1. introduction 2. goals 3. methodology 4. results 5. other results 6. conclusions
DESCRIPTION
GODAE OceanView / CLIVAR GSOP Technical Workshop on Observing System Evaluation and Inter-comparisons, 13-17 June 2011, UCSC A Sensitivity Study of Short-Range Forecasts over the Atlantic METAREA V with HYCOM and the Cooper and Haines Scheme Using Different Sea Surface Heights - PowerPoint PPT PresentationTRANSCRIPT
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GODAE OceanView / CLIVAR GSOP Technical Workshop on Observing System Evaluation and Inter-comparisons, 13-17 June 2011, UCSC
A Sensitivity Study of Short-Range Forecasts over the Atlantic METAREA V with HYCOM and the Cooper and Haines Scheme Using
Different Sea Surface Heights
Jean Oliveira1, João Alvarenga1, Raquel Mello1, Ana Freitas1, Lucimara Russo1 , Clemente Tanajura2
1 Brazilian Navy Center of Hydrography (CHM), Brazil2Institute of Physics, Federal University of Bahia (UFBA), Brazil
Oceanographic Modeling and Observation Network (REMO)www.rederemo.org
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1. Introduction
2. Goals
3. Methodology
4. Results
5. Other Results
6. Conclusions
Outline
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• REMO is a research group in physical oceanography and operational oceanography established in January 2008
• The members are researchers and students from four Brazilian universities, the Brazilian Navy and the PETROBRAS research center CENPES
1. Introduction
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1. Introduction (cont.)
- Pre-operational short-range ocean forecasts with HYCOM (7 days) and ROMS (3 days) using NCEP GFS forcing since Oct ober 2009
- Operational forecasts with HYCOM in the Brazilian Navy CHM with the Cooper & Haines scheme (1996) (C&H) since February 2010
HYCOM 1/4o 21L HYCOM 1/12o 21L ROMS 5-13 km 32L
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2. Goals - Evaluate HYCOM 1/12o Forecasts
- Investigate the behavior of the model predictability along time
- Investigate the model sensitivity to different initial conditions
- Develop routines to validate model simulations and forecasts according to GODAE OceanView standards
3. Methodology - Construct initial condition with u, v, T and S from the HYCOM+NCODA
system on 00Z 1 Feb 2010 available in z-coordinates at www.hycom.org
- 7-day forecasts from 1 Feb 2010 until 31 Mar 2010 using GFS forcing
- HYCOM 1/4o : initial condition from C&H with the 24 h forecast as background and SSH from HYCOM+NCODA
- HYCOM 1/12o nested in the HYCOM 1/4o : initial condition from C&H with the 24 h forecast as background and SSH from
HYCOM+NCODA (NRL), Mercator-océan (MERCATOR) and SSH analysis (ALONG_TRACK)
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3. Methodology (cont.)
- SSH analyses were performed daily with (filtered) along-track SSH anomalies (SSHA) from Jason-1 and Jason-2 obtained from AVISO.
- OI was employed to assimilate SSHA according to Ezer & Mellor (1997)
- The background SSHA was obtained from
- The analysis was calculated from
SSHSSHSSHA bb model mean
RH(HBBH=K ' 1)
222 /exp),( LrjiB iji
)SSHAHK(Y+SSHA=SSHA bba )(
R is diagonal with constant values equal to (0.02 m)2
L = 170 km
is the SSHA model variance at point i
is the distance between point s i and j222 )()( jijiij yyxxr
2i
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3. Methodology (cont.)
- 747 Argo profilers with T-S were used to evaluate the forecasts
- Only the 24 h forecasts were investigated
- Temperature and salinity from Argo and model were interpolated to the standard Levitus vertical levels
Argo profilers1 Feb - 31 Mar 2010
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4. Results
- NRL = C&H with HYCOM+NCODA
- ALONG_TRACK = C&H with SSHA analysis
- MERCATOR = C&H with Mercator-Océan 1/4º SSH
Control
Argo
Mean Temperature Profile Mean Salinity Profile
Experiments
Control
Argo
Experiments
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- Standard deviations (Std) of the difference between the forescast and ARGO data for temperature and salinity were calculated
- Smallest values were obtained for the NRL followed by the CONTROL , ALONG_TRACK and MERCATOR experiments
4. Results (cont.)
Mean Temperature and Std (ΔT) Mean Salinity and Std (ΔS)0.2oC < Std (ΔT) < 2.4oC 0.2oC < Std (ΔT) < 2.4oC
Argo
Argo
NRL (dashed)
NRL (dashed)
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4. Results (cont.)
0 – 2000 m
0 – 100 m 125 – 800 m
Taylor Diagrams for Temperature
A – ARGOB – NRL C – ALONG_TRACKD – MERCATORE – CONTROL
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4. Results (cont.)
0 – 2000 m
0 – 100 m 125 – 800 m
Taylor Diagrams for Temperature
A – ARGOB – NRL C – ALONG_TRACKD – MERCATORE – CONTROL
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4. Results (cont.)
0 – 2000 m
125 – 800 m0 – 100 m
Taylor Diagrams for Salinity
A – ARGOB – NRL C – ALONG_TRACKD – MERCATORE – CONTROL
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16/09/10
5. Other results
- Initial condition: “interpolated” HYCOM+NCODA fields available in z-coordinate in www.hycom.org on 00Z 1 Jan 2011
- 7-day (168 h) Forecasts performed daily with Cooper and Haines, SSH from HYCOM+NCODA
- NCEP GFS forcing
Forecast minus PIRATA (8oS. 30oW) Forecast minus PIRATA (19oS. 34oW)
20 m 20 m300 m
300 m
100 m
100 m
Solid lines = 24 h forecastDashed lines = 168 h forecast
Tem
p.
Dif
fere
nce
(o
C)
Tem
p.
Dif
fere
nce
(o
C)
Leonardo Lima; Luiz Gavaza
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16/09/10
5. Other results (cont.)
- Background: “interpolated” HYCOM+NCODA fields available in z-coordinate in www.hycom.org on 00Z 1 Jan 2011
- Bergthorsson and Doos analysis with 19 profiles of T and S from Argo T and S data from surface to 2000 m performed in the Levitus z-levels;
- Application of Cooper and Haines with SSH from HYCOM+NCODA
Davi Mingac; Luiz Gavaza
BackgroundBackground
Analysis+C&H
Analysis
RMSE for Temperature (oC) RMSE for Salinity (PSU)
Dep
th (
m)
Analysis+C&H
Analysis
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16/09/10
6. Conclusions- The system HYCOM 1/12o – initialized with “interpolated”
HYCOM+NCODA fields on 1 Feb 2010 – restrained daily by Cooper and Haines with HYCOM+NCODA SSH produces good agreement with Argo data;
- When assimilation of AVISO along-track SSHA data was employed, similar (worse) results were obtained;
- The use of SSH from Mercator-Océan produced similar results to the control run without Cooper and Haines;
- In another forecast experiment (from 1 Jan 2011 to 31 Mar 2011) the 24h forecasts for T with respect to PIRATA buoys close to Brazil were very similar to the 168h forecasts
- The analysis of vertical profiles of T and S from Argo performed in z-coordinates were substantially modified by Cooper and Haines;
- An OI scheme to assimilate synthetic T(z) and ρ(z) is under evaluation and a multivariate OI system is being pursued to jointly assimilate SSHA, SST, T(z) and layer thickness.
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Thanks!