eastern pacific surface fluxes observed and simulated by coupled gcms

Eastern Pacific surface fluxes observedand simulated by coupled GCMs

Simon de Szoeke & Chris Fairall

de Szoeke et al. 2010: Surface Flux Observations on the Southeastern Tropical Pacific Ocean and Attribution of SST Errors in Coupled Ocean–Atmosphere Models, J. Climate.

surface heat budget

0 = –∂/∂t SSTturbulent evaporation and sensible fluxnet radiationocean residual

annual average heat budget

+ +

= 0

“observed” coupled GCM simulations

Ocean residual flux

Colbo and Weller 2007

surface ocean heat budgetOctober

ship-observedheat fluxes20°S, October

surface heat budgetΔS > 40 W m-2

obs.

surface heat budget errors

obs.

solar longwave

surface downwelling radiationW

m-2

longitude

clear

full

S0: Iqbal 1988 R0: Hare 2005

solarlongwave

surface downwelling radiationW

m-2

longitude

solar transmission

clear

cloudyfull

longwave cloud effect

10 minuteaverages

Cloud forcing phase diagrampolarcold dry columnlow sun

tropicalwarm moistcolumn,high sun

Cloud forcing phase diagram

2(R–R

0) >

|S–S

0| +

10

W m

-2

Daily average cloud radiative forcing

xx: solar-weighted cloud fractionred: 2(R–R0) > |S–S0| + 10 W m-2

longwave

solar

models

ship

buoy

ISCCP

model surface cloud forcing

Does insolation explain SST?

no

surface heat budget0 =

–∂/∂t SSTturbulent evaporation and sensible fluxnet radiationocean residual =

Ekman transportgeostrophic transportupwellingeddy flux divergence

damp SST

the end

?