joint proposal to wgomd for a community ocean model experiment
DESCRIPTION
Joint Proposal to WGOMD for a community ocean model experiment. Background. Seasonal Forecasts is an ideal test bed to asses the quality of the GCMS used in future climate projections: Need ocean initial conditions to carry out experiments - PowerPoint PPT PresentationTRANSCRIPT
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 1
Joint Proposal to WGOMD for a community ocean model experiment
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 2
Background
• Seasonal Forecasts is an ideal test bed to asses the quality of the GCMS used in future climate projections:
Need ocean initial conditions to carry out experiments Not all the groups have ocean data assimilation systems in place.
• WGOMD is about to discuss experimental setup to asses ocean model performance in the representation of the inter-annual variability. Possibility of X-Panel interaction and feedback.
• The proposed experiment could answer some outstanding questions about the key elements needed to improve the representation of the Pacific basin and ENSO.
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 3
Questions from the Pacific Panel
• There are known model deficiencies in the representation of the Pacific climate:
Upwelling off the South American Coast Cold tongue penetrating too far west Too weak/too strong east-west slope of the thermocline Equatorial heat content (IT/meridional transport, vertical mixing) …
• Is it possible to say which are the dominant source of error?
Forcing fields? Model parameterizations/configuration? Model resolution? Parameterization of air-sea interaction?
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 4
Proposal
• Conduct a long ocean model simulation (20-40 years) with a variety of models, using inter-annually varying atmospheric reanalysis (ERA40-ENACT, NCEP-CORE, JMR-25…). This long integration can be used as:
a CNTL experiment to answer some of the above questions (see later)
To provide initial conditions for concerted seasonal forecast experiments.
• Conduct additional integrations with each model (optional), to test sensitivities:
Different forcing fields Different resolution Different parameterization, bulk formulae, ….
• Need to agree the specifications for the CNTL integration.
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 5
Sensitivities: Compute and Compare
•Sensitivity to Forcing fluxes:
•Sensitivity to Resolution:
•Sensitivity to Model:
•Sensitivity to Bulk Formula:
•Sensitivity to P-parameterization:
CteBPMRFXF
,,,
CteBPMFRXR
,,,
CteBPRFMXM
,,,
CteRPMFBXB
,,,
CteBRMFPXP
,,,
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 6
Sources of Uncertainty
EQPAC
0.00
0.05
0.10
0.15
0.20
spre
ad
EQATL
0.00
0.05
0.10
0.15
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ad
EQIND
0.00
0.05
0.10
0.15
0.20
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NINO3
0.00
0.05
0.10
0.15
0.20
0.25
0.30
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ad
DTRATL
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
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ad
INDPL
0.0
0.1
0.2
0.3
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ad
All
ERA40
ERA40-No data
ERA40-Assim
12m-rm seasonal anom: EQPAC Averaged temperature over the top 300m
1950 1960 1970 1980 1990 2000Time
-1.0
-0.5
0.0
0.5
1.0
1.5
allsdv_ensm= 0.269spread= 0.239s/n_ensm = 1.127
era40sdv_ensm= 0.278spread= 0.145s/n_ensm = 1.912
era40-ctrlsdv_ensm= 0.338spread= 0.117s/n_ensm = 2.887
era40-assmsdv_ensm= 0.332spread= 0.085s/n_ensm = 3.910
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 8
Assimilation and Uncertainty T300
Long period 1956-2005:
Large part of uncertainty comes
from forcing fluxes
1956-2005
EQPAC
0.00
0.05
0.10
0.15
0.20
spre
ad
EQATL
0.00
0.05
0.10
0.15
spre
ad
EQIND
0.00
0.05
0.10
0.15
0.20
spre
ad
TRPAC
0.00
0.02
0.04
0.06
0.08
0.10
0.12
spre
ad
TRATL
0.00
0.02
0.04
0.06
0.08
0.10
0.12
spre
ad
NPAC
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
spre
ad
NATL
0.00
0.02
0.04
0.06
0.08
0.10
spre
ad
GLOBAL
0.00
0.01
0.02
0.03
0.04
0.05
0.06
spre
ad
EQPAC EQATL EQIND TRPAC
TRATL NPAC NATL GLOBAL
ALL
SAME FORCING (ERA40)
OCEAN MODEL
ASSIMILATION SCHEME
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 10
-1.5 -1.2 -0.9 -0.6 -0.3 0temperature
-400
-200
Dep
th (m
)
S3-a S3-cMean(199301-200201) of Model minus Observations
eq3-All in situ data
50OE 100OE 150OE 160OW 110OW 60OW 10OW
Longitude
500
400
300
200
100
0
Depth
(m
etr
es)
500
400
300
200
100
0Plot resolution is 1.4063 in x and 10 in yZonal section at 0.00 deg NICODE=178 contoured every 0.0002 XXXHOPE gcm:: 0001
Interpolated in y 0 ( 31 day mean)
difference from20020101 ( 31 day mean)
-0.0008
-0.0006-0.0
00
4
0.0002
0.0012
-0.0024
-0.002
-0.0016
-0.0012
-0.0008
-0.0004
0.0002
0.0006
0.001
0.0014
0.0018
0.0022
MAGICS 6.9.1 hyrokkin - neh Tue Jul 25 19:19:38 2006
Mean Assimation Temperature Increment
-0.4 -0.2 0 0.2 0.4 0.6temperature
-400
-200
Dep
th (m
)
S3-a S3-cMean(199301-200201) of Model minus Observations
eqind-All in situ data
Western Pacific Equatorial Indian
Analysis minus Observations
DATA ASSIM
NO DATA ASSIM
• Equatorial Pacific heat content is model dependent
• Slope of Pacific Eq. thermocline controlled by winds
ERA40 produces weak thermocline slope in most models
• Too diffuse thermocline in Indian Ocean?
