CLIVAR WGOMD, Exeter April 2009 Magdalena Alonso Balmaseda 1 Contents: Sensitivity studies: fluxes versus ocean model ERA-Interim fluxes CORE-II simulations

CLIVAR WGOMD, Exeter April 2009 Magdalena Alonso Balmaseda 1

Contents:

• Sensitivity studies: fluxes versus ocean model

• ERA-Interim fluxes

• CORE-II simulations and initialization of decadal forecasts

• Input from the Pacific Panel regarding CORE-II ocean model integrations.


Uncertainties: Model versus forcing

• 2 models: HOPE and NEMO Similar horizontal resolution (~1 deg + eq refinement) Different grids, different vertical discretization, different numerics,

different physics

• 2 sets of forcing fluxes: ERA-40/OPS and ERA-Interim

• Integrations: 1989-2006 Daily fluxes Strong relaxation to SST


Heat flux corrections:

•In The Eastern Pacific the

solution depends mainly on the

ocean model

EQ1 162

1990 1995 2000 2005Time

-60

-40

-20

0

20

40

HOPE ERA40HOPE ERA-INTNEMO ERA40NEMO ERA-INT

IND2 162

1990 1995 2000 2005Time

-20

-10

0

10

20

30


EQIND 162

1990 1995 2000 2005Time

-30

-20

-10

0

10

20

30


•In the Equatorial Indian the

solution depends mainly on

the forcing fluxes


Total sea level

EastPacWestPac EqAtlEqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Total Sea Level

0 200 400 600 800EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Seasonal Sea Level

0 20 40 60 80 100EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Interannual Sea Level

0 10 20 30 40 50 60EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Differences due to models Differences due to forcing fluxes


Surface Salinity


NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Total Surface Salinity

-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Seasonal Surface Salinity

0 50 100 150EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Interannual Surface Salinity

0 20 40 60 80 100EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Differences due to models Differences due to forcing fluxes


Solar Heat flux: Era Interim – Era 40

Solar Heat Flux: ERA-INTERIM minus ERA-40 fluxesSolar Heat Flux: ERA-INTERIM minus ERA-40 fluxes

(W/m2): Min= -42.75, Max= 82.64, Int= 10.00

100E 160W 60WLongitude

60S

40S

20S

0

20N

40N

60NLa

titud

e

-65.00 -43.33 -21.67 0.00 21.67 43.33 65.00

ei_e4_vector_tau) Apr 25 2009


Flux correction term (~ SST error)


NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Total Flux Correction

-10 0 10 20EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Seasonal Flux Correction

