingFecal

Pellet

Sinking

Predation

Lost

Total CO2

[TCO2]

Biological

Uptake

Air-Sea

Exchange

Dissolution

Carbon, Silicate, Nitrogen Ecosystem ModelCoSiNE, Chai et al. 2002; Dugdale et al. 2002

Chai et al., 1996

Iron

Iron

Iron

3D Circulation-Ecosystem Modeling3D Circulation-Ecosystem Modeling

Modular Ocean Model (MOM)

Basin scale, coarse resolution (1o), 50 years simulation

Regional Ocean Model System (ROMS)Basin scale, finer resolution (1/2o), 50 years simulation

Basin scale, finer resolution (12.5-km), 16 years simulation

Central California Upwelling System (ROMS)

15-5-1.5 Km resolution, 1998 - 2003, and 2006

West Coast of the North America (NCOM)9 Km with physical data assimilation, 1998 - present

Gulf of Maine (POM)3 Km resolution, 2002 - present

IronEx II - In

IronEx II - Out

Quantum Yield (mol C mol photons-1)

IronFx II P vs. E

Fe

No Fe

SurfaceSurface NO NO33 Concentration - Annual MeanConcentration - Annual Mean

0.01

0.02

0.03

0.04

0.05

0.06

4/25 5/1 5/7 5/13 5/19 5/25

0

1

2

3

4

5

4/25 5/1 5/7 5/13 5/19 5/25

{day-1 (W/m2)-1}

P2max

{day-1}

P1max

{day-1}

Day 0 Day 7 Day 13 Day 19

TemporalChange of and P

max

Chai et al, GBC, in review

Chai et al, GBC, in review

Day 6

Day 0 Day 60Time

Chai et al

GBC, in review

Data from K. Busseler, WHOI

Iron

Added

No Iron

0.2751.3188.692.80.49

0.3122.572.226.50.37

e-

ratio

Export

Production(mmol Cm-2 day-1)

Primary

Production(mmol Cm-2 day-1)

New

Production(mmol Cm-2 day-1)

f-

ratio

Comparisons of Productions and Ratios

Detritus Si Anomaly in the Center of the Fe Patch

Chai et al

GBC, in review

ConclusionsConclusions

Need More Research on Iron Fertilization

Marine Ecosystem Response to Anthropogenic Perturbation

Modeled Ecosystem Response to Iron Addition

Nutrients, Chl a, PP, and TCO2

Interaction Between Phytoplankton and Zooplankton

Diatoms Increase First, Small Phytoplankton Lasts Longer

Increase of Vertical Carbon Fluxes

The System Needs about 90 days to Recover