Develop a Hybrid Coordinate Ocean Model with Data Assimilation Capabilities

2002 ◽  
Author(s):  
W. C. Thacker
Keyword(s):  
Data Assimilation ◽  
Ocean Model ◽  
Hybrid Coordinate Ocean Model

scholarly journals A STUDY OF THE IMPACT OF ALTIMETRY DATA ASSIMILATION ON SHORT-TERM PREDICTABILITY OF THE HYCOM OCEAN MODEL IN REGIONS OF THE TROPICAL AND SOUTH ATLANTIC OCEAN

2013 ◽  
Vol 31 (2) ◽  
pp. 271 ◽  
Author(s):  
Leonardo Nascimento Lima ◽  
Clemente Augusto Souza Tanajura
Keyword(s):  
Data Assimilation ◽  
Sea Surface Height ◽  
Ocean Model ◽  
South Atlantic ◽  
Sea Surface ◽  
Optimal Interpolation ◽  
Altimetry Data ◽  
Hybrid Coordinate Ocean Model ◽  
Along Track ◽  
The Impact

ABSTRACT. In this study, assimilation of Jason-1 and Jason-2 along-track sea level anomaly (SLA) data was conducted in a region of the tropical and South Atlantic (7◦N-36◦S, 20◦W up to the Brazilian coast) using an optimal interpolation method and the HYCOM (Hybrid Coordinate Ocean Model). Four 24 h-forecast experiments were performed daily from January 1 until March 31, 2011 considering different SLA assimilation data windows (1 day and 2 days) and different coefficients in the parameterization of the SLA covariance matrix model. The model horizontal resolution was 1/12◦ and the number of vertical layers was 21. The SLA analyses added to the mean sea surface height were projected to the subsurface with the Cooper & Haines (1996) scheme. The results showed that the experiment with 2-day window of along-track data and with specific parameterizations of the model SLA covariance error for sub-regions of the METAREA V was the most accurate. It completely reconstructed the model sea surface height and important improvements in the circulation were produced. For instance, there was a substantial improvement in the representation of the Brazil Current and North Brazil Undercurrent. However, since no assimilation of vertical profiles of temperature and salinity and of sea surface temperature was performed, the methodology employed here should be considered only as a step towards a high quality analysis for operational forecasting systems.   Keywords: data assimilation, optimal interpolation, Cooper & Haines scheme, altimetry data.   RESUMO. Neste estudo, a assimilação de dados de anomalia da altura da superfície do mar (AASM) ao longo da trilha dos satélites Jason-1 e Jason-2 foi conduzida em uma região do Atlântico tropical e Sul (7◦N-36◦S, 20◦W até a costa do Brasil) com o método de interpolação ótima e o modelo oceânico HYCOM (Hybrid Coordinate Ocean Model). Foram realizados quatro experimentos de previsão de 24 h entre 1 de janeiro e 31 de março de 2011, considerando diferentes janelas de assimilação de AASM (1 dia e 2 dias) e diferentes coeficientes na parametrização da matriz de covariância dos erros de AASM do modelo. A resolução horizontal empregada no HYCOM foi 1/12◦ para 21 camadas verticais. As correções de altura da superfície do mar devido à assimilação de AASM foram projetadas abaixo da camada de mistura através da técnica de Cooper & Haines (1996). Os resultados mostraram que o experimento com assimilação de dados ao longo da trilha dos satélites com a janela de 2 dias e com parametrizações da matriz de covariância específicas para sub-regiões da METAREA V foi o mais acurado. Ele reconstruiu completamente a altura da superfície do mar e também proporcionou melhorias na circulação oceânica reproduzida pelo modelo. Por exemplo, houve substancial melhoria da representação nos campos da Corrente do Brasil e Subcorrente Norte do Brasil. Entretanto, tendo em vista que não foi realizada a assimilação de perfis verticais de temperatura e de salinidade e da temperatura da superfície do mar, a metodologia apresentada deve ser considerada apenas como um passo na conquista de uma análise oceânica e de um sistema previsor de qualidade para fins operacionais.   Palavras-chave: assimilação de dados, interpolação ótima, técnica de Cooper & Haines, dados de altimetria.

scholarly journals OCEAN FORECASTS IN THE SOUTHWESTERN ATLANTIC: IMPACT OF DIFFERENT SOURCES OF SEA SURFACE HEIGHT IN DATA ASSIMILATION

