Slide 1 The ECMWF new operational Ocean Re-Analyses System 4 (ORAS4) Magdalena A. Balmaseda, Kristian Mogensen, Anthony Weaver, and NEMOVAR consortium

Slide 1

The ECMWF new operational

Ocean Re-Analyses System 4

(ORAS4)

Magdalena A. Balmaseda , Kristian Mogensen, Anthony

Weaver, and NEMOVAR consortium

Outline

• The ORA-S4 ocean reanalyses 1st operational implementation of NEMOVAR ORAS4 description General performance

• OSEs and other sensitivity experiments

• Assessing Robustness of climate signals Heat Uptake

• Atlantic MOC

• Summary

NEMOVAR: Variational Data Assimilation system for the NEMO Ocean Model

•Collaboration among several institutions: •CERFACS, Met Office, ECMWF, INRIA, Un of Reading

•Incremental formulation: outer/inner loops

•Covariances as in Weaver et al (OPAVAR), except for altimeter•Geostrophy, T/S relationship•Altimeter projection based on stratification

•Automatic QC (consistent with EN3 data set)

•Observation operator in NEMO

•Bias correction algorithm

•NEMOVAR in ORAS4: •Incremental 3Dvar FGAT. 10 day assim cycle. IAU

ECWMF: ORAS4 Ocean Re-Analysis• It replaces the previous ORAS3 (based on HOPE/OI)

• It uses NEMO/NEMOVAR, ORCA1 configuration, 42 levels (ORCA1_Z42_v2)

• NEMO V3.0 + Local Modifications.• Forced by ERA40 (until 1989) + ERA Interim (after 1989)

• Assimilates Temperature/Salinity from EN3 (corrected XBT’s). Alongtrack altimeter

• Strong relaxation to SST (OI_v2) until 2010. OSTIA SST thereafter

• Offline+Online model bias correction scheme (T/S and pressure gradient): Offline bias term estimated from Argo Period Latitudinal dependence of the P/T/S bias: P strong at the Eq, weak at mid latitudes. Viceversa with T/S

• 5 ensemble members (perturbations to wind, initial deep ocean, observation coverage)

ORAS4 Ocean Reanalysis M.A. Balmaseda

Estimating Bias Correction From Argo Period

Temperature Bias Estimation from Argo: 300m-700mTemperature Bias Estimation from Argo: 300m-700m

(C/h): Min= -1.2e-03, Max= 7.5e-04, Int= 4.0e-05

100E 160W 60WLongitude

50S

0

50N

Latit

ude

-2.0e-04 -1.2e-04 -4.0e-05 4.0e-05 1.2e-04 2.0e-04

Temperature Bias Estimation from WOA05: 300m-700mTemperature Bias Estimation from WOA05: 300m-700m

(C/h): Min= -1.5e-04, Max= 2.0e-04, Int= 4.0e-05


50S

0

50N

Latit

ude

-2.0e-04 -1.2e-04 -4.0e-05 4.0e-05 1.2e-04 2.0e-04

fa9p_oref_19932008_1_sossheig_stats.ps) Jun 16 2010

Salinity Bias Estimation from Argo:300m-700mSalinity Bias Estimation from Argo:300m-700m

(psu/h): Min= -1.0e-04, Max= 1.2e-04, Int= 5.0e-06


50S

0

50N

Latit

ude

-5.0e-05 -4.0e-05 -3.0e-05 -2.0e-05 -1.0e-05 -1.8e-12 1.0e-05 2.0e-05 3.0e-05 4.0e-05 5.0e-05

Salinity Bias Estimation from WOA05: 300m-700mSalinity Bias Estimation from WOA05: 300m-700m

(psu/h): Min= -2.3e-05, Max= 2.4e-05, Int= 5.0e-06


50S

0

50N

Latit

ude

-5.0e-05 -4.0e-05 -3.0e-05 -2.0e-05 -1.0e-05 -1.8e-12 1.0e-05 2.0e-05 3.0e-05 4.0e-05 5.0e-05

fa9p_oref_19932008_1_sossheig_stats.ps) Jun 16 2010

The offline bias correction is estimated from Argo. The correction is applied during the data assimilation process in the production of long climate reanalysis (from 19570901 to present)

Large spread in the deep ocean (poorly observed)

TEMP

SAL

800m 2000m

Which SST product to use?