0 2 4 6 8 10EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

Interannual Flux Correction

0 5 10 15 20EastPac

WestPac

EqAtl

EqInd

NsTrPac

SsTrPac

NsTrAtl

SsTrAtl

ERA-40 ERA-INTERIM


Wind Stress


Meridional wind stress time series EastPac

1990 1995 2000 2005Time

0.010

0.015

0.020

0.025

0.030

0.035

0.040 EQIND

1990 1995 2000 2005Time

0.000

0.005

0.010

0.015

0.020 NSTRATL

1990 1995 2000 2005Time

-0.030

-0.025

-0.020

-0.015

-0.010

WestPac

1990 1995 2000 2005Time

-0.020

-0.015

-0.010

-0.005

0.000

0.005 NSTRPAC

1990 1995 2000 2005Time

-0.026

-0.024

-0.022

-0.020

-0.018

-0.016 SSTRATL

1990 1995 2000 2005Time

0.022

0.024

0.026

0.028

0.030

0.032

0.034

0.036

EQATL

1990 1995 2000 2005Time

0.014

0.016

0.018

0.020

0.022

0.024

0.026

0.028 SSTRPAC

1990 1995 2000 2005Time

0.015

0.020

0.025

0.030

0.035 GLOBAL

1990 1995 2000 2005Time

-0.002

-0.001

0.000

0.001

0.002

0.003

ERA-40/OPS ERA-INTERIM


T300

SSH: ERA-INTERIM fluxes

0.3

0.3

0.7

SSH: ERA-INTERIM fluxes

(m): Min= -1.96, Max= 1.05, Int= 0.10


60S

40S

20S

0

20N

40N

60N

Latit

ude

-1.50-1.30-1.10-0.90-0.70-0.50-0.30-0.100.100.300.500.700.901.101.301.50

SSH: ERA-INTERIM minus ERA-40 fluxesSSH: ERA-INTERIM minus ERA-40 fluxes

(m): Min= -0.04, Max= 0.05, Int= 0.01


60S

40S

20S

0

20N

40N

60N

Latit

ude

-0.05 -0.03 -0.01 0.01 0.03 0.05ei_e4_vector_tau) Apr 27 2009


Correlation with Altimeter date

correl

0.0

0.2

0.4

0.6

0.8

EQ1 EQ3 EQATL EQIND NSTRPAC SSTRPAC NSTRATL SSTRATL

ERA-40 ERA-INTERIM


IFS/HOPE: impact of ocean observations

Global mean near-surface air temperature anomaly (2-year running mean applied) from the ECMWF re-forecasts. ERA40/OPS is used as a reference. The mean systematic error has been removed over the period 1960-2005.

IFS/HOPE (3 members) IFS/HOPE NoObs


Estimation of the Atlantic MOC

Assimilation No-Data Bryden etal 2005 Cunningham etal 2007

From Balmaseda etal 2007


Zonally integrated across the Atlantic meridional water velocity (103 m2/s) from the ECMWF ocean re-analysis (left) and the mean of the ten ECMWF

re-forecasts Assim (centre) and NoObs (right).

27°N

36°N

Profiles below 150m



Perceived Paradigm for initialization of coupled forecasts

Real world Model attractor

Medium rangeBeing close to the real world is perceived as advantageous. Model retains information for these time scales.

Model attractor and real world are close?

Decadal or longerNeed to initialize the model attractor on the relevant time and spatial scales.

Model attractor different from real world.

•Experiments:

•Uncoupled SST + Wind Stress + Ocean Observations (ALL)

•Uncoupled SST + Wind Stress (NO-OCOBS)

•Coupled SST (SST-ONLY) (Keenlyside et al 2008, Luo et al 2005)

Seasonal?Somewhere in the middle?

At first sight, this paradigm would not allow a seamless prediction system.


Impact of “real world” information on skill:

NINO3.4 RMS ERROR

ALL NO-OCOBS SST-ONLY

Adding information about the real world improves ENSO forecasts

From Balmaseda and Anderson 2009


NINO-W

EQATL

EQ3

STIO

WTIO

Reduction (%) in SST forecast error Range 1-3 months In Central/Western

Pacific, up to 50% of forecast skill is due to atmos+ocean observations.

Sinergy: > Additive contribution

Ocean~20%

Atmos ~25%

OC+ATM~55%



•Relation between drift and Amplitude of Interannual variability.

•Upwelling area penetrating too far west leads to stronger IV than desired.

Western Pacific


•Possible non linearity: is the warm drift interacting with the amplitude of ENSO?

Impact of Initialization

•Drift and Variability depend on Initialization !!

•More information corrects for model error, and the information is retained during the fc.

•Need “more balanced” initialization methods to prevent initialization shock hitting non linearities

Eastern Pacific ALL

NO-OCOBS

SST-ONLY

DRIFT

VARIABILITY


Pacific Panel Input:

• General proposal

0. Scientific Questions

1. Process oriented metrics (with/without observations)

2. Generic (blanket) metrics (with/without observations)

• METRICS and/or DIAGNOSTICS?

• Ongoing work on ENSO metrics to evaluate climate models (Pacific Panel, Eric Guilyardi).