2013 ◽  
Vol 31 (2) ◽  
pp. 243 ◽  
Author(s):  
Raquel Leite Mello ◽  
Ana Cristina Neves de Freitas ◽  
Lucimara Russo ◽  
Jean Felix de Oliveira ◽  
Clemente Augusto Souza Tanajura ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Ocean Model ◽  
Sea Surface ◽  
Naval Research ◽  
Southwest Atlantic ◽  
Argo Data ◽  
Ocean Data Assimilation ◽  
Hybrid Coordinate Ocean Model ◽  
Oceanographic Data ◽  
The One

ABSTRACT. The objective in this paper is to analyze which Sea Surface Height (SSH) source applied to HYCOM (HYbrid Coordinate Ocean Model) is best suited to numerical prediction of the Southwest Atlantic Ocean. To this end two nested grids were used. One grid for the entire Atlantic Ocean (1/4◦) nesting the grid for the Southwest Atlantic (1/12◦) in the one-way mode. Three forecast experiments with different SSH data sources (Naval Research Laboratory – NRL; Archiving, Validation and Interpolation of Oceanographic Data – AVISO and MERCATOR) applied to constrain the initial conditions and a control forecast experiment without SSH constrain were compared. The comparison of forecasted temperature and salinity profiles with Argo data showed good correlation, over 0.98 for temperature and 0.87 for salinity. The NRL experiment – with SSH obtained by HYCOM+NCODA (Navy Coupled Ocean Data Assimilation System) GLOBAL 1/12◦ analysis was the one that best represented the average temperature and salinity profile with respect to the Argo data. Keywords: HYCOM, numerical modeling, ocean prediction, Argo profiler, Taylor diagram. RESUMO. O objetivo deste trabalho é avaliar qual a fonte de dados de ASM (Altura da Superfície do Mar) imposta no modelo HYCOM (HYbrid Coordinate Ocean Model) é mais adequada para a previsão numérica do Oceano Atlântico Sudoeste. Para isto foram utilizadas duas grades aninhadas, uma grade para todo o Oceano Atlântico (1/4◦) aninhada no modo one-way a outra grade para o Atlântico Sudoeste (1/12◦). Foram realizados três experimentos com diferentes campos de ASM (Naval Research Laboratory – NRL; Archiving, Validation and Interpolation of Oceanographic data – AVISO e MERCATOR) impostos na condição inicial e um experimento controle no qual não foi usada fonte de ASM externa. A comparação dos perfis de temperatura e salinidade entre os dados observados e os resultados do modelo apresentou boa correlação, maior que 0,98 para a temperatura e 0,87 para a salinidade. O experimento NRL com ASM total obtido dos resultados do HYCOM+NCODA (Navy Coupled Ocean Data Assimilation) GLOBAL 1/12◦ foi o que melhor representou o perfil médio de temperatura e salinidade observado.  Palavras-chave: HYCOM, modelagem numérica, previsão oceânica, perfiladores Argo, diagrama de Taylor.

Evaluation of Global Ocean Data Assimilation Experiment products on South Florida nested simulations with the Hybrid Coordinate Ocean Model

2008 ◽  
Vol 59 (1) ◽  
pp. 47-66 ◽  
Author(s):  
Vassiliki H. Kourafalou ◽  
Ge Peng ◽  
HeeSook Kang ◽  
Patrick J. Hogan ◽  
Ole-Martin Smedstad ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Ocean Model ◽  
South Florida ◽  
Global Ocean ◽  
Assimilation Experiment ◽  
Ocean Data Assimilation ◽  
Hybrid Coordinate Ocean Model

scholarly journals Generalized Kalman Filter and Ensemble Optimal Interpolation, Their Comparison and Application to the Hybrid Coordinate Ocean Model

Mathematics ◽  
2021 ◽  
Vol 9 (19) ◽  
pp. 2371
Author(s):  
Konstantin Belyaev ◽  
Andrey Kuleshov ◽  
Ilya Smirnov ◽  
Clemente A. S. Tanajura
Keyword(s):  
Kalman Filter ◽  
Data Assimilation ◽  
Ocean Circulation ◽  
Ocean Model ◽  
Computational Effort ◽  
Optimal Interpolation ◽  
State Variables ◽  
Ensemble Optimal Interpolation ◽  
Hybrid Coordinate Ocean Model ◽  
Generalized Kalman Filter

In this paper, we consider a recently developed data assimilation method, the Generalized Kalman Filter (GKF), which is a generalization of the widely-used Ensemble Optimal Interpolation (EnOI) method. Both methods are applied for modeling the Atlantic Ocean circulation using the known Hybrid Coordinate Ocean Model. The along-track altimetry data taken from the Archiving, Validating and Interpolating Satellite Oceanography Data (AVISO) were used for data assimilation and other data from independent archives of observations; particularly, the temperature and salinity data from the Pilot Research Array in the Tropical Atlantic were used for independent comparison. Several numerical experiments were performed with their results discussed and analyzed. It is shown that values of the ocean state variables obtained in the calculations using the GKF method are closer to the observations in terms of standard metrics in comparison with the calculations using the standard data assimilation method EnOI. Furthermore, the GKF method requires less computational effort compared to the EnOI method.