OIV2_025_AVHRR: bias cold in the global mean (regional differences)

Bias decreases with time. Weaker interannual variability

Fit to insitu Temperature: bias cold in tropics, better in mid latitudes.

DECISION: OIV2_1x1 until 2010 and OSTIA thereafter


Assimilating Altimeter Data

•Assimilation of sea level anomalies: along track (new)•SuperObbing: rms of superobs used to account for representativeness error•Remove global sea level prior to assimilation•Multivariate relationship: How to project sea level into the subsurface T and S (next)

•Assimilation of Global Sea Level Trends (from gridded maps)•Global sea level is assimilated: FWF=SL_trendobs-SH_trendmodel

•Prior to Alti era the closure is with clim SL. Smoothed daily values for real time

•Choice of MDT (Mean Dynamic Topography)•External Product: Rio9,

•Tried, but not good results, due to the mismatch between model and Rio9 •It needs more work to have an “observation” bias correction•For S4: MDT from an assimilation run using T and S

•Balance relationship between sea level and T/S is a linear formulation of the Cooper and Haines scheme, taking into account the stratification of the water column

Multivariate balance for AltimeterIN NEMOVAR the balance is between sea level and a definition of steric height (vertical integration of density):

(1) )( :form lincrementain or ,00

zrefzref

dzzdz

Original formulation of NEMOVAR

αref and βref are calculated by linearizing the equation of estate using the background T/S values as reference. Comments:

i) zref=1500m is arbitrary. An attempt to take into account that baroclinicity is low below this level. Can we account for the vertical stratification more universally?

ii) this can lead to increments in model levels with large dz

SandT

STmz

refref

refref

refref

ref

(2) 1500

Modifications

A):Weighting based on stratification. Use BV frequency to calculate αN and βN instead of equation of state

B) Do not double-count balance-salinity corrections

2 2 2 2;

z zN N z N T N S

z T S

2

2

ref ref ref ref

ref ref

T S S TN

z z T z

z S T zN T T

T T z T

Assessment of the ORA-S4 re-analysisChoose a baseline: the CONTROL (e.i., no data assim)

1. Assim Intrinsic Metrics• Fit to obs (first-guess minus obs): Bias, RMS

• Error growth (An-obs versus FG-obs)

• Consistency: Prescribed/Diagnosed B and R

This is insufficient to assess a Reanalysis product

2. Spatial/temporal consistency: long time series and spatial maps• Time correlation with Mooring currents

• Correlation with altimeter/Oscar currents

• Transports (MOC and RAPID): short time series

Quite limited records. Not always independent data

3. Skill of Seasonal Forecasts

Expensive. Model error can be a problem.

4. Process studies: Example impact of assimilation on the MOC

rms EQ2 Potential Temperature

0.0 0.5 1.0 1.5 2.0 2.5rms EQ2 Potential Temperature

-500

-400

-300

-200

-100

0

Depth

(m

)

rms EQIND Potential Temperature

0.0 0.5 1.0 1.5 2.0rms EQIND Potential Temperature

-500

-400

-300

-200

-100

0

Depth

(m

)

rms TRPAC Potential Temperature

0.4 0.6 0.8 1.0 1.2 1.4rms TRPAC Potential Temperature

-500

-400

-300

-200

-100

0

Depth

(m

)

rms GLOBAL Potential Temperature

0.6 0.8 1.0 1.2 1.4 1.6rms GLOBAL Potential Temperature

-500

-400

-300

-200

-100

0

Depth

(m

)

CONTROL ASSIM: T+S ASSIM: T+S+Alti

EQ Central Pacific EQ Indian Ocean

TROPICAL Pacific GLOBAL

Altimeter Improves the fit to InSitu Temperature Data

RMSE of 10 days forecast

NEMOVAR re-an: verif. against altimeter data

correl (1): fe5x sossheig ( 1993-2008 ) correl (1): fe5x sossheig ( 1993-2008 )

(ndim): Min= -0.37, Max= 1.00, Int= 0.02


60S

40S

20S

0

20N

40N

60N

Latitud

e

0.40 0.44 0.48 0.52 0.56 0.60 0.64 0.68 0.72 0.76 0.80 0.84 0.88 0.92 0.96 1.00

RMSE (1): fe5x sossheig (1993-2008) RMSE (1): fe5x sossheig (1993-2008)