CORE-II draft proposal from Pacific Panel (summary I)

• Relevant scientific questions Which processes control the SST off the South American coast, and why

models are not able to represent it correctly? Link to VOCALS Which are the determining factors for ocean models to represent the

depth and slope in equatorial thermocline? What controls the intensity and extension of the cold tongue? What is the heat budget of the warm pool? What determines the Equatorial heat content? What are the ocean heat

and fresh water transports at the equator? Which is the origin of the water masses in the Indonesian Troughflow

(ITF), which will determine the ITF heat and fresh water transports.? Which is the heat transport done by Tropical Instability Waves? SPICE science questions? Equatorial currents. Tsuchiya jets. Barrier Layer.


• 1 Relevant metrics for process studies 1.1 Observed Depth of the 20D isotherm along the Equator: Mean, SVD,

RMS/RMSE, and ACC (TAO/TRITON observations). Structure of the Tropical Instability Waves (TWI): Power spectra as

a function of latitude (Altimeter data and SST) Indonesian Throughflow (IT): Volume transport, Water mass

properties of the waters in that region. (Verifying observations?) Barrier Layer (Maes et al,…) South American Upwelling: VOCALS area SST, upwelling,

meridional velocity…Verifying observations: Stratus BUOY, Stratus cruise.

SPICE Region: U,V,T,S. There will be verifying observations

CORE-II draft proposal from Pacific Panel (summary II)


• 1 Relevant metrics for process studies 1.2 Non Observed Heat and volume transports by TWIs Heat budget in the warm pool region Indonesian Throughflow: heat and fresh water mass transport. Origin of waters in the IT? Trends in the Equatorial Circulation? …..



• 2. Generic metrics 2.1 Observed Temperature and Salinity profiles in prescribed areas (to include

attachment with Pacific_areas), compared with observations. Mean, SDV, mean difference/error and RMS/RMSE.

o T/S Observations are from WOA05 or from the Hadley Centre EN3. o T/S and Currents profiles at TAO/TRITON mooring location. Mean, SDV,

mean difference/error, RMS/RMSE and ACCTAO/TRITON observations. 2.2 Non observed: (comparable with reanalysis and obs-only

analysis) Zonal sections along the Equator of T,S,U,V,W: Mean, SDV, mean

difference, RMS. Meridional sections or T,S,U,V,W: Mean, SDV, mean difference,

RMS. Longitudes: 137E, 165E, 180,140W, 110W, 95W Others...

CORE-II draft proposal from Pacific Panel (summary III)



Global mean near-surface air temperature anomaly (2-year running mean applied) from the ECMWF re-forecasts. ERA40/OPS is used as a reference. The mean systematic error has been removed over the period 1960-2005.

IFS/HOPE (3 members) IFS/HOPE NoObs


Estimation of the Atlantic MOC

Assimilation No-Data Bryden etal 2005 Cunningham etal 2007

From Balmaseda etal 2007


Zonally integrated across the Atlantic meridional water velocity (103 m2/s) from the ECMWF ocean re-analysis (left) and the mean of the ten ECMWF

re-forecasts Assim (centre) and NoObs (right).

27°N

36°N

Profiles below 150m



Perceived Paradigm for initialization of coupled forecasts

Real world Model attractor

Medium rangeBeing close to the real world is perceived as advantageous. Model retains information for these time scales.

Model attractor and real world are close?

Decadal or longerNeed to initialize the model attractor on the relevant time and spatial scales.

Model attractor different from real world.

•Experiments:

•Uncoupled SST + Wind Stress + Ocean Observations (ALL)

•Uncoupled SST + Wind Stress (NO-OCOBS)

•Coupled SST (SST-ONLY) (Keenlyside et al 2008, Luo et al 2005)

Seasonal?Somewhere in the middle?

At first sight, this paradigm would not allow a seamless prediction system.