Previsões Oceânicas no Atlântico Sudoeste (METAREA V) Utilizando

2014 ◽  
Vol 31 (2) ◽  
Author(s):  
Raquel Leite Mello ◽  
João Bosco Rodrigues Alvarenga ◽  
Ana Cristina Neves de Freitas ◽  
Clemente Tanajura ◽  
Lucimara Russo ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Research Laboratory ◽  
Ocean Model ◽  
Naval Research Laboratory ◽  
Naval Research ◽  
Ocean Data Assimilation ◽  
Hybrid Coordinate Ocean Model

Neste trabalho foi utilizado o modelo hidrodinâmico HYCOM (HYbrid Coordinate Ocean Model) em duas grades aninhadas. Uma grade para todo o Oceano Atlântico (1/4º) aninhada a outra com para a Metarea V (1/12º). O objetivo é avaliar qual a fonte de dados de ASM (Altura da Superfície do Mar) imposta no modelo é mais adequada para a previsão numérica da área de interesse. Foram realizados três experimentos com diferentes campos de ASM impostos na condição inicial com o esquema de Cooper & Haines (1996) e um experimento controle no qual não foi imposta fonte de ASM externa. De maneira geral, os resultados obtidos através das simulações do HYCOM apresentam-se satisfatórios quando comparados aos dados observacionais de temperatura e salinidade de derivadores Argo. O experimento NRL com ASM total obtido dos resultados do HYCOM+NCODA (Navy Coupled Ocean Data Assimilation) GLOBAL 1/12º obtidos no NRL (Naval Research Laboratory) foi o que melhor representou o perfil médio de temperatura e salinidade observado. No Diagrama de Taylor, este mesmo experimento mostrou maior correlação (0,99), menor erro quadrático médio (0,99ºC) e desvio padrão (8,76ºC) muito próximo dos dados observados (8,67ºC).

scholarly journals Argo data assimilation into HYCOM with an EnOI method in the Atlantic Ocean

Ocean Science ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 195-213 ◽  
Author(s):  
D. Mignac ◽  
C. A. S. Tanajura ◽  
A. N. Santana ◽  
L. N. Lima ◽  
J. Xie
Keyword(s):  
Data Assimilation ◽  
Atlantic Ocean ◽  
Heat Content ◽  
Ocean Model ◽  
Optimal Interpolation ◽  
Argo Data ◽  
Thermohaline Structure ◽  
Vertical Coordinate ◽  
Ocean Data Assimilation ◽  
Hybrid Coordinate Ocean Model

Abstract. An ocean data assimilation system to assimilate Argo temperature (T) and salinity (S) profiles into the HYbrid Coordinate Ocean Model (HYCOM) was constructed, implemented and evaluated for the first time in the Atlantic Ocean (78° S to 50° N and 98° W to 20° E). The system is based on the ensemble optimal interpolation (EnOI) algorithm proposed by Xie and Zhu (2010), especially made to deal with the hybrid nature of the HYCOM vertical coordinate system with multiple steps. The Argo T–S profiles were projected to the model vertical space to create pseudo-observed layer thicknesses (Δ pobs), which correspond to the model target densities. The first step was to assimilate Δ pobs considering the sub-state vector composed by the model layer thickness (Δ p) and the baroclinic velocity components. After that, T and S were assimilated separately. Finally, T was diagnosed below the mixed layer to preserve the density of the model isopycnal layers. Five experiments were performed from 1 January 2010 to 31 December 2012: a control run without assimilation, and four assimilation runs considering the different vertical localizations of T, S and Δ p. The assimilation experiments were able to significantly improve the thermohaline structure produced by the control run. They reduced the root mean square deviation (RMSD) of T and S calculated with respect to Argo independent data in 34 and 44%, respectively, in comparison to the control run. In some regions, such as the western North Atlantic, substantial corrections in the 20 °C isotherm depth and the upper ocean heat content towards climatological states were achieved. The runs with a vertical localization of Δ p showed positive impacts in the correction of the thermohaline structure and reduced the RMSD of T (S) from 0.993 °C (0.149 psu) to 0.905 °C (0.138 psu) for the whole domain with respect to the other assimilation runs.

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