(m): Min= 0.01, Max= 0.15, Int= 0.01


60S

40S

20S

0

20N

40N

60N

Latitud

e

0.02 0.04 0.06 0.08 0.10

rms/signal(1): fe5x sossheig (1993-2008) rms/signal(1): fe5x sossheig (1993-2008)

(N/A): Min= 0.10, Max= 3.18, Int= 0.20


60S

40S

20S

0

20N

40N

60N

Latitud

e

0.00 0.40 0.80 1.20 1.60 2.00

sdv_fe5x/sdv_aviso (1): sossheig (1993-2008) sdv_fe5x/sdv_aviso (1): sossheig (1993-2008)

(N/A): Min= 0.22, Max= 2.74, Int= 0.20


60S

40S

20S

0

20N

40N

60N

Latitud

e

0.00 0.40 0.80 1.20 1.60 2.00

fa9p_oref_19932008_1_sossheig_stats.ps) Aug 4 2010

NEMOVAR T+S

NEMOVAR-S4 T+S+Alti

NEMO NoObs

Impact of NEMOVAR in SST forecasts Prototype of S4: latest NEMOVAR+36r4. Anomaly Correlation

0 1 2 3 4 5 6 7Forecast time (months)

0.4

0.5

0.6

0.7

0.8

0.9

1

Anom

aly

corre

latio

n

wrt NCEP adjusted OIv2 1971-2000 climatology

EQ2 034a anomaly correlation


0

0.2

0.4

0.6

0.8

1

Rm

s er

ror

Ensemble sizes are 5 (feik) and 5 (ff5e) 64 start dates from 19930201 to 20081101

EQ2 034a rms errors

Fcast feik Fcast ff5e Persistence Ensemble sd

MAGICS 6.12 windmill - neh Fri Sep 3 10:59:05 2010


0.4

0.5

0.6

0.7

0.8

0.9

1

Anom

aly

corre

latio

n


ATL3 034a anomaly correlation


0

0.2

0.4

0.6

0.8

1

Rm

s er

ror


ATL3 034a rms errors




0.4

0.5

0.6

0.7

0.8

0.9

1

Anom

aly

corre

latio

n


EQIND 034a anomaly correlation


0

0.2

0.4

0.6

0.8

1

Rm

s er

ror


EQIND 034a rms errors




0.4

0.5

0.6

0.7

0.8

0.9

1

Anom

aly

corre

latio

nwrt NCEP adjusted OIv2 1971-2000 climatology

NSTRATL 034a anomaly correlation


0

0.2

0.4

0.6

0.8

1

Rm

s er

ror


NSTRATL 034a rms errors




0.4

0.5

0.6

0.7

0.8

0.9

1

Anom

aly

corre

latio

n


NSTRPAC 034a anomaly correlation


0

0.2

0.4

0.6

0.8

1

Rm

s er

ror


NSTRPAC 034a rms errors




0.4

0.5

0.6

0.7

0.8

0.9

1

Anom

aly

corre

latio

n


SSTRATL 034a anomaly correlation


0

0.2

0.4

0.6

0.8

1

Rm

s er

ror


SSTRATL 034a rms errors



NEMOVAR NEMO-NoObs

NEMOVAR consistently improves the forecast skill of SST at different lead times and different regions

CENTRAL EQ. PACIFIC CENTRAL EQ. ATLANTIC EQ. INDIAN

N SubTrop PACIFIC N SubTrop ATLANTIC S SubTrop ATLANTIC

Experiments Conducted

• ORAS4: 1958-onwards

• ORAS4 NoBC: as ORAS4 no Bias Correction. 1958-2010

• CONTROL: No assimilation. 1958-2010

• CONTROL BC: Control with offline Bias Correction. 1958-2010

• CONTROL INI: Starting from CONTROL 2008. 1958-2010

• NoAlti: ORAS4 removing Altimeter

• NoMoor: ORAS4 removing Mooring

• NoArgo: ORAS4 removing Argo

TRIND Depth of the 20 degrees isotherm

1960 1980 2000Time

-130

-125

-120

-115

CONTROL INICONTROL+BCORAS4-NoBCCONTROLORAS4

RMS FirstGuess – Obs. Temperaturerms GLOBAL Potential Temperature

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms NXTRP Potential Temperature

