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On the Development of a Numerical Ocean Prediction for the Tropical and South Atlantic Based on HYCOM
Clemente A. S. Tanajura, Renato Ramos da Silva, Jonatas Einsiedler, Giovanni Ruggiero, Konstantin Belyaev, Jean F. de Oliveira, Edmo Campos, Afonso Paiva, Mariela Gabioux , Charles N. de Santana
Federal University of Bahia
(Abstract received 05/10/2009 for session X)
ABSTRACT
A numerical ocean forecast system for the equatorial and the South Atlantic Ocean is under development today in Brazil. The system will have HYCOM to forecast Atlantic basin-scale circulation, and ROMS and POM to forecast regional meso-scale circulation close to the Brazilian shore. The present work will focus on the developments related to HYCOM version 2.1. The pre-operational activities were initiated on September 1, 2008 with a daily 7-day forecast for the Atlantic Ocean over the domain 63oS-50oN, 70oW-20oE partitioned by a 1/3o horizontal resolution grid with 22 vertical hybrid layers. The model was forced by the NCEP GFS 1o resolution 6 hr atmospheric forecasts without ocean data assimilation. On January 1, 2009 a 1/12o grid over 45oS-5oS, 50oW-20oW was nested in the 1/3o grid operationally with the same atmospheric forcing. The Mellor and Ezer assimilation scheme was used in the 1/12o grid to assimilate synthetic data of vertical profiles of potential temperature and potential density in z-coordinate. An interpolation scheme from the isopycnal- to the z-coordinate –that uses a Lagrange multiplier to impose the conservation of the mean horizontal current in each layer– guarantees minimal errors in the transformation. In June 2009, the system will be upgraded to the HYCOM 2.2.16 and will include new runs with the Cooper and Haines scheme to correct altimetry. A data assimilation system based on as Extended Kalman Filter method is also being investigated to assimilate temperature and salinity from ARGO, PIRATA, CDT and others. Also, new atmospheric forcing and assimilation of altimetry and sea surface temperature are planned to be tested in a near future. The results of the assimilation and forecast experiments were compared with observational data and with analysis from HYCOM+NCODA and MERCATOR. The prognostics that the system will produce reliable short-term forecasts in 2010 are quite positive. The system will be operational in the Brazilian Navy as the result of the Oceanographic Modeling and Observation Research Network (REMO) sponsored by PETROBRAS.
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2009 LOM Workshop, Miami, Florida Jume 1 - 3, 2009