Sensitivities: preliminary results from ENACT/GSOP
MEAN STATE:
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 11
Strawman for the CNTL integration
• From spin up, launch the integrations, using daily atmospheric forcing fluxes plus some restoring terms:
3D relaxation to climatology of T and S (~10 year time scale) Strong relaxation to time-varying values of SST (~2-3 days t.s) Relaxation to climatological Surface Salinity (1 year t.s) If free surface, volume preserving constrains.
• The restoring terms are used to diagnose errors.
• Atmospheric forcing (daily values): Momentum flux: ERA40 0-24 wind stress Heat flux:
o ERA40 0-24 solar, latent and sensible heat fluxes. PLUSo Strong relaxation to daily values of SST (~2 days time scale) (Reynolds from
1982) Fresh Water flux:
o ERA40 0-24 PME + ENACT correctiono Weak Relaxation to climatological SSS (~12 month time scale)o If free surface, some volume preserving constrains.
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 12
CNTL integration at ECWMF
• Decent Inter-annual ENSO variability
50O E 100OE 150OE 160OW 110OW 60OW 10OW
Longitude
40OS
30OS
20OS
10O
S
0O
10O
N
20O
N
30O
N
40ON
Latit
ude
40OS
30OS
20OS
10O
S
0O
10O
N
20O
N
30O
N
40ON
Plot resolution is 1 in x and 1 in ySurface fieldSea level contoured every 0.1 mCorrel: Control
Interpolated in y
20020101 ( 9 year mean)
0.5 0.5
0.5
0.5
0.5
0.6
0.6
0.6
0.6
0.6
0.6
0.7
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0.80.9
0.9
-6
-5
-4
-3
-2
-10.5
0.6
0.7
0.8
0.9
0.98
MAGICS 6.9 hyrokkin - neh Thu Sep 9 12:12:36 2004
Correlation with altimeter data (1993-2003)
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 13
CNTL integration at ECWMF
• Some MOC variability
1960 1970 1980 1990 20001.0·107
1.5·107
2.0·107
2.5·107
3.0·107
0001 ATL26N 168 vmona_d.assim_an0 Trend= -0.074 +/- 0.020 Sv/y; In 10y = -4.1%0001 ATL26N 168 vmona_d.control_an0 Trend= -0.029 +/- 0.013 Sv/y; In 10y = -2.0%euj7 ATL26N 168 vmona_d.control_an0 Trend= -0.009 +/- 0.006 Sv/y; In 10y = -0.6%Brydend estimation Trend= -0.159 +/- 0.162 Sv/y; In 10y = -8.7%
CLIVAR WORKSHOP. Barcelona 4-6 June 2007: Joint Proposal to WGOMD 14
CNTL integration at ECWMF
• As initial conditions, decent forecast skill.
0 1 2 3 4 5 6 7Forecast time (months)
0.4
0.5
0.6
0.7
0.8
0.9
1
An
om
aly
co
rre
latio
n
wrt NCEP adjusted OIv2 1971-2000 climatology
NINO4 SST anomaly correlation
0 1 2 3 4 5 6 7Forecast time (months)
0
0.2
0.4
0.6
0.8
Rm
s e
rro
r (d
eg
C)
Ensemble sizes are 3 (esj6) and 3 (esj6) 76 start dates from 19870101 to 20051001
NINO4 SST rms errors
Fc esj6/m1 Fc esj6/m0 Persistence Ensemble sd
MAGICS 6.10 hyrokkin - neh Thu Sep 7 19:11:46 2006
S3 Nodata S3 Assim