0.5 1.0 1.5 2.0-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms SXTRP Potential Temperature

0.4 0.6 0.8 1.0 1.2 1.4-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms TROP Potential Temperature

0.0 0.5 1.0 1.5 2.0-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms EQUA Potential Temperature

0.0 0.5 1.0 1.5 2.0-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms EQUA Potential Temperature

0.0 0.5 1.0 1.5 2.0-800

-600

-400

-200

0

Dep

th (m

)CONTROL+BC

CONTROLORAS4-NoBC

ORAS4

Global MidLat: North MidLat: South

Tropics Equator

Relative RMS (%) FirstGuess – Obs. Temperature% rms GLOBAL Potential Temperature

0 10 20 30 40 50%

-800

-600

-400

-200

0

Depth

(m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms NXTRP Potential Temperature

0 10 20 30 40 50%

-800

-600

-400

-200

0

Depth

(m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms SXTRP Potential Temperature

0 10 20 30%

-800

-600

-400

-200

0

Depth

(m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms TROP Potential Temperature

0 10 20 30 40 50%

-800

-600

-400

-200

0

Depth

(m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms EQUA Potential Temperature

0 10 20 30 40 50 60%

-800

-600

-400

-200

0

Depth

(m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4


0 10 20 30 40 50 60%

-800

-600

-400

-200

0

Depth

(m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4


Tropics Equator

rms GLOBAL Salinity

0.0 0.1 0.2 0.3 0.4 0.5-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms NXTRP Salinity

0.0 0.1 0.2 0.3 0.4 0.5 0.6-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms SXTRP Salinity

0.05 0.10 0.15 0.20 0.25-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms TROP Salinity

0.0 0.1 0.2 0.3 0.4-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms EQUA Salinity

0.0 0.1 0.2 0.3 0.4-800

-600

-400

-200

0D

epth

(m)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

rms EQUA Salinity

0.0 0.1 0.2 0.3 0.4-800

-600

-400

-200

0

Dep

th (m

)CONTROL+BC

CONTROLORAS4-NoBC

ORAS4


Tropics Equator

RMS FirstGuess – Obs. Salinity

% rms GLOBAL Salinity

0 20 40 60 80 100%

-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms NXTRP Salinity

0 20 40 60 80 100%

-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms SXTRP Salinity

0 20 40 60 80%

-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms TROP Salinity

0 10 20 30 40 50 60%

-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms EQUA Salinity

0 10 20 30 40 50%

-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4

% rms EQUA Salinity

0 10 20 30 40 50%

-800

-600

-400

-200

0

Dep

th (m

)

CONTROL+BCCONTROL

ORAS4-NoBCORAS4


Tropics Equator

Relative RMS (%) FirstGuess – Obs. Salinity

% rms GLOBAL Potential Temperature

0 5 10 15 20%

-500

-400

-300

-200

-100

0D

epth

(m)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

% rms NXTRP Potential Temperature

0 5 10 15 20%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

% rms SXTRP Potential Temperature

0 2 4 6 8 10%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

% rms TROP Potential Temperature

0 2 4 6 8 10 12%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4


0 2 4 6 8%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4


0 2 4 6 8%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

Relative RMS (%) FirstGuess – Obs. Temperature


Tropics Equator

% rms GLOBAL Salinity

0 10 20 30 40 50%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

% rms NXTRP Salinity

0 10 20 30 40 50%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

% rms SXTRP Salinity

0 5 10 15 20 25 30%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

% rms TROP Salinity

0 5 10 15 20 25%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

% rms EQUA Salinity

0 5 10 15 20%

-500

-400

-300

-200

-100

0D

epth

(m)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4

% rms EQUA Salinity

0 5 10 15 20%

-500

-400

-300

-200

-100

0

Dep

th (m

)

NoMoorNoArgo

NoAltiORAS4-NoBC

ORAS4


Tropics Equator

Relative RMS (%) FirstGuess – Obs. Salinity

OSES for Assessing Robustness of Climate Signals

• Ocean Heat Uptake

• MOC

• Sea Level

After 2000, the deep ocean warms faster than the upper ocean. How robust is this?