NINO3.4 RMS ERROR

ALL NO-OCOBS SST-ONLY

Adding information about the real world improves ENSO forecasts

From Balmaseda and Anderson 2009


NINO-W

EQATL

EQ3

STIO

WTIO

Reduction (%) in SST forecast error Range 1-3 months In Central/Western

Pacific, up to 50% of forecast skill is due to atmos+ocean observations.

Sinergy: > Additive contribution

Ocean~20%

Atmos ~25%

OC+ATM~55%




•Upwelling area penetrating too far west leads to stronger IV than desired.

Western Pacific


•Possible non linearity: is the warm drift interacting with the amplitude of ENSO?

Impact of Initialization

•Drift and Variability depend on Initialization !!

•More information corrects for model error, and the information is retained during the fc.

•Need “more balanced” initialization methods to prevent initialization shock hitting non linearities

Eastern Pacific ALL

NO-OCOBS

SST-ONLY

DRIFT

VARIABILITY


Pacific Panel Input:

• General proposal

0. Scientific Questions

1. Process oriented metrics (with/without observations)

2. Generic (blanket) metrics (with/without observations)

• METRICS and/or DIAGNOSTICS?

• Ongoing work on ENSO metrics to evaluate climate models (Pacific Panel, Eric Guilyardi).


CORE-II draft proposal from Pacific Panel (summary I)

• Relevant scientific questions Which processes control the SST off the South American coast, and why

models are not able to represent it correctly? Link to VOCALS Which are the determining factors for ocean models to represent the

depth and slope in equatorial thermocline? What controls the intensity and extension of the cold tongue? What is the heat budget of the warm pool? What determines the Equatorial heat content? What are the ocean heat

and fresh water transports at the equator? Which is the origin of the water masses in the Indonesian Troughflow

(ITF), which will determine the ITF heat and fresh water transports.? Which is the heat transport done by Tropical Instability Waves? SPICE science questions? Equatorial currents. Tsuchiya jets. Barrier Layer.


• 1 Relevant metrics for process studies 1.1 Observed Depth of the 20D isotherm along the Equator: Mean, SVD,

RMS/RMSE, and ACC (TAO/TRITON observations). Structure of the Tropical Instability Waves (TWI): Power spectra as

a function of latitude (Altimeter data and SST) Indonesian Throughflow (IT): Volume transport, Water mass

properties of the waters in that region. (Verifying observations?) Barrier Layer (Maes et al,…) South American Upwelling: VOCALS area SST, upwelling,

meridional velocity…Verifying observations: Stratus BUOY, Stratus cruise.

SPICE Region: U,V,T,S. There will be verifying observations



• 1 Relevant metrics for process studies 1.2 Non Observed Heat and volume transports by TWIs Heat budget in the warm pool region Indonesian Throughflow: heat and fresh water mass transport. Origin of waters in the IT? Trends in the Equatorial Circulation? …..



• 2. Generic metrics 2.1 Observed Temperature and Salinity profiles in prescribed areas (to include

attachment with Pacific_areas), compared with observations. Mean, SDV, mean difference/error and RMS/RMSE.

o T/S Observations are from WOA05 or from the Hadley Centre EN3. o T/S and Currents profiles at TAO/TRITON mooring location. Mean, SDV,

mean difference/error, RMS/RMSE and ACCTAO/TRITON observations. 2.2 Non observed: (comparable with reanalysis and obs-only

analysis) Zonal sections along the Equator of T,S,U,V,W: Mean, SDV, mean

difference, RMS. Meridional sections or T,S,U,V,W: Mean, SDV, mean difference,

RMS. Longitudes: 137E, 165E, 180,140W, 110W, 95W Others...

CORE-II draft proposal from Pacific Panel (summary III)

Documents

CLIVAR WGOMD, Exeter April 2009 Magdalena Alonso Balmaseda 1 Contents: Sensitivity studies: fluxes versus ocean model ERA-Interim fluxes CORE-II simulations