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
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
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
100E 160W 60WLongitude
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
100E 160W 60WLongitude
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
ORAS4 Ocean Reanalysis M.A. Balmaseda
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
100E 160W 60WLongitude
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
100E 160W 60WLongitude
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
100E 160W 60WLongitude
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
100E 160W 60WLongitude
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 1 2 3 4 5 6 7Forecast time (months)
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 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
ATL3 034a anomaly correlation
0 1 2 3 4 5 6 7Forecast time (months)
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
ATL3 034a rms errors
Fcast feik Fcast ff5e Persistence Ensemble sd
MAGICS 6.12 windmill - neh Fri Sep 3 10:59:05 2010
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
EQIND 034a anomaly correlation
0 1 2 3 4 5 6 7Forecast time (months)
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
EQIND 034a rms errors
Fcast feik Fcast ff5e Persistence Ensemble sd
MAGICS 6.12 windmill - neh Fri Sep 3 10:59:05 2010
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
nwrt NCEP adjusted OIv2 1971-2000 climatology
NSTRATL 034a anomaly correlation
0 1 2 3 4 5 6 7Forecast time (months)
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
NSTRATL 034a rms errors
Fcast feik Fcast ff5e Persistence Ensemble sd
MAGICS 6.12 windmill - neh Fri Sep 3 10:59:05 2010
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
NSTRPAC 034a anomaly correlation
0 1 2 3 4 5 6 7Forecast time (months)
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
NSTRPAC 034a rms errors
Fcast feik Fcast ff5e Persistence Ensemble sd
MAGICS 6.12 windmill - neh Fri Sep 3 10:59:05 2010
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
SSTRATL 034a anomaly correlation
0 1 2 3 4 5 6 7Forecast time (months)
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
SSTRATL 034a rms errors
Fcast feik Fcast ff5e Persistence Ensemble sd
MAGICS 6.12 windmill - neh Fri Sep 3 10:59:05 2010
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
% rms EQUA Potential Temperature
0 10 20 30 40 50 60%
-800
-600
-400
-200
0
Depth
(m
)
CONTROL+BCCONTROL
ORAS4-NoBCORAS4
Global MidLat: North MidLat: South
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
Global MidLat: North MidLat: South
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
Global MidLat: North MidLat: South
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
% rms EQUA Potential Temperature
0 2 4 6 8%
-500
-400
-300
-200
-100
0
Dep
th (m
)
NoMoorNoArgo
NoAltiORAS4-NoBC
ORAS4
% rms EQUA Potential Temperature
0 2 4 6 8%
-500
-400
-300
-200
-100
0
Dep
th (m
)
NoMoorNoArgo
NoAltiORAS4-NoBC
ORAS4
Relative RMS (%) FirstGuess – Obs. Temperature
Global MidLat: North MidLat: South
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
Global MidLat: North MidLat: South
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
NoArgoNoMoorNoAltiORAS4
GLOBAL 364
1994 1996 1998 2000 2002 2004 2006 2008 2010Time
5.40
5.41
5.42
5.43
5.44
5.45
NoArgoNoMoorNoAltiORAS4
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
fa9p_oref_19932008_1_sossheig_stats.ps) Aug 26 2010
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
fa9p_oref_19932008_1_sossheig_stats.ps) Aug 27 2010
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
80W 60W 40W 20WLongitude
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
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
feha.nc sobarstffeha.nc sobarstf
(Sv): Min= -6.72, Max= 6.37, Int= 1.00
80W 60W 40W 20WLongitude
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
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
fa9p_oref_19932008_1_sossheig_stats.ps) Aug 26 2010
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
MOC ATL26N level= 1267.54
1960 1970 1980 1990 2000 2010Time
10
12
14
16
18
ORAS4CONTROLCONTROL+BC
MOC ATL26N level= 1267.54
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
ORAS4 Ocean Reanalysis M.A. Balmaseda
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