ORA-S4: GLOBAL OCEAN HEAT CONTENT (*10̂ 10 J/m2)

1960 1980 2000Time

-0.01

0.00

0.01

0.02

0.03

0.04

Upper 300mUpper 700mTotal Depth

GLOBAL Heat Content Upper 300m (1xe10 J/m2)

1960 1980 2000Time

1.96

1.98

2.00

2.02ORAS4CONTROLORAS4-NoBCCONTROL+BC

GLOBAL Heat Content Upper 300m (1xe10 J/m2)

1994 1996 1998 2000 2002 2004 2006 2008 2010Time

1.955

1.960

1.965

1.970

1.975

1.980

1.985

NoArgoNoMoorNoAltiORAS4

GLOBAL 264

1994 1996 1998 2000 2002 2004 2006 2008 2010Time

3.04

3.05

3.06

3.07

3.08


GLOBAL 364

1994 1996 1998 2000 2002 2004 2006 2008 2010Time

5.40

5.41

5.42

5.43

5.44

5.45


300m 700m

total

Without Argo the ocean heat trends are weaker….

anom fi8y GLOBAL

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010Time

-0.01

0.00

0.01

0.02

0.03

NoArgo 300mNoArgo 700mNoArgo Total

anom fi86 GLOBAL

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010Time

-0.01

0.00

0.01

0.02

0.03

NoMoor 300mNoMoor 700mNoMoor Total

But still the deep ocean warms faster…

300m

700m

total

300m

700m

total

ASSIMILATION AND AMOC

NEMOVAR

NEMO -NoObs NEMOVAR-NEMONoObs

Assimilation decreases MOC South of 40N.

In Increases MOC in the North Atlantic

fe5y zottmedxdz 700mfe5y zottmedxdz 700m

(Sverdrup): Min= -3.34, Max= 23.38, Int= 2.00

100W 80W 60W 40W 20WLongitude

10N

20N

30N

40N

50N

Latitu

de

-21.00 -16.80 -12.60 -8.40 -4.20 0.00 4.20 8.40 12.60 16.80 21.00


fe5x - fe5y zottmedxdz 700mfe5x - fe5y zottmedxdz 700m

(Sverdrup): Min= -1.84, Max= 2.93, Int= 0.30

100W 80W 60W 40W 20WLongitude

10N

20N

30N

40N

50N

Latitu

de

-3.10 -2.50 -1.90 -1.30 -0.70 -0.10 0.50 1.10 1.70 2.30 2.90


NEMO CONTROL NEMOASSIM-CONTROL

dxzxV

dzzxvzxV

ref

z

*),(

),(),(0

100OW 90OW 80OW 70OW 60OW 50OW 40OW 30OW 20OW 10OW 0O

Longitude

10ON

15ON

20ON

25ON

30ON

35ON

40ON

45ON

50ON

Latitude

Plot resolution is 1.4063 in x and 1 in yHorizontal section at 1450. metres depthMeridional transport contoured every 1 m2/sMOC: f56f - 0001

Interpolated in y20090101 ( 31 day mean)

difference from20090101 ( 31 day mean)

-12

-10

-8

-6

-4

-2

1

3

5

7

9

11

MAGICS 6.12 windmill - neh Wed Sep 1 19:35:16 2010

100OW 90OW 80OW 70OW 60OW 50OW 40OW 30OW 20OW 10OW 0O

Longitude

10ON

15ON

20ON

25ON

30ON

35ON

40ON

45ON

50ON

Latitude

Plot resolution is 1.4063 in x and 1 in yHorizontal section at 2100. metres depthMeridional transport contoured every 1 m2/sMOC: f56f - 0001

Interpolated in y20090101 ( 31 day mean)

difference from20090101 ( 31 day mean)

-12

-10

-8

-6

-4

-2

1

3

5

7

9

11

MAGICS 6.12 windmill - neh Wed Sep 1 19:35:16 2010

HOPE/OIAssim- Control: Integral(vdz) CI:1m2/s

• In NEMOVAR: North of 20N, Assim produces

stronger/narrower WBC At 26N, Assimilation reduces the FST

• In HOPE/OI Assim increases WBC at all latitudes. Effect of bathimetry?

Zref=700m

fe5x.nc sobarstffe5x.nc sobarstf

(Sv): Min= -44.40, Max= 58.54, Int= 5.00

80W 60W 40W 20WLongitude

10N

20N

30N

40N

50N

60N

Latitud

e-55.00-45.00-35.00-25.00-15.00 -5.00 5.00 15.00 25.00 35.00 45.00 55.00

fe5x.nc sobarstffe5x.nc sobarstf

(Sv): Min= -10.23, Max= 9.43, Int= 1.00


10N

20N

30N

40N

50N

60N

Latitud

e

-10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00fa9p_oref_19932008_1_sossheig_stats.ps) Aug 27 2010

feha.nc sobarstffeha.nc sobarstf

(Sv): Min= -44.58, Max= 53.36, Int= 5.00


10N

20N

30N

40N

50N

60N

Latitud

e

-55.00-45.00-35.00-25.00-15.00 -5.00 5.00 15.00 25.00 35.00 45.00 55.00

feha.nc sobarstffeha.nc sobarstf

(Sv): Min= -6.72, Max= 6.37, Int= 1.00


10N

20N

30N

40N

50N

60N

Latitud

e

-10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00fa9p_oref_19932008_1_sossheig_stats.ps) Aug 27 2010

fe5y.nc sobarstffe5y.nc sobarstf

(Sv): Min= -41.35, Max= 49.11, Int= 5.00


10N

20N

30N

40N

50N

60N

Latitud

e

-55.00 -45.00 -35.00 -25.00 -15.00 -5.00 5.00 15.00 25.00 35.00 45.00 55.00


A) CONTROL B) ASSIM C) ASSIM-NoCoast

ASSIM-CONTROL NoCoast- CONTROL

Barotropic Stream FunctionAssimilation (B) has stronger Subpolar and Subtropical Gyres

Assim tends to shift the subtropical gyre northward. Discontinuity off the Florida Coast

In S4: MOC at 26N

ASSIM1 CONTROL BC ASSIM-NoCoast ORA-S4 RAPID ATL26N

1960 1970 1980 1990 2000Time

10

12

14

16

18

20 fe5x 1004.96feha 1010.16ff2w 1002.91fe5y 1006.98RAPID 1000.00

MOC ATL26N level= 1267.54

1960 1970 1980 1990 2000 2010Time

10

12

14

16

18

ORAS4CONTROL

Footer-text Slide 32


1960 1970 1980 1990 2000 2010Time

10

12

14

16

18

ORAS4CONTROLCONTROL+BC


1960 1970 1980 1990 2000 2010Time

10

12

14

16

18

ORAS4CONTROLCONTROL+BCCONTROL INI2008

Atlantic MOC at 26 North 800m

Latitude/Time: 1000m

Southward Propagation?Equatorial Events. How deep?

Latitude/Time at 3000m

Footer-text Slide 34

Southward propagation is more clear. Post 2000 –ve unusually long

Comparison with RAPID DATA

MOC

2002 2004 2006 2008 20100

10

20

30Ekman

2002 2004 2006 2008 2010-10

-5

0

5

10

RAPIDNoArgoNoMoor

NoAltiORAS4

MOC-Ekman

2002 2004 2006 2008 20100

10

20

30


Summary•ORAS4 is the new operational ocean reanalysis at ECMWF

•1st operational implementation of NEMOVAR

•Generally good performance: NEMOVAR reduces subsurface biases, improves the interannual variability and forecast skill

•Still a challenge: how to assimilate data near the coast

•Evaluating Ocean Reanalysis is more than just fit to data. An evaluation of the temporal consistency of the signals is needed.

•OSEs are a good diagnostic tool for robustness of climate signals•They are also a diagnostic for data assimilation systems•The OSES conducted show positive impact of different observing systems, although, in the presence of bias correction schemes is not always easy to isolate the effects.

•NEXT:•Nice webpage•¼ of degree ocean reanalysis (next 2-3 years)•Exploitation of ensemble information•More coupling

Documents

Slide 1 The ECMWF new operational Ocean Re-Analyses System 4 (ORAS4) Magdalena A. Balmaseda, Kristian Mogensen, Anthony Weaver, and NEMOVAR consortium